Use of Models for Water Resources

Management, Planning, and Policy

August 1982

NTIS order #PB83-103655
Library of Congress Catalog Card Number 82-600556

For sale by the Superintendent of Documents,

U.S. Government Printing Office, Washington, D.C. 20402
Foreword .

9

‘Director

iii
Contributors to This Report

David Allee

Cornell University

Mary Anderson

University of Wisconsin, Madison

Neil Armstrong

University of Texas at Austin

John Bredehoeft

U.S. Geological Survey

James Chalmers

Mountain West Research, Inc.

Jared Cohon

Johns Hopkins University

Charles Faust

GeoTrans, Inc.

A. J. Frederick

Private consultant

James Geraghty

Geraghty & Miller

Warren Hall

Colorado State University

James Heany

University of Florida

Wayne Huber

University of Florida

Richard Hyde

Holcomb Research Institute

L. Douglas James

Utah State University

William Johnson

U.S. Army Corps of Engineers

William Lane

Bureau of Reclamation

Arun Malik

Johns Hopkins University

James Mercer

GeoTrans, Inc.

Ronald North

University of Georgia

Donald O’Connor

Manhattan College

John Peters

U.S. Army Corps of Engineers

Charles ReVelle

John Hopkins University

Richard Ribbens

Bureau of Reclamation

Donald Robey

U.S. Army Corps of Engineers

Leonard Shabman

Virginia Polytechnic Institute

Daniel Sheer

Interstate Commission on the Potomac River Basin

Soroosh Sorooshian

Case Western Reserve University

Clair Stalnaker

U.S. Fish and Wildlife Service

Roland Steiner

Johns Hopkins University

James Thomas

Bureau of Reclamation

Harry Torno

U.S. Environmental Protection Agency

Richard Tucker

Dames & Moore

Andrew Waldo

National Counsel Associates, Inc.

Porter Ward

U.S. Geological Survey

Walter Wunderlich

Tennessee Valley Authority

Jeffrey Wright

Johns Hopkins University

OTA appreciates the assistance of many additional people who contributed to this report:

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Participants in the two OTA water resource modeling workshops.

Federal agency personnel who responded to the OTA Federal agency survey.

State agency personnel who responded to the OTA State agency survey, and directors of the State water resources

research institutes who suggested appropriate respondents.

The professional societies that reviewed technical materials, including the American Geophysical Union, the

American Society of Civil Engineers, the American Water Resources Association, and the National Water

Well Association.
OTA Water Resource Models Assessment Staff

John Andelin, Assistant Director, (ITA

Science, Information, and Natural Resources Division

Robert W, Niblock, Oceans and Environment Program Manager

Project Staff

Robert M. Friedman, Project Director

Chris Ansell, Research Assistant

Stuart Diamond, * Writer/Editor

Nancy Ikeda, Policy Analyst

Yacov Y. Haimes, Consultant

Administrative Staff

Kathleen A. Beil Linda G. Wade Jacquelynne R. Mulder

OTA Publishing Staff

John C. Holmes, Publishing Officer

John Bergling Kathie S. Boss Debra M. Datcher Joe Henson

● OTA contract personnel
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-. Contents

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Chapter

1.

2.

3.

4.

5.

6.

A.

B.

c.

D.

E.

Summary, Issues, and Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Introduction to Water Resource Models . . . . . . . . . . . . . . . . . . . . . . .

General Issues in Model Development, Use, and Dissemination . .

Federal Use and Support of Water Resource Models

Use of Models by State Governments . . . . . . . . . . . . . /

Modeling and Water Resource Issues . . . . . . . . . . . . .

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Sumpary of Model Use by Individual Federal Agencies, . . . . . . . .

Summaries of Related Modeling Studies . . . . . . . . . . . . . . .’. . . . . . . .

Additional References to Models and Model~g Sm% ~”” “ “”” ● o

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Appendix

Summary of Findings from OTA Workshops on Water Resource Modem

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Tables of Responses to OTA Survey of State-Level~Model Use. . . . . . . . . . . .

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Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ● . “ . * .

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Chapter 1

Summary, Issues, and Options
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Scope . . . . . . . . . . . . . . ....4.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Introduction . ............-...:., . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -

Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . “

Issue 1. Improving Federal Problem-Solv

Issue 2. Meeting the N’eeds of the States

ng Capabilities , . . . . . . . . . . . . . . . . . .

..,., . . . . . . . . . . . . . . . . . . . . . . . . ..,,

Issue 3. Establishing Appropriate Modeling Strategies Within Individual

Federal Agencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Issue 4. Providi

Issue 5, Federal

n,g Potential Users With Information About Existing Models .

Support for Model-Related Training . . . . . . . . . . . . . . . . . . .

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Chapter 1

Summary, Issues, and Options

SCOPE ‘. . .’

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This assessment is intended as a guide for Con- .The full report includes: ., J.. , .

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4 ● Use of Mode/s for Water Resources Management, Planning, and Policy

INTRODUCTION

Between 1950 and 1975, the Federal Government spent over $45 billion to develop, maintain,

and improve the Nation’s water resources; 1 expenditures have spiralled to even higher levels over the

past decade. Federal efforts range from constructing dams to increase the reliability of water supplies, generate hydroelectric power, improve flood

control, and provide recreational opportunities; to

studies for determining whether flood plain areas

are sufficiently safe to permit building activities;

to providing wastewater treatment for reducing

health and environmental risks due to polluted

rivers, streams, and lakes.

Decisions affecting water resources are made by

the Federal, State, and local governments, and by

the private sector. These decisions include designing day-to-day management procedures for operating facilities most efficiently, as well as planning

and implementing long-range policies for water resources management and construction. Decisions

of the latter kind involve large sums of money, and

may affect the availability and quality of water for

many decades to come. As the Nation grows, and

excess water resource capacities diminish, it

becomes increasingly important to manage existing

facilities, improve the efficiency of water use, and

make long-range plans in ways that maximize the

return on natural, capital, and human resources.

Mathematical models are among the most sophisticated tools available for analyzing water

resource issues. They can use the capabilities of

today’s digital computers to perform and integrate

millions of calculations within seconds, in order to

understand and project the consequences of alternative management, planning, or policy-level activities. Models only assist in decisionmaking—they

provide information that people must interpret in

light of existing laws, political and institutional

structures, and informed professional and scientific

judgment. Nonetheless, models can significantly

improve the informational background on which

decisions are based, and substantially reduce the

‘Viessman, et al., 7%e Nation Water Outlook to the Year 2000. The

$45 billion estimate includes expenditures by the Army Corps of

Engineers, the Bureau of Reclamation, the Soil Conservation Service, the Tennessee Valley Authority, and the Environmental Protection Agency’s Construction Grants Program outlays.

cost of managing water resources. Although the

Federal Government spends approximately $50

million on water-related mathematical models annually, such tools are instrumental in planning

billions of dollars of annual water resource inPhoto credit: Environmental Protection Agency

Photo credit: U.S. Depaflment of Agriculture

Federal, State, and local governments, and the private

sector, provide billions of dollars to support the

construction of dams, reservoirs, and water treatment

facilities. Mathematical models are becoming

increasingly important in determining the need for such

facilities, and in planning, designing, and operating them.

Models can be used to help operate existing structures

such as the McNary Dam on the Columbia River (top),

as well as to develop and run new facilities like the

illustrated water purification system in

Duncan, Okla. (bottom)
Ch. 7—Summary, Issues, and Options . 5

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vestments, and managing hundreds of billions of

dollars of existing facilities.

The role of models in managing water resources

has grown dramatically over the past decade—a

period in which water resource management itself

has become increasingly important. High rates of

economic and population growth in water-short

areas of the country, decreased availability of water

from major ground water aquifers, and increased

public concern for the quality of its drinking water,

lakes, and rivers have made it even more necessary

to manage water resources carefully. In addition,

the issue of who is to manage water resources has

gained prominence in the political arena, as ways

are sought to increase States’ responsibilities for

assuring adequate and safe water supplies.

The magnitude of the national investment in

water resources calls for systematic use of the best

analytic tools available to manage this investment.

Over the past 20 years, models and sophisticated

data processing systems have been advanced as

promising great improvements in water resources

management, planning, and policy. Yet many consider that these tools have not yet lived up to earlier

expectations. OTA was requested to study the use

of models in freshwater resources analysis in order

to determine their current capabilities, identify appropriate roles for their use, and suggest options

for improving modeling efforts and model use.

Photo credits; :’ Ted Spiege/, 1982

Pipelines to provide new supplies of water for the State

of Arizona (top) and the New York City water tunnel (bottom) demonstrate the magnitude of the Nation’s water

resource needs. Reliable forecasts of an area’s water requirements are critical for designing efficient and adequate water transport and distribution systems. Models

can be used to estimate future demands for water, and

to assist in water system design

FINDINGS

Mathematical models have significantly expanded the Nation’s ability to understand and

manage its water resources. They are currently

used to investigate virtually every type of water resource problem; for small- and large-scale studies

and projects; and at all levels of decisionmaking.

In some cases, models have increased the accuracy of estimates of future events to a level far

beyond “best judgment” decisions. In other areas,

they have made possible analyses that could not

be performed empirically or without computer

assistance. Further, models have made it feasible

to quantitatively compare the likely effects of alternative resource decisions. A few examples of situations in which models have been applied will illustrate their uses:

● Water in excess of amounts needed by crops

is often applied to fields to leach out accumulated salts. This results in high water use
/

e ● use of MOOE;S tor Water Resowces Management, Planning, and Pollcy

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e

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and high salt loadings in irr”iga&o~~ flows

returned [(} streams. New hlexico scientists developed ii , ,[)mP

 uter r~l<j, ~:‘ ? to estimwe the

minimum a)~lount of lea~ iilng water ~cquired

to maint~in crop yields and favorable soil

salinities. The model has resulted in annual

savings in lifter costs of $.’l~0,000 for the Pecos

River bas ;~ in New MexiLJ. In addition, the

lower irri~i~[ion return flows have reduced the

salt input i(~ the Pecos I? ~’.wr by 235,000 tons

per year.

The Clear~ Water Act curi(:ntly requires’~clis~

chargers to Aneet effluent---or ‘end-of-pipe’ ‘—

standards. and, in addition, to discharge no

more of iJ. ) ‘(~llutant tha~-, w~eiving waters+?n

safely C(if : v ~ according u; a fixed receivl~g

water qui~ilt~ standard. Models are an @@@

tive means of projecting :1 (e rec~”ivimg W@’

quality lhc.t results from different leveh. bf

discharge. and are thus ;~ major aid in deter+

mining WIIA[ levels of discharge are peivnissible unchr ~ ~’eiving vat(’, :~andar~l’

For the l~~)~thern Virginia area, 197/ ;vas the

driest year since 1950. The Occoquan Reservoir servinv northern Virqinia was nearly

empty, ai-i; ! daily withdr:i’”, JS exc~>~:~t:d daily

inflows. I_rsing its extended streamflow prediction moclel, the National Weather Service

(NWS) determined that there was a lo-percent

risk of reaching emergency reservoir knds-a

risk deerr~; ~ I unacceptable by local authorities.

The model was then used to project that an

acceptable 2- to 3-pereent risk of reaching

emergency reservoir le~-els would require reducing J$ ithdrawals by about 20 percent.3 4

Reserv(~i~s are usual]> multiple-purpose facilities, m,. ~ i Y“ UJ whose [J!) it’~t i ~~? ‘I . conk[ or co~npete. Rcstrvoir mana~ers need to retain sufficient wtit(’r to ensure an adequate future supply for users, yet must release enough for flood

control ~Ur~(JSes, M \\’Cll ZM t(-) ensure ZKkqUate

low-flow levels to protect aquatic life and minimize the cost of pollution control downstream.

‘Impacts of the L’ni~(rsi~ Water Resear~h Program, Task ~’or~c on Research and Education in Water Resources, U.S. Department of the

Interior, March 1981, p. 9.

3D. C. Curtis andJ. C. Schaake, Jr., ‘‘The Nationat Weather Service Extended Sttiamflow Technique. ” Conference on Reservoir Systeni Regulation, ASCE, Boulder, ~do., ~{lg. 14-17. 1979.

41). P. Sheer, “Analyzing the Risk of Drought: The Occoquan Experience,’’Journa/ of the A&an Water J4’orks Association, May 1980.

Additional objectives include maximizing hydropower production (by releasing water) and

recreational opportunities (retaining water for

reservoir lake users, and releasing water for

stream and downstream lakti users). Mathematical models’,have been used on many of the

Natipn’s major river systems to address confi”~ ti~e demands by suggesting optimal

arn~nf~’ and timing of reservoir releases.

,~: ~~‘~@@@y investigators developed a

‘ ~-opt;fitititionmcthdtodesi~asewer :.

~=#!&if~r ~hb Long Island Regional Plan-

‘ ~ @tn=~%a~di.: The resulting analysis indicated

!‘ th~~~~~+wer tietiyork that would meet commu-

‘“&&&@s edut~-be built and operated for $40

z rniIIi& @ss’&@;cc@f a design developed by

~ ~~~~~ug~~vcti.~on~ ~n~ytic~ ~ethods. s

Mu&i. have the potential to provid&@# ,

greater benefits for water resource decisionmaking in the future. As models are refined and

receive wider acceptance, they will be able to increase the efficiency of water resource management ~eacourage cost-effective decisionmaking. Such rnodeis can do much to increase the raL imm.lity of regulations and [he standard-setting

process, and can generally provide a sound scientific basis fa water policy. The following examples

illustrate ~g, potential benefits of’ f’uture expansion

i~~ m~~&@~: ~ ‘

-=+ ~ :3 ;: : .

● &.49k ad 1975, the Tennessee Valley

Au@~, (TVA) spent over $2 billion for

~!&&~tir:es development and manage-

=~~~ovmg rainfall forecasting and reswp

Vt&$t?kxh.tling can make a very significazit

contribution to the benefits that accrue from

these water development projects. Recent

szmpacts of t~ university Water Research Progam, OP. cit., P. 4.
Ch. l-Summ6vy, Issues, and Options ● 7

I

I stuches on six TVA reservoirs found the potential for a 20-percent improvement in operations and annual savings of $4 million through

~\]{: ;mplenlcntation of a s~stcm of reser~roi’r

scheduling models. G

.NWS estimated that tht~ installation of a

~?fi~,ooo” ?n{}deling systenl m forecast floods

on !Ike Connectictlt River basin would provide

a reduction in flood damages exceeding $1.5

million per year.7

Nfcdels assist farmers in scheduling irrigz.ticm.s

to optimize water conservation while md-intaining crop productivity. In INebraska, improved

irrigation scheduling has resulted in 25- to

35-percent savings in water pumped #nd cfwy-

~>’ (. CJsts pCX” year. 8

;1 ,, t; ,i,

Water resource models vary greatly i~&&

capab~ !ities and limitations arid must be ciirehd+

ly selected and used by knowledgeable pro&- ‘

sionals, Some models are designed for managei]~t:iit ~~ithin small watersheds; others are uked in

> ~ 7 fl n i ‘ ‘, for la C[W ge~-~~raphic:ll areas. Some are

;if~sigyle~ I [o prm’icie highly accurate rN.@ufic? ~~+

tin-mtes; others will provide only gene@ appt-@cimations. some models are designed for dtuat~ohs

i~ J whit. ~: data arc scarce: other r~mdels require large

amounts of data. h some instances, decisionrna.kers

need only “ballpark” accurac)’ to make decisions,

hll! in Orher instances mo(iel accuracy may be extrcmcly important. A clecisionmaker may rccjuire

:1 differc~nt mod{’] in each case, even tlmugh similiar

kinds of problems are being analyz~d~

Since modeling is a rapidly advancing and highly

specialized field. it is extremely diffi~~:for decisionmakers and managers to stay abre~t of new

developments, or ev(’n to fully unc$’&tan(l i he

capabilities and limitations of the toolh’ they currently employ. Under suc~- circu~start~es; ‘a;c~r?

tain amount of model misuse and rqis~~ust is; virtllally inevitable. A manager who t~~~. a, gi~~n

~node] to analyz( a si? uation it was n~~, tlf:d~:~ed

to address; or who overrelies on” the accuracy”of

———

“’~”. Xl. Wunderlich, ‘‘Plannwl Enhanremerit of Mratcr hlanage- ~••

rnent Methods for the TVA Reservoir System, paper pxesermd at

the National Workshop on Reservoir Systems Operation, Amerkan

Society for Civil Engineers, Aug. 13-17, 1979.

‘H. J. Day and K. K. Lee, ‘

(

Flood Damage Reduction Potential

~)! R i~w’r Forecast Servicrs in the Connecticut River Basin, .\lf~ ~ ~

‘J’echnical Memorandum NWS HYDRO-28, February 197

81mpuct~ of the Uniwmlty Water Rc~earch Program, op. cir. , p. . .

- credit: C Ted Spiegel, ?982

Agriculture account$ for ovw 80 percent of U.S. water

use. Critical shortages of water for irrigation in many

areas of the country make models for w Iudulir’j

irrigation a valuable tool for stretching lhY$fed and

increasingly expensive supplies. Th6$&~odels

determine when plants requip water, and how.,@#fr.they

will need; same can estimate reductions !rt c~-$ yields

if ifrlgatfcm is delayed or reduced ~ ‘

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often the method of choice to meet the requirements of ledslation. Many current laws regarding

+, aler resources require antiyucai work normtuly

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8 ● Use of Models for Water Resources Management, Planning, and Policy

legislation associated with model use at Federal,

State, or local levels includes:

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Clean Water Act (Public Law 95-217)

—sections 107, 201, 208, 209, 301, 302, 303,

307, 311, 314, 316, 404, and 405;

Safe Drinking Water Act (Public Law 93-523)

—sections 1412, 1421, 1422, 1424, 1443, and

1444;

Toxic Substances Control Act (Public Law 94-

469)—sections 4, 5, and 6;

Resource Conservation and Recovery Act

(Public Law 94-580)–sections 1008 and 8006;

Endangered Species Act (Public Law 93-205)

—section 7;

Surface Mining Control and Reclamation Act

(Public Law 95-87)–sections 506, 510, and

515;

Soil and Water Resource Conservation Act

(Public Law 95-192)–sections 5 and 6;

Water Resources Planning Act (Public Law

89-80)—section 102;

Coastal Zone Management Act (Public Law

94-370)—section 305;

Executive Order No. 11988 (Floodplain Management);

Flood Control Act of 1936 and Amendments—

sections 1, 2, and 3;

National Flood Insurance Act of 1968—section

73;

Water Research and Development Act (Public

Law 95-467)—section 1360;

Federal Reclamation Act of 1902 and Amendments—43 U.S.C. 421 and 422;

National Environmental Policy Act (Public

Law 91-190)—sections 102 and 103; and

Atomic Energy Act of 1954—10 CFR 20, 50,

61.

In translating legislative requirements into

management practices, agencies often recommend procedures that depend on the use of

models. The Clean Water Act, for instance, requires States to determine the “total maximum

daily loads” for those sources of pollutants that cannot meet water quality standards through effluent

limitations regulations. This requires States to

predict the water quality resulting from a number

of point-source loadings—a responsibility that implicitly requires the use of ‘wasteload allocation’

models. EPA’s Waste Load Allocation Guidance

Memorandum (Sept. 5, 1979) strongly encourages

the use of models for performing wasteload allocations. The memo reads:

The link between wasteload allocations and

stream standards is a mathematical model to predict water quality as a function of waste discharges.

Such models exist and are integral parts of the

methodology. 9

9’ ‘Funding of W’astc Load Allocations and Water Quality Anatyses

for POTW Decisions, Construction Grants Program Requirements

Memorandum, U.S. Environmental Protection Agcnc), PRNI No.

79-11, Sept. 5, 1979, “Preliminar) Technical Guidance for W’LA

Studies, ” p. 4

Photo credit: r Ted Spiegel, 1982

Models are important tools for determining whether

individual point-sources of water pollution will prevent

rivers, lakes, and streams from meeting Federal water

quality standards. Using models, planners can determine

what levels of discharge would be acceptable before

treatment facilities are insta//ed; such information is

extremely valuable for designing effective

treatment strategies
Ch. l—Summary, Issues, and Options ● 9

Developing and using models is a complex

undertaking, requiring personnel with highly

developed technical capabilities, as well as adequate budgetary support for computer facilities,

collecting and processing data, and numerous

additional support services. Such capabilities

presently reside primarily within the Federal

Government, or are secured from the private sector with Federal funding. For fiscal year 1979,

direct and indirect Federal expenditures in support of model development, dissemination, and

use for water resources are estimated at $40

million to $50 million annually. The Army Corps

of Engineers, the U.S. Geological Survey (USGS),

and the Environmental Protection Agency (EPA)

are the principal agencies involved in water resource

modeling activities, and together they account for

approximately 70 percent of the funds spent in support of water modeling at the Federal level. These

expenditures represent an ongoing investment

in information that supports and improves expenditures of billions of dollars annually for

water resource development and management.

Federal training and assistance is also important

in assuring the continuing availability of hydrologists, engineers, and modelers with expertise in

water resource issues. The demand for well-trained

water resource professionals at Federal, State, and

local government levels, as well as in the private

sector, far exceeds the number of individuals who

graduate annually with relevant skills from American colleges and universities. Federal support for

university-level research and training, through the

University Water Research Program of the Department of the Interior, amounted to about $11 million

in fiscal year 1980. In addition, a number of Federal

agencies offer important training opportunities in

water resources analysis and modeling for Federal

and non- Federal employees alike. While such training is often critical for keeping professional employees abreast of developments in these fields, current

levels of instruction are clearly insufficient to meet

the growing needs of Federal, State, and local personnel.

Virtually all Federal modeling activities are

currently managed on an agency-by-agency basis. Little coordination of model development,

dissemination, or use occurs among Federal

agencies, and effective joint modeling efforts are

rare. Agencies generally have little information

about models available through or being developed

by other agencies; consequently, agencies tend to

develop new models before taking advantage of previous or ongoing modeling efforts of other agencies. While independent agency-level development

may produce tools that are more responsive to specific agency needs, the lack of cooperative development has often resulted in agencies being unable

to muster the resources to adequately develop and

support needed models. Testing models is a difficult, expensive process and very often a major barrier in the way of model use. OTA found instances

in which more than one agency had developed similar models, none of which were used for lack of

adequate testing and validation.

Most Federal agencies have no overall strategy

for the development and use of models; consequently many legislative requirements and decisionmaker needs for information are not being

met. Due to the newness and technical complexity of the modeling field, levels of communication

between decisionmakers and modelers are low,

and little coordination of model development,

dissemination, or use occurs within individual

Federal agencies. Developers, working either as

Federal employees or as private contractors, tend

to have a relatively free hand in creating and using

models. While the independence afforded to their

development has facilitated rapid advances in

design, the lack of accountability has resulted in

models that often fail to address decisionmakers’

needs for information, require impractical

amounts of data, or are not well enough explained to enable others to use them.

Successful modeling requires adequate resources for support services, such as user assistance, as well as for development. Presently,

model development has outstripped corresponding support for models. In the past, model developers have put a premium on developing models,

while support for models—documentation, validation, dissemination, user assistance, and maintenance—has been neglected. Often, resources are

focused on development, but are unavailable for

support activities. The neglect of model support has

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10 Use of Mode/s for water Resources Management, p/annjng, and po/icy

led to a multiplicity of models, most of which are

underutilized. Many of these models cannot be used

by personnel other than the developer, due to lack

of documentation, access to the model, and user

assistance.

Federal agencies that have had considerable success with modeling have devoted substantial attention to the problem-solving needs of potential users

and decisionmakers, and to providing adequate

support services. These programs generally include

a central responsibility for disseminating software

and documentation, providing training and technical assistance, and updating and maintaining

models.

State governments frequently use water

resource models, although many wish to use

them more extensively than is currently possible. OTA’S survey of State water resources professionals indicates that potential levels of model

use at the State level are at least twice as high

as current use levels. Technical capabilities at the

 State level tend to be limited—stalls are small, and

prevailing salary scales prevent many States from

hiring and/or retaining adequate numbers of personnel with modeling skills. Consequently, most

States depend primarily on the Federal Government to provide them with suitable models,

technical expertise, and training in model use.

Those Federal agencies that have had considerable

success in.assisting States have made substantial

commitments to providing support services—

USGS runs a cooperative program that currently

assists over @Xl&ate and local agencies in developing and applying models, while the Corps of Engineer sc Engineering Center (HEC )

widely provides services to State and local governments, an@- them in using HEC-built models.

Lack of @#&nation is a major barrier to State

and bed’@% models~personnel are often unaware that models for a given type of analysis

already exist. Additionally, many federally developed models are inappropriate for use at the State

level. The specific needs of States are infrequently

&

co&de@@@’ ?&k+ rn@el devdopment. Many

d

S-8$:;.% :=:= =,;

~t~th~ir ‘analytic and modeling

c+a ‘ : I@%@%l .+-=”< l!i+ e.xpandcd if ,S(ates arf m

a;sume ,a: - &’&l%d& iti-futllre tiatm resource &cj- .~g:.,

; :

,,

The issues discussed in this section focus on the

potential to improve the Federal role in developing, using, and disseminating water resource models. opportunities for increasing the efficiency and

effectiveness of current model-related efforts and

programs are noted, although the general nature

of the options set forth prohibit development of’

specific cost estimates or estimates of the potential

savings associated with a given option. Each option presented for congressional consideration is

designed to increase the productivity of the billions

of dollars in}’ested annuall} in wat~r resources aiid

water resource management. Issues 1 and 3, f’k- ,

proving Federal Problem-Solving Capabiliti~s,,”

and “Establishing Appropriate Modeling Strategies

Within Individual Federal Agencies, ” are directed

toward making m~re effective use of the approximately $50 million per year spent by the Federal

Government on water resource modeling; issues 2,

4, and 5, “Meeting the Needs of the States, ” “Pro-

. . ~:-; ,+-7 . .... -r

. ., .S . - . ., ,

~idm%x~&*~. uwr~ wi&ff&at\on A~uf ~-,, ;

jsting M&&‘ ‘ and “FMk%al Support for Moda~~

Rel@#~.~i@,” focus on impro~.ing modeling

cap@M1~Kkt&&.tgh the provision of augmented

mo@l-~@?t@;#&+ici#. ~

, > - ..-, +, ., ,

,,~ . * , .<- .., %:. ,. ,, ,

‘-’~i~~~z Improving Federal

..-. “l%6!@3&&i_Solving -4—’==. %+5 .=. + Capabilities

= - -=, -..= --=-+ ~ ;:+ . >Z+c: . k ~ .

overall strategy for developing, using, disseminating, and maintaining these tools. Models tend

to be built on an ad hoc basis, in response to immediate problems, rather than as a result of inte-
Ch. 1-summary, Issues, and options ● 11

grated planning. In the absence of any comprehensive model development and support strategy, Federal agencies are often unresponsive to State and

Federal problem-solving needs, or to congressional

directives expressed in water resources legislation.

The OTA survey of Federal agencies reveals

great variation in the use of water resource models.

Although a particular law may assign similar analytic responsibilities to a number of agencies, some

agencies will employ the most sophisticated computer tools available for their analyses, while others

rely primarily on simpler approaches. In some

cases, this may be all that is needed; however, in

many instances, implementation of legislative requirements could be improved by more sophisticated Federal analytic capabilities. While a few

agencies are extensively involved in developing

modeling expertise (e. g., Corps of Engineers and

USGS) most agency modeling efforts vary greatly

from issue to issue, from program to program, and

from decisionmaker to decisionmaker.

Most water resource problems, and the Federal

legislation that deals with them, affect a number

of Federal agencies. However, each agency is individually responsible for developing and funding the

analytic tools it requires. While many models have

widespread potential use among a variety of Federal

institutions, it is often impossible for anyone agency

to commit the personnel and financial resources

necessary to bring them to completion. Developing these tools is expensive and technically complex. For example, the problem of collecting enough

data to fine-tune models and test their accuracy can

inhibit model development by a single agency.Unless clear direction and priority-setting mechanisms are provided by Congress and the Executive Office of the President, the best analytic

tools will not be available throughout the Federal

Government, and many needed models will not

be built or supported.

At present, minimal Federal oversight exists

for the finding of applied research and development (R&D) activities. The mechanisms that

rently exist for coordinating water resources ana “-

“fins almost entirely on research needs. Neith@t%

information required for solving policy problems

nor the analytic techniques needed to aid in decisionmaking are directly addressed in the current

.

process for coordinating the Federal R&D agenda

in water resources. Under the water Research and

Development Act of 1978, the Secretary of the Interior is presently directed to develop a 5- year water

resources research program, drawing on the expertise and advice of appropriate Federal agencies, the

State water resources research institutes, and other

appropriate entities. The program is to indicate

goals, objectives, priorities, and funding recommendations to the President and Congress for water

resources R&D. That document is intended to serve

as the basis for funding allocations in the budget

processes of Congress and the Executive Office of

the President. , While the 1978 act recognizes the need to

strengthen, “The capability for assessment, planning, and policy-formulation , . . at the Federal

and State level, “ it provides no specific direction

to determine what mix of research and problemsolving capabilities can best meet Federal needs.

Moreover, by concentrating primarily on

research needs, it misdirects mission agency

priorities toward research per se rather than

toward coordinated development and utilization

of scientific knowledge and related analytic capabilities. The research focus of the current act

also reinforces tendencies within individual agencies to fund projects that reflect the agency’s mission, rather than priority problems identified by

Congress and the Executive Office of the President.

Options available to Congress include:

Congress could amend the Water Research

and Developement Act of 1978 to specify the development of a multiyear plan emphasizing a

mix of R&D needs, unable analytic tools, and

supp:~ w

mrvices

, ,0 ~@&f~~ mmrring~

 that these tools are

,

... - gers.

Over a dozen reports defining Federal water

resources research needs have been prepared over
12 ● Use of Models for Water Resources Management, Planning, and policy

— . — —-—-——-— —

the last 20 years. 10 The latest of these, the National

Research Council review of the draft Five-Year

Plan specified by the act, lists major water resource

problems, and further states that:

For many of the foregoing problems the basic

and applied research has already been accomplished in substantial part, if not entirely. What

is often lacking, however, is adequate technology

transfer . . . Solution of many other problems requires research and development to advance the

state of knowledge.

The individual agency research plans submitted

for use in developing the Five-Year Plan gave high

priority to the development of mathematical models. Similarly, a 1977 report on research needs

by the Committee on Water Resources Research

stated that, “Throughout this ‘catalog of needed

research, there is a strong theme that calls for continually improving mathematical and physical modeling capability. ‘I 1

As with previous plans, the latest Five-Year Plan

proposal has not been as effective as it might have

been, due to its emphasis on a research agenda.

While models have been acknowledged as important research tools, little attention has been paid to

developing the analytic tools and support capability

needed to meet Federal and non-Federal water resource problem-solving responsibilities. Major

gains in the effectiveness of Federal modeling efforts can be achieved through systematic provision

of such support services as assistance in locating

and obtaining usable existing models, testing and

evaluating models for application to different conditions and decisionmaking needs, and training and

technical assistance in using the models.

Mathematical models are an important component of the water resource analysis needs of Federal

agencies. However, as with other forms of R&D,

creating these tools is only the first step in establishing needed analytic capabilities. Congress could

expand the scope of the Water Research and Devel-

——

~ ~~[>dela[ Walel //esOU7Ce> A Reolew oj the Propo red Flue- year %yarn

Plan, Water Rcsourccs Research Re\iew Cornmlttec, Commission on

National Rcsf)ur( es, National Rescar( h Council: National Academy

Press, 1981

18 DlrectlonJ In (J ~’ W’alo Research 1978-1982, Committee on Water

Resources Research of the Federal Coordinating Council for Science,

Engineering, and Technology (Springfield, Va. : National Technical

Information Ser\ice PB 274278, (Xtohcr 1977),

opment Act to specifically address a broader range

of analytic and problem-solving needs for water

resources decisionmaking, and provide a mechanism (such as an interagency coordinating committee) to carry out the intent of the act.

OPTION l-B:

Congress could establish an interagency unit

whose responsibilities include developing a multiyear plan for water resource analytical needs

and coordinating the implementation of the

plan.

Interagency representation may be necessary for

successful coordination. This unit might be housed

either within the Office of Science and Technology

Policy or in an interagency water resources policy

organization similar to the Water Resources Council or its potential successor. The unit might be

directed to work closely with the Office of Management and Budget for budgetary rev iew.

OPTION l-C:

When addressing priority problems through

legislation, Congress could establish specific

mechanisms to provide adequate Federal water

resource analytic capabilities to meet the intent

of the legislation. .

Congress could explicitly direct Federal agencies

to provide institutional support for the analytic

capabilities needed to implement legislative goals.

A number of approaches could be used for providing these capabilities, including centers of excellence

at universities, operating units within existing Government organizations, and agency and interagency

demonstration programs for creating support units.

Examples of such support units as the Fish and

Wildlife Service Instream Flow Group are described

in chapter 4.

Issue 2: Meeting the Needs

of the States

Most of the Nation’s major water resource legislation is based on the concept of a strong State-Federal partnership for managing and planning the use

and protection of the Nation’s water. If States are

to fulfill their responsibilities, and take on an

increasing share of water resource management

delegations in the future, it is in the Nation’s

best interest to ensure that the States have ac-
Ch. l—Summary, Issues, and Options ● 1 3

cess to, and are capable of using, the best available analytic tools.

Many States depend heavily on Federal agencies for assistance in modeling, and rely primarily

on models that: 1 ) are widely available, 2) have a

long history of use, and 3) are well supported by

Federal agencies. Most States lack the financial

resources and the technical expertise required to

develop models independently. States frequently

share common responsibilities or problems, and can

take advantage of federally developed models designed for application to a wide variety of natural,

social, and economic situations. Even for situations

where differences among States require substantially different models, agencies of the Federal Government are important centers of expertise to which

States. turn for modeling assistance.

However, many of the models that Federal

agencies routinely use are inappropriate to assist

the States in fulfilling their water resources

responsibilities. Even when agencies develop

models that relate to State concerns, they often have

no mandate to assist the States in analyzing their

water resource problems. Consequently, many

States find that such models are too complex to use,

require more input data than States can afford to

collect, or fail to meet specific State analytical needs.

Although a few agencies, such as EPA, solicit

general input from the States through advisory panels or other means, State needs are largely neglected in Federal agency modeling processes.

If State agencies are to utilize Federal models

to a greater extent, practical mechanisms must

be devised for providing State input into the

model development processes within individual

Federal agencies.

In addition, for the Federal Government to be

effective in assisting States to analyze water resource

issues, it must first develop reliable means of obtaining information about State needs. Mechanisms

for assuring State input into Federal R&D processes, as specified under the Water Research and

Development Act of 1978, are inadequate. The current act directs the 54 State (and territorial) water

resources research institutes to develop 5-year research program reports in close consultation with

appropriate State agencies, and to submit these to

the Secretary of the Interior for use in developing

a 5-year coordinated Federal water resources research program. As outlined in Issue 1, ‘ ‘Improving Federal Problem-Solving Capabilities, such

a procedure focuses primarily on water resources

research, and does not give adequate consideration

to developing and supporting analytic tools for solving important water resource problems. In addition, it makes the State water resources research

institutes the primary liaisons between the States

and Federal water resource planning. The institutes, many of which were created by Federal

legislation and operate primarily through Federal

funding, are primarily research centers.

The capacities and functions of the State water

research institutes vary widely, Some compete extensively for discretionary Federal research funding,

while others operate primarily on the small basic

allocation provided to all 54 institutions. Some are

actively involved in pursuing solutions to water resource problems that affect their States, while

others concentrate on scientific problems that may

have few near-term practical ramifications.

Perhaps most importantly, the institutes have a

federally authorized research focus that makes it

difficult for them to adequately account for the applied research and problem-solving needs of State

and local water resources agencies. While they play

a vitally important role in the long-term development of expertise, the institutes are in a relatively

weak position to voice State agency needs to the

Federal Government.

Two additional pressing needs identified in the

OTA survey of State water resource agencies are

discussed in detail under issues 4 and 5: 1) better

access to information about existing models; and

2) increased training opportunities in model use for

State personnel.

Options available to Congress include:

OPTION 2-A:

Congress could direct the States to designate

a lead State agency to assist the Secretary of the

Interior, or other designee, in developing a multiyear plan for water resource analysis needs.

The Water Research and Development Act directs the State water resources research institutes,

in consultation with State agencies, to provide input to the Five-Year Plan mandated by the act. If
f4 ● use of Mode/s for water Resources Management, planning, and policy

the Federal Government is to assist States in meeting water-related responsibilities, it must take into

account a wide range of State water resource agency

information and analytic needs. Congress could

amend the act to allow the States to designate a lead

State agency or a water resources research institute

to participate in planning a broader multiyear Federal agenda.

OPTION 2-B:

Congress could strengthen the States’ own

capabilities to undertake sophisticated water*

source analysis.

As the States’ water resource management responsibilities have increased, so have the States’ requirements for sophisticated water resource analysis. Improving the States’ own analytic capabilities, either through federally sponsored training or by funding the States to develop and use their

own analytic tools, could allow States to be less

dependent on Federal agencies for analysis.

For example, the Clean Water Act (Public Law

95-217) directs the Administrator of EPA to make

grants to planning agencies to develop a comprehensive water quality control plan for a river basin.

Congress might consider, similar programs for water

resource development programs. If the States are

to assume a greater role in the priority-setting process, Congress might consider including formula

funding to strengthen States’ analytic capabilities.

OPTION 2-C:

Congress could direct Federal water resource

agencies to respond to the analytical needs of

the States whenever States are to implement

Federal programs.

For example, under the Safe Drinking Water

Act, the States have primary enforcement responsibility for public water systems. The act specifically

directs the Administrator of EPA to conduct research and demonstrations of improved methods

(i) tO identify and measure the existence contaminants in drinking water (including methods which

may be used by State and local health and water

officials), and (ii) to identifi the source of such contaminants.” One activity undertaken by EPA—

funding the Holcomb Ground Water Model Clearinghouse—helps the States obtain ground water

quality models used to identify the transport and

fate of pollutants.

,.4 - : .

--- — -- . . - ,

Many of the major Federal water resource

agencies lack an intergratedplan for developing

and supporting models. These agencies general-
,

. Ch. l—Summary, Issues, and Options ● 15

ly develop models in response to an immediate need

to solve particular problems. Few attempts have

been made to integrate related modeling efforts

within each agency. Moreover, many models are

produced without serious attention to decisionmakers’ needs or significant managerial input.

Models may not have been tested to determine their

ranges of error and applicability to different conditions, and model assumptions and results may

not be explained well enough to allow decisionmakers to interpret them properly. Consequently,

some agencies may have a multiplicity of models,

only a few of which are actuaIIy usable.

A few Federal agencies or offices, however,

have established comprehensive strategies for

developing and supporting models. These strategies generally take two different forms,: 1) develop=

ing the capacity to analyze priority water resource

problems encountered by many users, through a

limited number of carefully selected models; or

2) developing a general capability for analyzing

individual problems on a one-time or limited basis.

Each involves different mixes of model development

and support activities.

Outstanding examples of both modeling approaches currently exist within the Federal Government. The Hydrologic Engineering Center (HEC)

has extensively developed the capacity to maintain

and support 12 Corps-built models. HEC support

services include training in model use and technical

assistance to users. EPA, upon the completion of

its Stormwater Management Model (SWMM), es?

tablished the SWMM Users’ Group to encourage

the model’s dissemination and use. Since its inception in 1973, membership has grown to over 500

users, who meet to exchange information and ideas

relating to the model's use, assist each other in running it, and explore alternative analytic tools. A

description of HEC and SWMM User Group activities is provided in chapter 4 of this report,

Developing selective modeling capabilities can

bean effective strategy when frequently occurring priority problems appear’ to be solvable

with some kind of standard technique. Models

for dealing with these problems are generally

developed in anticipation of repeated application

by a variety of users. Their design must give close

attention to user needs and capabilities. Models

must be thoroughly explained, or documented, tested

for use over a wide variety of conditions, easily accessible, and usable on many different computer

facilities without ma@ modifications.

To assure that the models are widely and appropriately used, the sponsoring agency must further

develop a coordinated program of user support

services, including;l) training programs—with

“hands-on” instruction, if possible; 2) one-on-one

technical assistance, for problems that arise in the

course of running the Model and interpreting its

results; and 3) model maintenance, to incorporate

improvements and assure that users are informed

of such modifications: -

, :,J s

Agency expenditures support of such a program need not be large .Services for frequently used

models are often provided by the private sector on

a paid COnsultant basis. Agencies may need only

to provide rudimentary services, directing users to

appropriate sources of further assistance. However,

the agency would need to ensure that the necessary

support is available of the highest quality.

More general modeling capabilities have been

developed by USGS, which maintains a cooperative

assistance program that provides services on a costsharing,. to over 600 State and local agencies.

To meet the requirements of these dispersed users,

USGS maintains numerous models that can be

adapted,.by its staff to specific local situations.

USGS model-related activities are described in detail in chapter4 of this report. The diversity of user

ed

.

ne s, particularly for ground water modeling,

makes this approach particularly helpful for assisting non-Federal agencies lacking inhouse model- . .,

ing capabilities.

For users with unique information and analytic needs,developing standard models to an-

%

*Jpat.;~:2 ,=

~ needs may be inappropriate. In

t$@~,SJ@#J~”$,JriS, strategies emphasizing general

@~~@#@#~tiesS which stand in readiness

~3@~@!,~~@Wt a model appropriate to each

WW#,S,##@+@~ needs , may be more effective,

Such a strategy requires personel capable of

routinely coordinating model development, bringing scientific knowledge and modeling expertise to

bear on unique situations. While the individual
16 Use of Mode/s for Water Resources Management, planning, and policy

— —

models require appropriate support (e. g., adequate

testing and documentation), the process focuses on

the needs of a single decisionmaker or decisionmaking group, rather than on those of many dispersed

users. Developers must work closely with the user

to adapt the model to the particular issue, test and

apply the model, and interpret its results.

Developing comprehensive strategies for

building and disseminating water resource models is a pressing need for each of the Federal

agencies involved in this field. Decisions on what

kinds of modeling capabilities to develop, and what

levels of funding to allocate in support of them, need

to be made at top policymaking levels within each

agency for the agency as a whole, taking into consideration its present and future responsibilities, and

its role in providing other Federal, State, and local

government entities with assistance in model use.

While issue 1 addressed strategies for improving

interagency coordination of water resource modeling activities, long-range intra-agency planning for

the models and related support services within each

agency’s purview must supplement interagency coordination efforts.

An option available to Congress includes:

OPTION 3-A:

Congress could, through its oversight responsibilities, direct each of the major Federal water

resource agencies to develop a coordinated strategy for the development, dissemination, and use

of models.

OTA case studies indicate that coordinated planning is necessary for providing effective institutional

support to encourage model development, dissemination, and use. While the approaches used in existing programs differ widely, successful efforts have

two elements in common: 1) the models are of high

quality, have been evaluated over a wide range of

conditions, and are responsive to users’ needs; and

2) the models are well documented and maintained,

easily accessible, and are associated with adequate

technical assistance. Oversight activities to ensure

the development of a strategy incorporating each

of these elements could help promote a more effective problem-solving capability within Federal agencies.

Two elements that are integral to the development of comprehensive modeling strategies—training and the availability of information about models

—are discussed below as issues 4 and 5.

Issue 4: Providing Potential Users

With Information About

Existing Models

Many models currently developed by Federal

agencies are intended for a single application—once

they have been built, and are used to analyze a

single problem, they are considered to have served

their purpose, and are shelved. Since they are not

designed for distribution, information on their existence is not typically made available outside the

agency. Consequently, other agencies with potential uses for these models may be unaware that such

models even exist. Often the models are not tested

to determine their accuracy and applicability to

other situations, nor are they sufficiently documented so that others may choose to use them.

Models developed by outside contractors, but which

are left undocumented or are documented inadequately, may not even be usable by other personnel within the same agency.

No entity within the Federal Government is

specifically charged with providing information

to potential users—Federal or non-Federal—

about the governmentwide availability of water

resource models. Three existing units provide such

information as part of a more general mission; each,

however, is limited in its ability to gather comprehensive information on existing Federal models,

rapidly access that information for users, and match

user needs to available models.

The Water Resources Scientific Information

Center (WRSIC) has supported two major sources

of water resource information, Selected Water

Resources Abstracts, and the Water Resources

Research in Progress File. Both have provided reference services geared to trained water resource

professionals— information on modeling activities

is included, but not in a format that allows for ready

access to specific types of models. Moreover, the

services do not reference models or documentation

directly. They can at most identify publications in
Ch. l—Summary, Issues, and Optjons ● 1 7 —...— ——— —————————— ————

which models are cited or described, or ongoing

research projects that involve modeling activities.

Recent cost-saving initiatives are projected to substantially curtail WRSIC activities, particularly in

the area of printed material; however, computerbased information retrieval services for accessing

published work are expected to be maintained.

The National Technical Information Service

(NTIS) collects and sells data files, computer programs, and model documentation manuals from

Federal sources. The sheer magnitude of the NTIS

mission— responsibility for disseminating over 1

million publications—makes it extremely difficult

for NTIS to provide detailed assistance to potential computer model users. Its information retrieval

system is not well suited for locating available computer tapes of models. Recently, NTIS files of computer tapes have been combined with those of the

General Services Administration’s Federal Software

Exchange Center (FSEC).

FSEC serves as a central repository for computer

programs that Federal agencies consider to be widely applicable. Its holdings span an extremely wide

range of subjects, and water resource models comprise only a small portion of the available software.

Since FSEC has a very limited staff, it cannot assist

users in determining the capabilities and limitations

of its models, running them, or interpreting results.

Moreover, agencies provide models to the Center

on a purely voluntary basis, and FSEC regulations

prohibit the Center from identifying the agency that

developed the model to potential users without the

agency’s expressed consent. Lacking access to the

individuals who developed the model, users may

have difficulty in applying it to the problems they

need to analyze. The organization’s inability to provide user support limits its primary utility to professionals with highly developed modeling expertise.

All of these organizations provide information

on models that have been documented and supplied

to them by various Federal agencies. However,

many Federal models are not entered into any of

these systems, and many that have been entered

have been inadequately documented.

A number of attempts have also been made at

agency levels to provide relatively detailed information on models dealing with specific subject

areas. Two of the larger systems dealing with water

resource concerns are the Department of Agriculture’s Land and Water Resources and Economic

Modeling System, and the EPA Center for Water

Quality Modeling, both of which are described in

detail in chapter 4 of this report.

In recent years, the concept of a model clearinghouse has gained many adherents in the scientific

and managerial community. Such clearinghouses

would be designed to organize models for easy

access by users with specific analytical needs.

To test the utility of the clearinghouse approach,

EPA has sponsored the development of the International Clearinghouse for Ground Water Models

(ICGWM) at the Holcomb Research Institute. An

extensive description of ICGWM is provided in

chapter 4 of this report. Preliminary findings indicate that ICGWM has been very successful in improving the accessibility of ground water models.

Clearinghouses, however, remain a controversial

approach. Some water resources professionals are

skeptical of their cost effectiveness, and of any one

organization’s ability to provide expertise about

large numbers of mathematical models.

options available to Congress include:

OPTION 4-A:

Congress could direct the Federal water

resource agencies to make information on agency models available to outside users and to establish mechanisms to distribute these models

on request.

Several water resource agencies have already established catalogs of existing models, but on the

whole, it is extremely difficult to obtain information about the existence and specifications of federally developed models. This information is generally

unavailable to potential users in local, State, or

other Federal agencies.

A second component of information transfer is

the dissemination of the computer program for the

model. Such programs are also generally difficult

to obtain. One office with extensive capabilities for

distributing models to potential users is HEC,

described in chapter 4. Congress could direct agencies that do not presently distribute the results of

federally funded modeling activities to do so at reasonable cost to the user.
18 ● Use of Models for Water Resources Management, Planning, and policy

OPTION 4-B:

Congress could expand the role of existing information transfer agencies to be more responsive to the modeling information needs of water

managers, and encourage water resource agencies to use these existing mechanisms.

Either FSEC or WRSIC could be expanded to

serve as a Federal Government-wide repository of

water resource models and model information.

Each of these groups currently provides limited information about water resource models-FSEC focuses directly on models, but has no water resourcerelated mission or expertise, while WRSIC is a

comprehensive information source for water resource research, with no model-related mission or

expertise. Neither provides the support services required for assisting potential model users.

Water resource agencies would have to be encouraged to assist the chosen information transfer

agency in expanding its services.

OPTION 4-C:

Congress could establish a national clearinghouse system for the distribution of water

resource models.

Though several model clearinghouses currently

exist in the United States, many important water

modeling areas are not covered by any existing organization. The Holcomb Clearinghouse contains

an extensive file of ground water models, and

EPA’s newly established Center for Water Quality Modeling contains information on a few of the

most popular surface water quality models.

Due to the substantial interconnections and overlaps among water resource modeling activities,

many professionals consider it desirable to develop

a comprehensive center to which a water resource

manager could turn to obtain complete information on the availability of models. Such a center

would bring together models developed by the Federal Government, States, and the private sector.

A centralized clearinghouse, or a series of clearinghouses, containing information on models of all

aspects of water resources—quality and quantity

of both ground and surface waters, as well as the

social and economic implications of water use—

could assist water managers to choose amongst the

multitude of available tools.

“Seed money” would be required to start a national clearinghouse, but after several years of

operation, equitably designed user fees could cover

a substantial portion of clearinghouse operation

costs. The clearinghouse should provide, at a

minimum, information about available models. Additional services could include providing computer

programs, or more extensive services such as training courses.

OPtion 4-D:

Cogress could fund an interagency demonstration project to evaluate and compare existing models for a representative range of field

conditions. 

Though thousands of water resource models are

 currently available few have, been evaluated for

conditions other than those under which they were

developed. Information about the accuracy of mod-

,-

els is difficult to obtain-and for many models is

nonexistent. Poor validation of models is a major

complaint of potential users and a significant constraint on model use.

source community professional societies might be

willing to jointly undertake the project. The results

of these evaluations would assist professionals in , ,,.$ ~ ~;:,:

choosing tools appropriate to their needs, and give

decisionmakers greater confidence nce in the results. .: . . ., .,. .. - ,

,.

If the demonstration program is successful, a

more formal mechanis for interagency mode l

evaluation might be established. , ::. . . ; .

interpret water resource models. However, Federal, State, and private sector personnel reported

that the inadequacy of current levels of model-
.

Ch. 1-Summa#y, Issues, and Options ● 19

.

related training is a major impediment to meeting the needs of local, State, and Federal agencies. State water resource professionals considered

increased federally sponsored training opportunities

to be a top priority. In addition, officials of Federal

agencies that sponsor training programs acknowledge that inadequate resources are presently provided for training nonagency personnel, and that

current agency training opportunities fall far short

of demand. If models are to be used effectively in

water resource analysis, training in basic concepts

of modeling and in proper interpretation of model

results must be offered to decisionmakers at all levels of government. Finally, ’Federal support for the

academic training of future water resource professionals has been threatened by recent cost-saving

initiatives.

There are three major aspects to model-related

training: 1) general educational opportunities in

water resources research and analysis; 2) specific

training in the use of individual water resource

models; and 3) continuing education for manager/

decisionmakers and users. Each involves a different

kind of Federal training support.

Educating water resources professionals involves extensive academic training and requires

support for research and related overhead. Since

1965, the Office of Water Research and Technology

(OWRT) of the Department of Interior has sponsored the University Water Research Program. The

program provides seed money, through the State

water resources research institutes, for training

students in water-related studies and providing

equipment for students and faculty research work.

Individuals who benefit from the program may become m&M developers, or water resources managers, or analysts who use water resource models.

Federal expenditures for the program amounted to

approximately $11 million for fiscal year 1980.

Funding has been provided on a matching basis

(

phOtO credit: Ted Spiegel,1982

A hydrologist at USGS headquarters In Reston, Va., instructs staff in the use of one of the agency’s.

streamflow models at a desktop computer terminal
20 ● Use of Models for Water Resources Management, Planning, and policy

with State governments, which contributed over

$17 million to the institutes during the same fiscal

year. Over the past 16 years, the program has made

a significant contribution to alleviating the shortage of qualifled technical manpower for water resource management. Federal appropriations for the

University Water Research Program for fiscal year

1982 have been reduced to approximately $6 million. The fate of the University Water Research

Program is still uncertain. OWRT has been scheduled for elimination, with its responsibilities to be

transferred to other offices and programs, before

the end of the current fiscal year.

Model users require specific training to enable

them to use a particular model and apply it to

actual problems. Such training is a critical component in transferring modeling technologies

from the developer to the organizations charged

with solving water resource problems. Many

models go unused, or are underused, because such

training is not widely available. USGS and HEC

are among the Federal agencies that presently conduct training courses in model use—HEC training courses reserve approximately 10 percent of

classroom places for State and non-Corps of Engineers Federal personnel in 24 weeks of formal training programs per year. These courses have greatly expanded the use of HEC and USGS models,

and improved the proficiency of water resource professionals in using them. While both agencies

strongly support the concept of one-on-one training and “hands-on” workshops in model use, the

cost involved in providing these forms of training

limit their present use. Using a different approach

from that of HEC, the SWMM User’s Group provides such assistance informally, or on a fee basis

among members. Use of the SWMM model has

become so widespread that a number of universities

around the country have begun to provide training courses in its use; EPA has not been obliged

to provide formal training instruction since the fall

of 1976.

Short training courses in a number of the more

widely used models are available through public

and private universities. These courses are highly

valuable in providing users with the information

necessary to operate models and interpret their

results.

Managers and decisionmakers are often unprepared for the problems and complications associated

with model use for water resource problems. Many

have completed their formal education prior to the

widespread use of computer modeling techniques,

and do not understand the concepts underlying

computer-based simulation and analysis. Few Federal agencies have yet made a significant commitment to decisionmaker education and retraining to accommodate modeling techniques.

The Instream Flow Group currently conducts an

executive training program to enable field personnel and administrators to use model-based recommendations; ICGWM has recently begun a series of ground water modeling workshops, the most

introductory of which discusses the application and

limitations of models for policymakers and decisionmakers. Nonetheless, Federal efforts to provide continuing education in model use for managementlevel personnel are still in very early stages.

Options available to Congress include:

OPTION 5-A:

Congress could allocate resources to water

resource agencies specifically for establishing inhouse and extramural training programs for

their personnel, and for water managers in State

and local agencies.

Two types of training programs are needed:

1) courses on the use of specific models for potential model users; and 2) continuing education for

managers and decisionmakers to understand t: e

strengths and weaknesses of model-based analyses.

Several examples of training programs are described in chapter 4. These range from courses offered by HEC to the informal conferences of

SWMM’S Model User’s Group. While excellent

examples of training programs exist for agencies

to follow, the need for additional programs is great.

A variety of approaches could be used for developing adequate training programs. Agencies could

arrange to fund training provided by universities

with acknowledged expertise in water resource

modeling, or develop inhouse training capabilities

through agency personnel or outside contractors.
Ch. l—Summary, Issues, and Options ● 2 1

OPTION 5-B:

Congress could expand the current programs

assisting university-level water resources education.

Training grants to universities, and research

grants that provide the opportunity for students to

obtain experience in analyzing water resource problems, are two mechanisms by which Congress can

help provide an adequate supply of well-trained

professionals.

Educating students in state-of-the-art analysis

techniques, often available at universities throughout the country but not within Federal, State, and

local agencies, brings these techniques to the agencies when these students graduate and are hired.

Research and training programs offered through

the National Science Foundation and OWRT are

important mechanisms for meeting future agencylevel analytical needs.
,

Chapter 2

Introduction to Water

Resource Models
Contents

Page

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Introduction to Water Resource Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Water Resource Issues ● ***... ● **.*.** .***.... ...*...* +....... . . . . . . . 30

Case Study of Model Use: Water Resources in Long Island, N.Y. . . . . . . . . . 40

Tab&No.

1. Specific Resource Issues

Fipre No.

FIGURES

1. Inadequate Surface Water Supply and Related Problems..

2. Surface Water Pollution Problems From Point Sources . . .

3, Surface Water Pollution Problems From Nonpoint

4. Ground Water Overdraft and Related Problems . .

Sources

. . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

TABLE

Report . . . . . . . . . . . . . . . . . . . . . .

Page

26

Page

32

36

37

38
Chapter 2

Introduction to Water Resource Models

INTRODUCTION

The Nation’s water resource policies affect many

domestic problems in the United States today—

energy, the environment, food production, regional

economic development, and even the international

balance of trade. As the country grows, excess water

supplies diminish, and it becomes increasingly important to manage existing supplies with the greatest possible efficiency. Americans are demanding

more water—and cleaner water—for households,

industry, agriculture, energy development, recreational use, and aquatic life. For many areas of the

country, the availability of adequate water supplies

is a limiting factor in residential construction,

agricultural production, and economic development

in general.

As the Nation approaches full utilization of its

water resources, water resource management is becoming more complex. Different kinds of uses, and

user groups, increasingly compete for limited supplies. Moreover, interconnections among virtually all aspects of water systems are increasingly

apparent— stream flows affect underground reservoirs, for example, while manmade civil works,

laws, and relations have profound consequences

for the hydrologic balances of entire regions.

Thus, the ability to manage and plan the use of

America’s water resources—and determine the consequences of resource decisionmaking-becomes increasingly important and increasingly difficult as

well. In recent years, successful management and

planning has increasingly been based on the results

of mathematical models. The information provided

by these tools is used to help make such decisions

as funding flood control structures, planning pollution control programs, or operating water supply

reservoirs.

Leaving aside the mystique of computers and

complex mathematics, mathematical models are

simply tools used to help understand water resources and water resource management activities.

Before the dams and sewage treatment plants are

built, before actions are taken to comply with

regulations, problems must be analyzed to determine an appropriate way to proceed.

This part of water resource management, though

not as apparent as the reservoirs, pipes and sewers,

is a vital component in meeting the Nations water

resource needs. As the desire for more and cleaner

water grows, careful analysis becomes more important. Today, wasting water reduces the amounts

available for others. Over-building dams or sewage

treatment plants wastes money that could be available for other purposes.

Sophisticated analysis, through the use of models,

can improve our understanding of water resources

and water resource activities, and help prevent

wasting both water and money.

This assessment of water resource models is

therefore not an assessment of mathematical equations or computers, but of the Nation’s ability to

use models to more efficiently and effectively analyze and solve water resource problems. The assessment considers not only the usefulness of the technology-the models—but the ability of Federal and

State water resource agencies to effectively use these

analytic tools.

Models have been available to assist water

resources management, planning, and policy for

several decades. In 1959, the former Senate Select

Committee on National Water Resources made one

of the earliest uses of models for policy purposes.

The committee investigated the importance of water

resources to the national interest, and considered

the Federal activities required to provide the desired

quantity and quality of water. To aid in its investigations, the committee called on Resources for the

Future to develop a model of water supply and projected use for 1980 and 2000.1

During the 1950’s and early 1960’s, many water

resource professionals began to realize the poten25
.

26 ● Use of Mode/s for water Resources Management, p/arming, and pO/iCY

—

tial of models for improving management and planning—but were overly optimistic about the ease

with which these tools could be developed and

adopted for general use. During the 1970’s, as computers became more readily available and the cost

of computation decreased, model development

flourished. However, as often occurs, the technology outstripped the capability of the institutions—

the State and Federal agencies—to support it.

Today, model use is increasing the efficiency and

lowering the cost of water resource management,

but the potential for further improvement remains

great.

The following section of this chapter outlines the

basic principles and functions of water resource

models, and briefly describes the major types and

classifications of the models. A further section introduces the 33 major water resource issues (table

1) for which model use was analyzed and surveyed.

The chapter concludes with a case study that illustrates how models were used to deal with a variety

of water resource problems in the Riverhead-Peconic area of Long Island, N.Y.

Table I.—Specific Water Resource Issues Addressed in Report

.-

Surface water flow and supply

Hydrology:

Flood forecasting and control

Drought and low-flow river forecasting

Streamflow regulation (including reservoirs)

Instream flow needs (fish and wildlife, recreation, hydroelectricity, etc.

Use:

Domestic water supply

Irrigated agriculture

Off stream use (other than domestic and agriculture)

Water use efficiency and conservation

Surface water quality

Nonpoint source pollution and land use:

Urban runoff

Erosion and sedimentation

Salinity

Agricultural runoff (other than erosion and salinity)

Airborne pollutants

Water quality (other than nonpoint source and land use):

Wasteload allocation (point source discharges)

Thermal pollution

Toxic materials

Drinking water quality

Water quality impacts on aquatic life (including eutrophication)

Ground water—quality and quantity

Quantity:

Available supplies and safe yields

Conjunctive use of ground and surface waters

Quality:

Accidental (and preexisting) contamination of ground

water for drinking water (including toxic substances)

Agricultural pollutants to ground water

Movement of pollutants into and through ground waters

from waste disposal (landfill siting, injection, etc.)

Saltwater intrusion

Economic and sociai

Economic:

Effects of water pricing on use

Economic costs of pollution control by industrial sector

Benefit/cost analysis

Regional economic development implications of water

resource policy

Social and integrative:

Forecasting water use

Social impact analysis

Risk/benefit analysis

Competitive water use demands (by region, by sector

and water quality objectives

Unified river basin planning and management

SOURCE: Office of Technology Assessment

‘-a

INTRODUCTION TO WATER RESOURCE MODELS

What are water resource models? Briefly, they

are analytical tools used to determine the consequences of proposed actions or forecast the quantity or quality of the water in the Nation’s rivers,

lakes, or ground waters. These models, which range

in sophistication from simple work with a desk calculator to complex computer programs, are the scientific community’s way of understanding and predicting the workings of a water system. Models are

used to synthesize and analyze the substantial

amounts of water quality, quantity, and societal information needed for effective planning and management, Effective models condense large amounts

of data, simulate the physical and biological dynamics within a water body, or suggest solutions that

are most equitable to competing water users.
Ch. 2—introduction to Water Resource Models ● 2 7

A model is a ‘‘numerical representation’ of how

the real world or some part of it—a lake, a dam,

or a community—works. More precisely, a model

uses numbers or symbols to represent relationships

among the components of these real-world systems.

A river basin, for example, is composed of water

flowing in natural (and manmade) channels, and

may have dams that generate electricity and create

water impoundments. The river’s waters are often

used by domestic, industrial, and agricultural consumers within the basin. The basin normally contains a wide variety of aquatic and related wildlife,

and may attract numerous users of recreation and

recreational facilities. All of these may be considered

components of a river basin system; if they can be

meaningfuhy quantified, they can be included in

a mathematical representation, or model, of the

river basin.

Models deal with the interrelationships among

the components of a system. For example, the decision to store water behind a dam will increase (or

maintain) the size of a lake behind the dam, and

decrease the amount of water flowing below the

dam and the amount of electricity generated at the

site. The action may increase the number of fish

in the lake, attracting more fishing enthusiasts, and

reduce the level of water in a marsh downstream,

inducing birds and other wildlife to migrate elsewhere. Models are simply series of equations that

express such relationships in mathematical form.

Photo credit: @ Ted Spiegel, 19S2

In addition to generating hydropower, this dam helps to control streamflow on the lower reaches of the river, and

assure adequate water supplies in time of drought. Achieving the multiple objectives involved in reservoir management

can be significantly improved and simplified through the use of management-related mathematical models
28 . Use of Models for Water Resources Management, Planning, and policy

—

To take the illustration a step further, if a model

accurately represents a system, it can be highly useful in analyzing conflicts among different objectives

for managing that system, or ways in which management objectives are complementary. For ensuring adequate water supplies in times of drought,

reservoirs must retain as much water as possible.

But to control floods, unused storage capacities of

reservoirs must be available to receive excess flows.

Mathematical expressions are used to represent the

quantity of flood waters that can be stored when

a given amount of water is being held in reserve

for water supplies.

A model is necessarily a simplification of the system it describes. It would not be possible to construct a model that accounted for all the minute interactions of a complex system—but perhaps more

important, it would not be useful to do so, either.

A model’s value as an analytical tool lies in its ability to reduce the number of factors to be considered

to a manageable size, selecting the most significant

interactions in a system, and assuming that other

factors have negligible effects.

Models of how pollutants are transported in a

river are good examples of the need for simplifying assumptions. In reality, the flow of a river is

three dimensional-the river moves and pollutants

are dispersed in all directions. It is often prohibitively complex to represent three-dimensional pollutant transport, however; most river models are designed to describe the transport of pollutants in only

one direction—downstream—and ignore vertical

or across-channel flow. For purposes of predicting

the concentration of pollutants at a location far

downstream, i.e., at a drinking water intake pipe,

at a specific time, these influences on pollutant

transport are negligible.

To determine if model assumptions—like those

made for pollutant transport—are valid, model

results are tested against actual measurements. For

example, if the model’s forecast of the time of arrival and the concentration of pollutants at the downstream intake pipe is close to the concentration actually measured at that time, it would appear that

it is valid to make these assumptions, at least under

these conditions. Usually, in validating a model, as

this process is called, the model is compared with

actual measurements under a variety of conditions.

If a model is found to be a reasonable representation of the real system, it can serve a number of

functions. First, it can be used descriptively to aid

analysts in understanding how the real system

works. By way of illustration, when a landfill leaks

pollutants into ground water reserves, a model can

be used to show how far the contamination has

spread, and to estimate pollution levels in a given

area. Since these factors can only be measured by

time-consuming drilling of test wells, the model provides the quickest indication of the extent and seriousness of the problem. The insights gained from

the model can then be used to determine the probable location of the most contaminated sites, so that

detailed field calculations can be made in those

areas.

Models can also be used as Predictive tools. In a

river, for instance, dissolved oxygen levels depend

to a large degree on levels of bacterial activity,

because as organic matter bacterially decomposes,

the bacteria consume dissolved oxygen. Dissolved

oxygen concentrations also depend on the exchange

of oxygen between the river and the atmosphere,

algal photosynthesis and respiration, temperature,

sunlight, and many other interactions. Experiments

to determine the direct effects of pollution on dissolved oxygen levels would require inducing many

different levels of pollution into the river, attempting to keep all the other factors constant, and measuring the result. The experiment would be timeconsuming, costly, and difficult to control; moreover, it may be highly undesirable to run such an

experiment in the real world. Because equations

that represent the major factors in determining oxygen levels can be easily manipulated, models can

predict the direct effects of various pollution levels.

These models can be used to determine what levels

of sewage treatment will be necessary for meeting

water quality standards before a sewage treatment

plant is built.

Often, however, it is not sufficient to predict the

consequences of a single event or series of actions.

Preventing floods on a river system, for example,

involves opening the floodgates of a dam to a particular position in order to release the greatest possible amount of water without flooding downstream

areas. Yet if a river system had 10 floodgates, and

each floodgate had only 10 positions, a river man-
Ch. 2—introduction to Water Resource Models 29

ager would be faced with 10 billion ( 1010) possible

choices (or combinations) of floodgate settings to

choose from in the event of a flood. Assuming that

a computer model can predict the amount of water

that will be released by a particular combination,

and the impact of the release downstream, in about

half a minute, evaluating all the possible floodgate

settings would require approximately 10,000 years.

However, models can also be designed as optimizing tools that use mathematical logic to determine

the best available choice of settings that satisfies the

requirements.

The models analyzed in this report address a

wide range of water-related issues. These issues can

be organized into four broad categories: surface

water flow and supply, surface water quality,

ground water quality and quantity, and economic

and social.

The category of surface water flow and supply includes surface hydrology and water use. Hydrology

refers to physical factors that influence the movement of water in rivers and streams. Use, in this

case, means water that is withdrawn from a stream

for a specific purpose.

Surface water quality issues are divided into point

sources (e. g., discharges from a factory) and nonpoint sources (e. g., agricultural runoff).

The third category contains issues pertaining to

ground water, including available supply and quality with respect to intended use. Also included in

this grouping are factors relating to the possible interactions between ground and surface water resources.

Economic, social, and interrelated factors fall into

the fourth and final category. Included are the economic and/or social factors that might influence,

either directly or indirectly, the availability, quality,

or demand for water resources.

In further categorizing models, it is often useful

to distinguish between two major benefits that

models can provide: 1) delivering information more

efficiently than was previously possible; and 2) integrating data to create information that would not

otherwise be available. Models that perform the first

function rely on established methodologies (e. g.,

traditional engineering formulae) but use the computer to speed calculation. Models that produce

otherwise unavailable information incorporate

methodologies that require computer assistance for

their execution.

Water resources models can also be characterized

by the purpose for which they are used. These include: 1) operations and management; 2) planning;

3) policy development; 4) regulation; and 5) data

management.

Models for operations and management are used to

support short-term managerial decisions. These

models might be used to control the operation of

a sewage treatment plant or to regulate waterflows

through a system of reservoirs within a river basin.

Models that support Planning activities are often

broader in scope than operations and management

models, as they are used as an aid to medium-range

decisionmaking. Planning models might be used

to evaluate alternatives for future expansion of a

treatment plant or to study the impact of the proposed development of a water-consuming industry

along a river or stream.

Models used for long-range planning would fall

under the class of policy development models. Policy

models might be used to estimate the effects of

energy development on western U.S. water resources.

Models for regulation are those used in direct support of enforcement or promulgation of standards

or in the issuance of permits. For example, a regulation model might be used to determine the allowable

discharge level for a sewage treatment facility prior

to the issuance of a permit for facility expansion.

Some models are developed solely for data management-organizing and accessing data. These models

usually are supported by extensive monitoring and

reporting networks, and may include data for a

wide range of water-related issues.

Yet another method to classify models is by their

technical characteristics. Two of the technical categories most germane to this report are: 1) prescriptive v. descriptive models; and 2) deterministic v.

probabilistic models.

Descriptive, or simulation, models “describe” how

a system operates, and are used to determine

changes resulting from a specific course of action.
30 . Use of Models for Water Resources Management, Planning, and Policy

They are often used to test alternative plans until

a satisfactory option is found.

Prescriptive, or optimization, models, on the other

hand, “prescribe” a course of action that best meets

a specified objective (e. g., least cost or greatest

water yield). If more than one objective is specified,

these models can be used to describe the tradeoffs

among best solutions for the various objectives.

In deterministic models, the results of an event or

series of events are given as a single number or data

series, without indication of extent of possible error

in the resulting calculations. The quantitative relationships among the parts of the system are fixed—

results are completely ‘‘determined’ by the model

and the data provided.

Probabilistic, or stochastic, models produce data

that are expressed as a range of probable results.

Such models take into account the fact that many

events appear to occur randomly. For example, the

intensity and timing of any particular rainfall event

cannot be precisely predicted, but must be described as a probability of occurrence.

WATER RESOURCE ISSUES

A broad spectrum of activities is involved in

managing water resources. Networks for receiving,

routing, and using rainfall—both manmade facilities and alterations to natural systems—must be

planned, built, and operated. The quality of various

water supplies must be analyzed, regulated, and,

if necessary, improved through treatment and other

management practices. Supplies and qualities of

ground water reserves must be determined, and responsible planning provided for their continued use.

Perhaps most importantly, effective and efficient

strategies must be designed for aiding users to get

the greatest possible benefit from the water they

consume—in agriculture, residential uses, and industry, as well as for recreational purposes and the

protection of natural environments.

Professionals have found modeling useful in virtually all aspects of these activities. Chapter 6,

“Modeling and Water Resource Issues, ” presents

32 of the 33 specific issue areas in water resource

management listed in table 1, and details the manner and extent of current model use for each. A

broad and more general overview is provided below, to introduce the reader to the kinds of activities

involved in model-aided water resource analysis and

management. Italicized words or phrases represent

issues specifically analyzed for this report, and addressed in chapter 6.

Perhaps the most striking example of man’s interaction with the hydrologic cycle is flooding. In

addition to the natural potential from spring rains,

hurricanes, and the like, urbanization and other

land-use activities can aggravate flooding problems.

In 1975 alone, 107 lives were lost and $3.4 billion

in property damage resulted from flooding. At the

same time, $13 billion has been spent on flood management and control since 1936.2

To a degree, man has learned to manage floods.

Dams have been constructed that can store floodwaters, releasing them gradually. Stream channels

have been straightened and dredged to transport

floodwaters more efficiently. More recently, nonstructural alternatives, including flood forecasting,

restrictions on building in flood plains, and floodproofing, have received attention. Models have

been widely used to assist in both structural and

nonstructural flood management, including the design and operation of dams and other structural

controls, the delineation of flood-prone lands, and

advanced warnings of floods.

While some areas of the country are plagued with

too much water, other regions may be troubled by

a lack of it. Low rates of precipitation, both

regionally and seasonally, can result in both drought

and low stream flows. The Water Resources Coun -

cil has identified 17 out of 106 water resource

subregions that either have serious water deficiencies at present or are projected to have them by the

year 2000.3 Figure 1 illustrates the regions projected

‘U. S Water Resources Council, 73e Nation Water Resources

1975-2000, (Washington, D. C.: U.S. Government Printing Office,

1978). (Hereafter: WRC, 1978).

‘Ibid.
Ch. Z—Introduction to Water Resource Models . 3 1

to experience surface water supply and related problems through 2000.

Models similar to those used for flood forecasting

and control can estimate the frequency, timing, and

extent of droughts or low flows. This information

can assist reservoir managers in preparing for potential conditions of limited water or in instituting

appropriate conservation measures prior to periods

of water shortage.

Streamflow regulation is often associated with

tradeoffs among competing objectives. For example, storing reservoir water for droughts may reduce

the availability of water for downstream fish and

wildlife habitats. Reservoirs must be operated to

meet often-conflicting multiple objectives. Models

can help evaluate the tradeoffs among these objectives, so that managers can determine an equitable

strategy for operating reservoirs.

Conflicting objectives for water are not limited

to reservoir operation; intense competition between

instream and offstream uses also exists. Instreamj70w

needs include adequate water for fish and wildlife

habitat, recreation, navigation, and the generation

of hydroelectricity. Offjstream uses include irrigated

agriculture; domestic water supply; and water for

manufacturing, minerals, and energy production.

When water is withdrawn from streams in the

United States, about two-thirds is returned; the

one-third not returned is termed ‘‘consumptive

use . Among offstream uses, by far the greatest

consumptive user of water is agriculture. In 1975,

agriculture accounted for over 80 percent of the

total U.S. water consumption.
32 . Use of Models for Water Resources Management, Planning, and Policy

Figure 1 .—Inadequate Surface Water Supply and Related Problems

.

Explanation

Subregion with Inadequate streamflow (1975-2000) Instream use

u

*

●

x

A

SOURCE:

70 percent depleted in average year ● Fish and wildlife habitat or outdoor recreation

70 percent depleted in dry year t Hydroelectric generation or navigation

Less than 70 percent depleted

Specific problems as Identified by Federa/ and State/Regkvra/ Boundaries

Study Teams — Water resources region

Conflict between off stream uses “-...”.”... Subregion

Inadequate supply of fresh surface water to support—

OfLstream use

Central (municipal) and noncentral (rural) domestic use

Industry or energy resource development

Crop irrigation

U.S. Water Resources Council, The Nation’s Water Resources, 1975-2000, Volume 1: Summary, December 1978.

Total withdrawal of water for offstream use is analyses, resulting in major financial and energyexpected to decline slightly by 2000 due to im- related savings, and alleviating demands on scarce

provements in water use efficiency and conservation. ground and surface water reserves. However, while

Significant improvements in the efficiency of irriga- withdrawals are expected to decline by 2000, it is

tion practices have been made through model-based predicted that the annual consumption of water will
Ch. 2—Introduction to Water Resource Models . 33

—— ———.—- ———. —

increase by 27 percent over the same period.4 This

increase in consumptive use will aggravate the conflicts between instream and offstream water uses.

Decisionmakers at all levels of government are

responsible for balancing these competing uses; a

wide variety of models is available to assist the decisionmaker with this charge. Models can assist in

allocating streamflow among conflicting users, and

help forecast future water needs for formulating current policies, long-range planning, and management practices.

Despite the progress made over the last decade,

the effects of municipal and industrial point source

waste discharges on water quality are still widespread. About 90 and 65 percent of the Nation’s

river basins are affected by municipal and industrial

discharges, respectively. 5 Figure 2 illustrates the

regions of the country exposed to point-source surface water pollution problems. Models can estimate

the ability of streams to assimilate pollutants from

these various point sources so as to meet receiving

water quality standards. Such wasteload allocation

models are extensively relied on for planning

purposes.

Therma/ additions from electric power generation

and manufacturing sources elevate stream temperatures, and can significantly affect aquatic life if the

temperature rise or rate of change is great enough.

Models are routinely employed to estimate the effects of thermal wastes from existing and planned

facilities.

Dispersed nonpoint pollution sources are equally

significant contributors of contaminants to the Nation’s waterways, and are significantly more difficult to analyze and control than point sources.

Figure 3 illustrates the areas of the country exposed

to nonpoint pollution problems. An Environmental Protection Agency inventory estimates that

about one-third of the oxygen-demanding loads,

two-thirds of the phosphorous, and three-quarters

of the nitrogen discharged to streams comes from

nonpoint agricultural sources. Agricultural runoff, the

most widespread nonpoint source problem, affects

70 percent of the country’s major river basins.6

+ 1 bid

11 ‘ .$ L P .4 .!’a[~ona[ JI kt~r Qua[lt) In~ rotor) — 1‘}77 R@Jrt to (,’on -

<~fj~, f:I’.A-44f)/4-78-f)ol

“It)l(~

Runoff and irrigation return flows contribute high

concentrations of fertilizers, pesticides, herbicides,

sediment, salts, and minerals. Excessive salinity, due

to the leaching of salts from the soil by irrigation

water, may affect receiving waters to the extent that

they cannot be used for irrigation downstream.

Models can be used to help farmers design ‘ ‘best

management practices’ to minimize nonpoint

source agricultural pollutants.

Although erosion, and the resulting sedimentation

in waterways, are natural processes, human activities— in particular, agriculture—have accelerated

natural rates of soil loss. Sediments from erosion

clog waterways and build up in the slower reaches

of streams, lakes, and reservoirs. Sediments also

carry such pollutants as phosphates and pesticides.

Models are widely used to evaluate land-use management practices for minimizing soil erosion, as

well as to assess the transport and deposition of sediments for river management.

Storm runoff from urban areas—containing oil and

grease, lawn fertilizer, garbage, and soil from construction sites—affects half of the Nations river

basins. Models of urban runoff can be used to simulate the quantity and quality of pollutants from

a particular area and to compare the effectiveness

of alternative control strategies.

Airborne pollution is also a source of nonpoint contaminants. For example, the combustion of fossil

fuels produces sulfur and nitrogen oxides, which

have been linked to the phenomenon of “acid

rain. While the ultimate effects of airborne

pollutants are not certain, increased rainfall acidity has led to such effects as the loss of fish in sensitive lakes. Models that deal with acid rain and

other airborne pollution to water are currently being

developed.

Water pollution from both point and nonpoint

sources can have harmful effects on aquatic life. Excessive concentrations of nutrients can cause explosive

growth of aquatic plants. organic wastes, such as

sewage, can reduce oxygen levels in lakes and

streams, adversely affecting fish. Models can be

used to assist biologists in determining the effects

of various pollutants on aquatic life.

Toxic pollution of drinking water is one of the most

serious water quality problems facing the Nat ion

today. The magnitude of the problem is large—
34 ● Use of Models for Water Resources Management, Planning, and Policy

Photo cred/t: G Ted Spiegel, 1932

Fry at left have been raised with only 20 percent of the normal oxygen level of freshwater. The EPA laboratory in Duluth,

Minn., performs experiments like these to determine what conditions are necessary to assure that offspring develop

normally, like those on the right. Models that estimate oxygen levels in water bodies, when combined with Iaboratoty

data, can be used for estimating effects of actual conditions in rivers, lakes, and streams on aquatic life

30,000 chemicals identified as toxic to humans are

presently produced commercially. Many toxicants

are difficult to detect and remove using present

technologies. Extensive potential exists for using

models to trace the transport and fate of toxicants

through the environment, and to test different management approaches for preventing toxicants from

reaching water supplies.

Other agents of water-borne disease also pose

threats to drinking water quality, including bacteria

and viruses. Over 4,000 cases of water-related illnesses are reported each year, primarily from bacterial and viral sources. 7 While surface waters are

extensively treated before distribution to users,

7WRC, 1978.

ground water, which serves up to 40 percent of the

population, is frequently consumed untreated from

individual wells. Toxicology models, which relate

concentrations of hazardous substances to human

health, are used to aid in setting standards.

Stored underground in the Nation’s ground

water reserves is an amount of water equal to 35

years of surface water runoff. Nonetheless, ground

water resources are exhaustible. Aquifers—waterbearing soil or rock— can be overexploited if ground

water is removed faster than it can be recharged.

Ground water ‘‘overdraft’ can result in increased

water pumping costs, declines in streamflow, land

subsidence, and saltwater intrusion. Figure 4 illustrates the regions of the country experiencing

significant ground water overdraft. Assessing avail-
Ch. Z—Introduction to Water Resource Models 35

Photo credit: C Ted Spiege/, 1982

A soil scientist examines damage to cotton crop caused

by excess salinity in the San Joaquin Valley, Calif.
36 ● Use of Mode/s for Water Resources Management, Planning, and Policy

Figure 2.—Surface Water Pollution Problems From Point Sources (municipai and industrial waste)

(as identified by Federai and State/Regionai study teams)

Explanation

Area problem

Area in which significant surface water pollution from point sources

is occurring

Unshaded area may not be problem-free, but the problem was not

considered major

Specific types of point source pollutants

Coliform bacteria from municipal waste or feedlot drainage

PCB (polychlorinated biphenyls), PBB (polybromated biphenyls,

PVC (polyvinyl chloride), and related industrial chemicals

Heavy metals (e.g., mercury, zinc, copper, cadmium, lead)

Nutrients from municipal and industrial discharges

Heat from manufacturing and power generation

Boundaries

Water resources region

Subregion

SOURCE: US. Water Resources Council, The Nation’s Water Resources, 1975-2000, Volume 1: Summary, December 1978.
Ch. 2—Introduction to Water Resource Models . 37

Figure 3.—Surface Water Pollution Problems From Nonpoint Sources

Explanation

Area problem

Area in which significant surface water pollution from nonpoint

sources is occurring

Unshaded area may not be problem-free, but the problem was not

considered major

Specific types of nonpoint source pollutants

● Herbicides, pesticides, and other agricultural chemicals

 Irrigation return flows with high concentration of dissolved solids

● Seawater intrusion

o Mine drainage

Boundaries

— Water resources regio n

● “-..... Subregion

SOURCE: U.S. Water Resources CounciL The Nation’s Water Resources, 197fKW00, WMume 1: Summary, December 1978

able supplies and aquifer yields from individual aqui- In some areas, however, the excessive use of

fers is a pressing need; models are widely used tools ground water has stopped too late. Major drops in

for managing, regulating, and planning the use of ground water levels have caused the land to settle

ground water. Models can be used to design a well or subside, damaging buildings, roads, and railfield for greatest efficiency, to assess the extent of roads, and causing flooding in coastal areas. Sa/tusable supplies, and to predict water-level declines water intrusion-penetration of underlying saltwaters

resulting from alternative development schemes. into the freshwater layer—has also been caused in
38 Use of Models for Water Resources Management, Planning, and Policy

Figure 4.—Ground Water Overdraft and Reiated Probiems

1 I - 1

Explanation

SOURCE: U.S. Water Resources Council, The Nation’s Water Resources, 1975 -2(W0, Volume 1: Summary, December 1978.

coastal areas by excessive pumping. Similarly,

ground water overdrafting may draw poor quality

ground water near the land surface into deeper,

high-quality ground water reservoirs. The likelihood of encountering these problems in a particular

community or region can be assessed with models.

Models can also help to evaluate management strategies to minimize the risk of such occurrences.

Many ground water users are now attempting

to manage the conjunctiue use of ground and surface

waters to assure adequate water supplies. When

available, surface waters are used to meet demands,

while ground water is relied on primarily during

dry periods. Ground water aquifers are often hydrologically connected to surface lakes and streams;

models can be used to analyze their interaction and
Ch. 2—introduction to Water Resource Models 39

aid in their combined management, providing information about both quantity and quality aspects

of ground and surface water interrelationships.

In the past, ground water was generally considered to be a reliable source of high-quality water.

Yet pollutants from many sources enter the ground

water system, though the extent and seriousness of

contamination has only recently been recognized.

Moreover, the ability of aquifers to rid themselves

of pollutants is limited by the slow movement of

ground water.

Accidental ground water pollution frequently

went unnoticed due to the ubiquitous nature of

contamination—from road salt, oil and gasoline,

and other chemical spills and leaks. Waste disposal

has also been a major source of ground water

contamination. Wastes are sometimes injected into deep wells, which, if improperly designed, can

contaminate drinking water. Toxic chemicals have

found their way into ground water from municipal

and industrial landfills and dumps. Seepage from

septic tanks has for many years been recognized

as a major source of bacterial contamination of

ground water. In addition, agricultural pollution of

ground water can occur from pesticides, fertilizers,

and salts leached from the soil by irrigation waters.

Once contamination occurs, the time and cost of

reversing the process can far exceed the cost of

preventing it. Models can be used to estimate the

infiltration of these pollutants into ground water

and the movement of contaminated water through

an aquifer. They also have potential for aiding the

design of waste-disposal landfills and injection wells

to minimize the potential for polluting ground

water.

Shortages of water, poor water quality, and

flooding have obvious effects on society. Perhaps

less obvious are the indirect economic and social

effects that result from efforts to ensure or enhance

water supplies and quality. The construction of a

multipurpose reservoir, for instance, will bring an

influx of construction workers from outside the local

community. A part of the salaries these workers receive will be spent within the community, thus stimulating the local economy. An increased population, however, may also tax the local community’s

ability to provide adequate services such as education or police protection.

Part of the need to consider the social impacts of

many water resource programs and projects stems

from the uneven distribution of benefits and differing perceptions of the effects by various groups.

Models can assist the decisionmaker by both organizing information on the social implications of a

project and determining what social effects may occur and who may be affected.

Closely associated with social impacts are the

regional economic development implications of water

resource policies and projects. A new reservoir

might stimulate increased recreational activities that

subsequently attract new businesses to an area, or

make a region more desirable for siting industries

or utilities. Models have been developed that project changes in the level of local or regional economic activities resulting from water resource programs and projects.

The desirability of a project or policy may often

be studied using a benefit/cost analysis, which attempts

to assess relative economic efficiencies, weighing

the monetary benefits of a project against economic

costs. Models can be used both to assist in measuring the benefits and costs and to undertake the

benefit/cost analysis itself.

The costs to industry of pollution control can also have

economic implications that affect such factors as industry location and national inflation levels. Models

are used to determine the impacts of these costs on

economic indicators like the Consumer Price Index and the gross national product, as well as to

determine the impact of these costs on specific industries.

Since the economic and social effects of waterrelated development extend beyond a project’s immediate location, it is often important to analyze

these effects on a regional basis. Water resource

strategies can be developed through unified river basin

planning and management, in which projected water

use demands, water quality objectives, and numerous secondary considerations, including desired

levels of economic development, are balanced and

coordinated. Models are useful in many aspects of

such planning.

Another analysis that is often necessary in the

project-planning process is the consideration of uncertainty. Risk/benefit analysis weighs the proba-
40 ● Use of Models for Water Resources Management, Planning, and POliCY

bility of some outcome—a flood or drought—

against the benefit that would potentially be derived, for instance, if a reservoir were built to

mitigate the impacts of these floods or droughts.

Models can help evaluate both the risks and benefits

involved in projects to aid decisionmakers in determining acceptable levels of risk.

One influence on present use of water is price;

raising the cost of water can reduce demand in some

sectors, especially agriculture. This economic approach to conservation is particularly important because it can alleviate both the need for construction of expensive, large-capacity structural supply

systems and the necessity for regulating water use.

Models can determine the effects of water pricing on

use by analyzing consumer response to price.

For regional and national analyses, forecasting

water use requires an evaluation of population and

economic growth, employment, industrial expansion, etc. to project future water needs. Models can

estimate future levels of water use both by projecting past economic and demographic trends and by

simulating the relationships between these factors

and water use.

CASE STUDY OF MODEL USE: WATER

RESOURCES IN LONG ISLAND, N.Y.

On Long Island, N. Y., water is a critical resource. Ground water is the sole source of drinking water for the island’s 3 million residents and

is endangered by contaminants from leakage of septic tanks, landfills, and other sources. Along Long

Island’s coast, rapid overdrafting of ground water

has caused the intrusion of saltwater into freshwater

aquifers. In addition, Long Island’s rivers, bays,

and estuaries, foundations of a fishing and touristbased economy, are threatened by domestic and

industrial wastes. In the past, contamination from

these wastes has resulted in bans on fishing and the

closing of public beaches.

In 1970, the Nassau-Suffolk Regional Planning

Board found that the most obvious limit to future

growth on Long Island was the availability of potable water. The board developed a Comprehensive

Land Use Plan, which recommended seeking additional funds to conduct water quality studies on

Long Island, and provided an impetus for more

rational management of the island’s water resources. Soon after, section 208 of the Federal

Water Pollution Control Act of 1972 became the

vehicle for undertaking these further studies and

developing a regional strategy for treating and disposing of domestic and industrial waste. The

.
Ch. 2—introduction to Water Resource Models 41

Nassau-Suffolk Regional Planning Commission

was designated as the local agency responsible for

carrying out this investigation.

In designing a waste management strategy, the

commission relied heavily on models to provide a

quantitative framework for making management

decisions. a While water quality conditions were directly measured whenever possible, the geographic

scope of the island and the expense of drilling test

wells to analyze groundwater conditions precluded

extensive direct measurement. The executive director of the Nassau-Suffolk section 208 study noted

that a wide variety of models was necessary to provide information for evaluating alternative waste

management strategies and plans:

Long Island’s $5.2 million 208 study could not

have been completed without the application of

management, physical, chemical, analogue and

hydrogeological models. These models were necessary to help replicate a 1,200 square mile, geologically complex area. g

The nature of the management decisions facing

Long Island also favored the use of models. To

minimize the environmental impact of a wastewater

treatment plant, for example, it is necessary to evaluate many alternative sites to determine its optimum location. The time and resources available

for measurement limits the number of alternatives

that can be evaluated. Models can help eliminate

less desirable alternatives, focusing time and

resources for detailed field testing on the most feasible sites.

Several options, for example, were available for

managing the wastes of the Riverhead-Peconic area

of Long Island (fig. 5). One or more regional, subregional, or local sewage treatment plants could be

constructed to handle domestic wastes; alternatively, wastes could be diverted to the existing Riverhead plant. One factor in the decision was the relative impact of waste discharges from the various

treatment alternatives. Several options were again

available: dispose of the wastewater in Flander’s

Bay, discharge it into the Peconic River, or inject

8 The Long ~s[and Comjvehenslue i~’aste Treatment .~ana{ement plan, \’o]-

ume 1 : Summary Plan; \’olume 2: Summary, Documentation ( Hauppauge, .N, Y.: .Nassau-Suffolk Regional Planning Board, 1978),

‘Lee H Koppelman, personal commu nicat ion to OTA staff, No\,

24, 198]

it or allow it to infiltrate into the aquifer. The commission also considered nonpoint sources of wastes

and alternative means of controlling them—zoning,

street cleaning, special agricultural practices, etc.

The commission had to use several models to

evaluate the various alternatives. First, to determine the quantity of water and the amount of pollutants originating from nonpoint sources, the commission utilized a water budget model. For a given

quantity of precipitation, this model projects the

amount of water that will infiltrate the aquifer;

return to the atmosphere via evaporation or plant

transpiration; or reach rivers and streams overland.

Changes in land-use practices—particularly the

construction of impervious surfaces, like parking

lots, and the removal of vegetation—alter the proportions of ground water infiltration, evapotranspiration, and runoff. The water budget model can

respond to actual or hypothetical changes in land

use by estimating changes in the proportional distribution of precipitation. In most cases, with increasing development, recharge to the aquifer

decreases, while runoff normally increases.

An increase in overland runoff tends to increase

the load of pollutants discharged—e. g., sediment

from construction areas, grease from urban streets,

and fertilizers from agricultural land. Runoff can

thus contribute a major source of contaminants to

water bodies such as the Peconic River and Flanders Bay. The water budget model can be extended

to estimate the load of nutrients contained in urban runoff and the total input of these nutrients

to the bay. Thus, as a planning tool, the water

budget model can be used to: 1) estimate the effects of altering land-use practices to reduce excess

runoff and ensure recharge of ground water;

2) estimate the effects of altering land-use practices

to reduce sources of nonpoint source contaminants;

and 3) determine the relative amounts of total bay

and river system contamination contributed by

nonpoint sources.

Other models are used to predict the impact of

waste discharges from point sources on the Peconic

River and Flanders Bay. These models simulate

the currents and circulation patterns of these water

bodies and project the transport and fate of pollutants once discharged. Different models must be

used for the river and the bay because of differences

c 1– . I – c -
42 . Use of Mode/s for Water Resources Management, Planning, and Policy

Figure 5.—Riverhead-Peconic Area, Long Island, N.Y.

Calverton

r-~

(n 6“ South

c

m

Peconic

& Flanders Bay ,

*

p econl~swan POnd pon d

Lake

Cedar .7

%

Wildvw30d Lake “charge

w

E l

STP Sewage Treatment Faclllty Alternatives d::::.?. ]

~Bellow S

Pond

SOURCE: The Long Island Comprehensive Waste Treatment Management Plan, vol. 2, figs. 7-27, 7-28.
Ch. Z—Introduction to Water Resource Models ● 4 3

in their currents and circulation patterns. Not all

areas of a bay or river disperse pollutants equally;

e.g., some sections of Flander’s Bay are isolated

from its primary circulation patterns. Since nutrients stimulate algal growth, which can severely

affect water quality, it is advantageous to rapidly

disperse wastewater discharges to the bay. The river

and estuary models can assist in determining an

acceptable location for wastewater disposal.

The river and bay models assume that the growth

of algae in these water bodies depends primarily

on the concentration of nutrients from waste discharge, However, other factors like ‘‘grazing’ of

the algae by herbivorous zooplankton and recycling

of nutrients from decomposing organic matter also

influence algal populations. To account for these

factors, the commission used an ecological model

that simulates algal growth more accurately, The

ecological model more fully explores the impacts

of both point and nonpoint source discharges on

the bay ecosystem.

An alternative to discharging wastewater to the

bay or river is to discharge treated effluents by

either injecting them directly into the ground water

or allowing them to slowly percolate into the aquifer. These approaches have the potential advantage

of recharging declining ground water levels; however, they could also contaminate the ground water.

Several different models were used to assess the impact of recharging ground water with wastewater

in the Riverhead-Peconic area. One model type

projects the effect of recharge on the height of the

water table and the flow and distribution of recharge

water in the aquifer.

A second model describes the way in which pollutants are transported with ground water flow.

This type of model is used to estimate how a leaking septic tank, an injection well, or a recharge

basin will affect ground water quality.

It is important to note that these models are not

designed to make management decisions themselves. Many qualitative and quantitative considerations that affect management decisions are not

within the scope of the models’ analyses. For examPhoto credit: O Ted Spkge/, 1982

Construction crews prepare a wastewater injection well

on Long Island. Wastewater will be pumped directly into

the ground water table to prevent saltwater intrusion.

Prior to construction, models were used to assess the

injection well’s potential to recharge (elevate) ground

water levels, as well as to assess the possibility that

wastewater could contaminate ground water supplies

pie, while a model may help to guide the selection

of an adequate location for releasing treated sewage

outflows in terms of water quality considerations,

it does not consider many other factors, like a site’s

recreation or habitat potential, which are necessary

aspects of the decisi~nmaking process. Models are

virtuall y indispensable, however, for their ability

to both describe and project, in a quantitative

framework, the effects of alternative management

decisions.
Chapter 3

General Issues in Model

Development, Use, and

Dissemination
Contents

Page

Support Services for Disseminating and Using Existing Models Effectively . 47

Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Informing Users of Available Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

User Assistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Maintenance and Improvement of Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Additional Model Characteristics Affecting Ease of Model Use . . . . . . . . . . . . . . . . 52

Issues in the Development and Use of Models . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Interaction Between Modelers and Decisionmakers . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Evaluating Models for Use by Water Resource Managers . . . . . . . . . . . . . . . . . . . . 55

Mechanisms for Assuring Adequate Oversight of Model Development . . . . . . . . . 59

Legal Aspects of Model Use in Administrative Processes . . . . . . . . . . . . . . . . . . . . . 61

FIGURE

FigureNo. Page

6. Comparison of Measured and Computed Runoff for the Storm of

Aug. 2, i963—Oakdale Avenue Catchment—EPA Stormwater Management Model 57
Chapter 3

General Issues in Model Development,

Use, and Dissemination

Models are increasingly used to analyze a wide

variety of resource issues because they can provide

information that is either unavailable from other

sources, more accurate than that provided by other

sources, or quicker and less costly than that provided by other sources. However, as with many

new information technologies, institutions have encountered problems in integrating modeling and

model-generated information with established operating procedures, professional responsibilities, and

channels of communication.

When modeling efforts are supported by public

funds, institutions that develop models have responsibilities for ensuring the availability y and usability

of such tools for other institutions. To effectively

carry out these responsibilities, model-sponsoring

organizations must devise strategies to inform

potential users of the existence of relevant models,

ensure that the model’s purpose and workings are

explained in writing so that decisionmakers can

determine its applicability to a given problem, and

disseminate the model to those who request it. Additional support services include developing programs to train and assist users to operate models

and interpret results, maintaining and improving

existing models, and designing models for ease of

use by other institutions.

The process of developing and using models also

requires extensive consultation between highly

trained technical and scientific personnel on one

hand and mid- and upper-level managers on the

other. Yet decisionmakers are often unprepared to

involve themselves in the modeling process, and

may consequently be uncertain of how to use model

results. Similarly, modelers may be equally unprepared to build models that provide the kinds of

information decisionmakers need. For institutions

to make effective use of models, links must be

created among modelers, model users, and decisionmakers, and effective incentives be devised to

make model development and use an interactive

process among them. Further, institutions need to

develop procedures for evaluating the models they

use, overseeing model development, and assessing

the legal implications and consequences of their

model use.

This chapter reviews the major issues associated

with the development, use, and dissemination of

water resource models. Many of the significant

problems associated with current model use for

water resource analysis are encountered throughout

the modeling profession; they tend to reflect the

newness of the modeling field, and institutional unpreparedness for overseeing, supporting, and guiding model use.

The chapter is comprised of two major secf “ens:

Support Services for Disseminating and Using Existing Models Effectively; and Issues in the

Development and Use of Models.

SUPPORT SERVICES FOR DISSEMINATING AND

USING EXISTING MODELS EFFECTIVELY

Once a model is operational, any potential user quate user-oriented support services, it is likely to

normally needs a great deal of information from remain unused by anyone other than its developer.

the developer if he or she is to become proficient Within the modeling profession, such support servin running the model and interpreting its results. ices are called technology transfer and assistance. This

A model may have been rigorously developed and section discusses those aspects of modeling that aid

thoroughly evaluated, yet in the absence of ade- users in employing an existing model. Five sup47
48 . Use of Models for Water Resources Management, P/arming, and Policy

port activities are treated in depth; the section concludes with an overview of additional model characteristics that are linked to technology transfer capabilities:

● documentation;

● informing users of available models;

● training;

● user assistance;

. maintenance and improvement of models; and

. additional model characteristics affecting ease

of model use.

Documentation

Documentation is the process of setting out explicit written instructions on how to use a model

and interpret its results. Although documentation

is critical to the proper use and dissemination of

models, it is rarely carried out adequately, and is

considered by professionals to be one of the most

neglected aspects of modeling. The lack of proper

documentation prevents potential users from discovering existing models that suit their needs—

causing costly duplication in model development—

and increases the difficulty and cost of using previously developed models.

Documentation has two purposes. First, it provides a nontechnical description of the basic concepts employed in a model, and its limitations. Such

a description must include sufficient information

to allow a decisionmaker to determine whether a

given model is suitable (and available) for a specific

use. Second, it provides technical information on

the basis of which a user/analyst can evaluate, duplicate, and operate the model. Three kinds of documents are generally used to document computer

models:

1.

2.

3.

a detailed description of the model’s purpose

and assumptions;

users’ manuals, which give instruction on running the model—i. e., how to prepare input

to get the desired output; and

programmers’ manuals, which explain the model’s logic and internal functions, enabling the

user to adjust and adapt the model to fit his

particular needs.

Good documentation is difficult to prepare. Modelers and computer programmers usually have a highly developed command of technical computer languages—it is in these languages that they actually

work. Documentation requires translating the instructions written in these languages into clearly

understandable English. The task is not only timeconsuming— a medium-sized computer program

may consist of 4,000 sets of instructions—but it is

also one for which a technical specialist may have

little skill or motivation. The developer of a model

has no inherent need for documentation, other than

as a reminder of what he may forget. Documentation is principally for successive users, and few incentives currently exist for the developer to take user

needs into account in the process of model development,

Consequently, for most models, documentation

either does not exist, or exists in inadequate form,

lacking in detail, and failing to serve users’ needs. 1

Model documentation is typically so brief or poorly

written that the user is forced to resort to a trialand-error approach to learn proper use of the model, or to seek personal assistance from those who

developed the model.

Documentation is the primary mechanism for informed communication among those involved in

modeling efforts—developers, users, analysts, and

decisionmakers. Without it, the purpose, premises,

and capabilities of the model remain obscure, and

it becomes impossible to: 1) decide whether a model

applies to a given problem, 2) operate the model

independently of the developer, and 3) adequately

interpret and use model results. 2 Further, competent documentation is important in facilitating model evaluation by third parties, and in encouraging

continued maintenance and updating to keep models current.

Few institutions encourage proper documentation. Seldom are funds specifically provided for the

documentation phase of model development. Even

when funds are provided, if the funding organization lacks a unit that critically evaluates documentation in the context of using the model, developers

‘S. Gass, Computer .ilodel Documentation A Retleu and An Approach,

NBS Special Publication 500-39, National Bureau of Standards, 1979.

‘G. Fromm, W. L. Hamilton, and E. E. Hamilton, Federa[~ Supported ,Vlathematzca[ .h!ode[s Surue) and AnalYsz~, Gp(l stock

#038 -000-00221-0 (Washington D. C.: Gmernmcnt Printing Office,

1975), p. 44,
Ch. 3—General Issues in Model Development, Use, and Dissemination ● 49

may have little incentive to spend time and effort

on the quality of their documentation work. In most

modeling efforts, documentation is done ‘‘after the

fact, as part of the cleanup operation at the end

of the project, necessitating searches through old

records at a point when both time and money are

in short supply.

Moreover, modelers and programmers have little

professional incentive to produce high-quality

documentation work. Documentation is a long and

tedious process. Most developers see it as noncreative, in that it calls not for analytical or technical

skills, but rather for communicative abilities that

the modeler frequently lacks. At present, documentation is also seen as contributing little or nothing

to the modeler’s standing in his field.

If documentation is to be upgraded, it must become an integral part of model development. The

most efficient mode of creating written documentation is to do so concurrently with the development

of the model—this helps to ensure that the written

instructions accurately reflect the actual computer

program.

Informing Users of Available Models

Although numerous models are available to assist

water resources managers, these models are difficult

for users to identify, locate, and obtain. OTA found

that many potential model users, and even modelers

themselves, considered the need for effective communication about existing models more important

than the need for developing new models. Frequently, the difficulty of identifying and locating

a suitable model causes the decisionmaker to either

forego model use for water management decisions,

or leads to the development of a new model. Developing new models is extremely costly and timeconsuming, while existing models that have been

evaluated may need only minor adjustments and

‘ ‘fine tuning’ to be applied to the user’s problem.

Presently, most information on existing models

is available only in technical journals. These technical publications are geared primarily to use by

scientists and modelers. Few journals aim to communicate with decisionmakers and managers, and

their distribution is often limited to a handful of

subscribers. Most take over a year to publish a submitted manuscript, causing significant delays in

communicating the availability of a model.

Three ways to make information on existing

models available to potential users were suggested

at the OTA workshops: 1 ) catalogs, 2) newsletters,

and 3) model clearinghouses.

Catalogs

Various Government agencies and research organizations have published catalogs of available models. Such attempts to distribute model information

have had mixed success. In the rapidly advancing

field of modeling, many catalogs quickly become

outdated, since new models are regularly introduced and old models must continually be updated

to remain current. Consequently, the maintenance

and updating of a usable catalog must be performed

on a continuing basis by a staff with relatively high

levels of expertise.

A number of Federal organizations have included

model-related information in catalogs dealing with

water resources—most importantly, the Selected

Water Resources Abstracts and the Water Resources

Research in Progress File Catalog of the Water

Resources Scientific Information Center. and various publications of the National Technical Information Service. However, these services are not

designed to rapidly access modeling information,

and are too far removed from developers to be extensively used or adequately maintained.

In addition, the Federal Software Exchange Center (FSEC) publishes catalogs of computer programs that Federal agencies consider to be usable

by other Federal, State, and local government agencies. However, the catalogs are not intended to provide comprehensive coverage of even federally developed models, and provide relatively scanty information regarding the models that have been included, Moreover, FSEC regulations prohibit disclosure of the identity of the developing agenc y

without its prior consent, frequently precluding further inquiries by and assistance to potential users.

An extensive discussion of the functions of these

organizations that relate to modeling is provided

in chapter 4 of this report.
50 . Use of Models for Water Resources Management, Planning, and policy

Newsletters

Newsletters are a useful vehicle for disseminating

information about available models. An organization can publish newsletters relatively inexpensively

as a service to current and potential users of its

models. Newsletter services for the Environmental Protection Agency’s (EPA) Stormwater Management Model (SWMM) Users’s Group and the

EPA Center for Water Quality Modeling are described in chapter 4 of this report.

Model Clearinghouses

Clearinghouses offer a comprehensive approach

for disseminating information about models

available from a broad range of participating agencies and organizations. Model clearinghouses serve

as a central resource for obtaining information

about available models, and help to address such

modeling problems as duplication of model development efforts, and improper selection of models.

A clearinghouse’s primary function is to collect

models and model-related information, and disseminate these models and information to the user community. The majority of persons contacted for this

study indicated a strong need for a model clearinghouse. One established clearinghouse for ground

water models at the Holcomb Research Institute

is discussed in chapter 4 of this report.

Of those surveyed by OTA, most who favored

the model clearinghouse concept felt that the clearinghouse’s primary or central role should be to inventory existing models. This inventory might consist of a central catalog of models by subject area,

a list of available models, a list of agencies that use

models, and a notation of a contact person or agency for further information about each model. For

Federal agencies, an inventory would help avoid

duplication of existing models and could improve

interagency coordination of modeling efforts. For

State agencies, an inventory would serve as a source

of information on available state-of-the-art modeling tools.

To meet model users’ needs, the clearinghouse

could also establish a catalog of model characteristics to help users compare the advantages and disadvantages of different models. Users seeking informat ion on a particular model, or on models for a

specific problem, would submit information on the

nature of the pertinent water resource problem and

on any other requirements that influence the choice

of a model—such as cost, level of complexity, assumptions of the model, etc. In turn, trained clearinghouse staff could quickly locate models that generally fulfill these requirements.

Clearinghouses can provide assistance in other

areas as well. State survey respondents indicated

a need for information on sources of technical assistance, training, and data, as well as information on

existing models. Some respondents suggested that

clearinghouses serve as technical assistance and

training centers. Clearinghouses could also have

evaluative functions—developing standards for assessing the materials submitted, and providing technical help in evaluating the utility of available

choices.

It is unlikely that a clearinghouse could initially

be self-financing. Seed money would invariably be

needed to get it started, and outside funding might

be needed throughout its existence. Clearinghouses

could be partially funded by private business or

Federal agencies, and earn the remaining necessary

operating funds by charging for their services.

Another option is for the clearinghouse to conduct

and charge tuition for training courses, which would

publicize the organization as well as generate

income.

Training

User training is among the most effective means

for improving the use of water resource models.

Both model developers and model users who were

contacted during the OTA study consider training

an important aspect of model support. At the present time, neither governmental water resource

agencies nor the private sector are providing the

necessary training for applying models to the decisionmaking process. In response to an OTA survey,

State-level water resource professionals ranked federally sponsored training a priority second only to

data needs, and indicated a need for training assistance in all phases of modeling activities.

Several mechanisms can be employed for training model users and decisionmakers. Individuals

surveyed for this study generally agreed that one-
Ch. 3—Genera/ Issues in Model Development, User and Disssemjnatjon . 51

Photo credit: Ted Spiege/, 1982

A senior hydrologist at USGS headquarters in Reston, Va., demonstrates steps in modeiing river currents. A tape

from the underwater monitoring equipment pictured in left foreground provides data as input to the model, which

is run on the computer terminal above. A portion of the model converts numerical information

into charts and maps of current patterns in the river itself.

to-one interaction between developer and user is

the most successful training approach; however, it

was also identified as the most expensive training

method. Hands-on workshops, which allow users

to run models on computers under supervision,

were identified as the next best method. Traditional

seminar approaches were the third choice for user

training.

A number of Federal agencies conduct user training programs. The U.S. Geological Survey conducts numerous courses in many aspects of modeling, while the Army Corps of Engineers’ Hydrologic Engineering Center (HEC) provides extensive training courses in the use of its major models.

The Instream Flow Group (IFG) at the Department

of the Interior specializes in training both managers

and technicians in instream flow analysis, problem

solving, and related model use. Federal training efforts are described in detail in chapter 4 of this

report. Some agencies are using videotapes of training sessions as less expensive teaching tools. other

innovative techniques may be applicable to train- - .

ing model users, including programed

and self-instruction methods.

User Assistance

Documentation, training, and other

teaching aids

user aids can

go a long way in preparing the decisionmaker for

using water resource models. However, direct assistance by experienced modelers and computer

programmers will often be needed. Sometimes the

problem can be solved simply by a phone call; at

other times, direct contact with a modeler or programer who is familiar with the model may be

needed.

User assistance may range from merely providing information on the status of a new model,
52 . Use of Models for Water Resources Management, Planning, and policy —.— . — ——— ——— ————. ———————— -— -—— —

to advising on model application or preparing input data and analyzing results. User assistance also

helps the modeler to better understand the problems

of applying models by interacting with the decisionmaker-user. Complex models may even require

‘‘tutored application ‘‘ in which modeling specialists

and users work together in applying the model to

the user’s problem. Federal agency user support

groups that have devised procedures for assisting

users include the SWMM User’s Group, HEC,

and IFG. Their experiences in this area are described in chapter 4 of this report.

Maintenance and Improvement

of Models

The development and improvement of models

seldom stops at evaluation and fine-tuning for realworld applications. Models are constantly modified

and improved based on users’ experience, new information, or new methodologies and techniques.

Each change in a model must be documented, and

the users notified of the modification and adjustments in operating procedures that it requires.

It is important that the institutions that sponsor

and support model development make provisions

for updating and maintaining models after they

become operational. Unfortunately, history has

shown that few institutions, whether Government

agencies or academic institutions, provide for the

contingencies of model updating and maintenance.

Clearinghouses or central repositories can play an

important role in ensuring that models are updated

and improved. OTA workshop participants suggested assigning ‘ ‘lead agency’ responsibility to a

Federal Government entity for systematically tracking Government-wide model development and upkeep.

Modeling support groups such as HEC are effective means for assessing model deficiencies, maintaining and improving a model, and notifying users

of subsequent changes in a model.

Additional Model Characteristics

Affecting Ease of Model Use

In addition to the technical assessment of a model’s capabilities and the qualitative evaluation of

its credibility through operational testing (described

in the following section, Issues in the Development and

Use of Models), there are other factors that affect the

value of models as aids to decisionmakers. These

incude:

1.

2.

3.

computational efficiency-is the model Cost

effective in terms of computer use;

ease of use—is the model understandable and

easily operable by users; and

transportability-is the model designed for use

on a range of different computers?

Computational Efficiency

Computational efficiency pertains to computer

costs associated with operating a model. It is generally achieved by carefully designing the model to

make the best use of the capabilities of a particular

computer and by applying state-of-the-art procedures for manipulating and solving equations within the model itself.

Ease of Use

The ease with which a model can be used depends on the design of its input and output characteristics. The input characteristics of a good

‘ ‘user-oriented’ model, i.e. , a model that is designed for use by persons other than the modeler,

ensures that information and data needed for running the model can be introduced into the model

with the least effort and with minimum chances for

errors. Such a model checks the data for completeness and reasonableness, and transforms it into

usable form for processing. The output of a good

user-oriented model can be adjusted to provide the

level of detail and organization of information that

best suits the user. If a computer run cannot be

completed due to errors or incompatibility of data,

an effective model will provide an analysis of the

problem encountered (diagnostic information), and

will warn when computer-generated information

exceeds predetermined bounds.

Transportabilit y

Model transportability is the ease with which

models can be transferred from one computer system to another. Characteristics of computer systems

vary substantially among manufacturers. A model

designed to take full advantage of the various features of a particular computer system, e.g., for stor-
Ch. 3—General Issues in Model Development, Use, and Dissemination ● 53 — — . -

ing information or solving equations, may need

major revisions for use on another computer system. Costs associated with restructuring and

retesting models can be substantial. If a model is

intended for use on a number of different computer

systems, the modeler must avoid using systemdependent features of any particular computer

system. However, designing a transportable model

often results in sacrifices of computational efficiency

and ease of use.

Designing for transportability requires knowledge of the characteristics of a variety of computer

systems. Such knowledge is difficult to acquire and

is not widespread among model developers, since

it must be gained through operating experience on

a range of computer systems.

ISSUES IN THE DEVELOPMENT AND USE OF MODELS

The model development process begins when a

decisionmaker, scientist, or manager identifies an

information need that can best be met through some

form of mathematical analysis. A team of professionals subsequently analyzes the issue and gathers

data on it, develops the mathematical equations that

comprise the model, fine-tunes the model to specific conditions, evaluates model results, and presents

the model-generated information to the individual

requesting it. Oversight from the supporting organization must be provided to assure that model

development proceeds effectively, and that model

results are appropriately used. This section assesses

four major aspects of the process of developing and

using mathematical models:

●

●

●

●

interaction between modelers and decisionmakers;

evaluating models for use by water resource

managers;

mechanisms for assuring adequate oversight

of model development; and

legal aspects of model use in administrative

processes.

Interaction Between Modelers

and Decision makers

The goal of the modeling process is normally to

provide results that are usable in decisionmaking

processes—including day-to-day operations and

management, medium- and long-range planning,

regulator y purposes, and policymaking. To effectively aid decisionmaking, models must provide information that is relevant to the decision alternatives

at hand. In addition, model results must be considered reliable by those responsible for making decisions.

Because modeling is a relatively new field, few

decisionmakers have had an opportunity to use

models as part of their formal education, or to participate in model development processes. While this

trend is changing as a new generation of water resource managers assumes positions of responsibility, lack of familiarity with models and modeling

concepts remains a key impediment to increased

reliance on model-based information. Individuals

contacted or surveyed by OTA repeatedly stated

that models are not used in many water resource

areas because ‘ ‘they are not trusted’ by those

responsible for management and decisionmaking.

Conversely, models tend to enjoy high levels of

credibility among users and decisionmakers who

are familiar with modeling techniques and with the

results of specific models.

Managers who are inexperienced in the use of

these techniques tend to base their judgments about

the value of models on the experience of others. Dr.

William Johnson of HEC observed that ‘ ‘the cllterion of trustworthiness is determined by an acceptable record of use (preferably by those other

than the model developer). Results of OTA

surveys and workshops on modeling* suggest that

the use of models in water resources management

can be broadened by a concerted effort to familiarize resource managers and decisionmakers with the

development and operation of mathematical models.
54 ● Use of Models for Water Resources Management, Planning, and Policy

When a decisionmaker initiates a model development effort, the value of the information he ultimately receives depends directly on his ability to

specify what he needs to know. Yet many professionals routinely state their information objectives

in qualitative terms, and their conception of the

problem to be solved may not lend itself to quantification. Decisionmakers may also look to the model

to explain the issue, when in fact a clear specification of the issue is a prerequisite to developing models of it.

A modeler who is confronted with an imprecise

request for information will normally attempt to

provide the kind of results that he or she considers

critical to the decision—often without success. Modelers usually have a technical or scientific background that is significantly different from that of

the decisionmaker, although there are some exceptions. Without inputs from decisionmakers, modelers may tend to concentrate on ‘ ‘technically correct’ solutions without regard to political considerations that may affect the outcome of a decision.

Photo credts: @ Ted Spiegel, 19S2

Evidence that PCB levels in the Hudson River had the potential to interfere with commercial shad fishing led the New

York State Hudson River Valley Commission to develop models to analyze the problem
Ch. 3—General Issues in Model Development, Use, and Dissemination ● 55

Modelers may also have professional motivations

that lead them to concentrate on developing modeling techniques and mathematical sophistications for

the primary purpose of advancing the state of the

modeling art. Rewards are frequently given on the

basis of professional contribution to the field of

modeling rather than for developing models that

have utility for the decisionmakers. A 1975 survey

of model development project directors conducted

by Fromm, Hamilton, and Hamilton,3 found that

the two most frequently identified benefits of modeling were: 1) ‘ ‘educated the model builders’ (78 percent); and 2) ‘‘pointed a way for further research’

(76 percent). ‘‘ Helped in making policy choices’

ranked only fifth (58 percent). The modeler’s preoccupation with advancing the state of the art of

modeling, while highly useful for anticipating future

needs and identifying critical emerging issues, often

leads in the short run to overly complicated models

that require more information and data for their

use than is practically available to the user/decisionmaker.

Finally, unless the modeler thoroughly instructs

the decisionmaker on how to interpret model results, the information provided may inadvertently

be misleading. By constructing the model, a modeler normally gains an appreciation of its capabilities and limitations—in particular the range of

error associated with various model results. If the

decisionmaker is merely presented with a set of figures and projections, he or she may tend to overrely

on the model accuracy or misinterpret the meaning of the information produced. Such overreliance

may result in a misdirected decision, and cause the

decisionmaker to avoid the use of models in the

future.

The most effective way to avoid these pitfalls in

model development and use is to ensure that modelers and decisionmakers interact and communicate

with each other throughout the model development

process. The institutional setting should encourage

multidisciplinary approaches to problem solving,

involving scientists, modelers, model users, and

manager-decisionmakers. The success of the modeling effort will often depend on stimulating and

maintaining communications among these groups.

3Fromm, Hamilton, and Hamilton, op. cit., p 66

The modeler-decisionmaker team needs to ensure that four questions are continually addressed

during model development or use:

●

●

●

●

Are we developing or using the model to

answer the proper questions?

Is the model capable of producing sufficiently accurate answers?

Will the model be an improvement over existing techniques?

Will the improvement in results justify model

costs?

Neither model developers nor decisionmakers

can answer these questions in isolation from each

other. But bringing the expertise of each group to

bear jointly on model development and use is in

itself a complex undertaking. Creating appropriate

incentive structures in institutions where modeling

activities take place can have a major influence on

how well the interested parties work together to produce appropriately designed models. The professional climate established by top policymakers plays

an important role in encouraging the use of models,

training decisionmakers to use models effectively,

and stimulating the development of usable modeling tools.

Evaluating Models for Use

by Water Resource Managers

Once developed, models must be evaluated to

ensure that the information they generate adequately covers the range of conditions that the decision

objectives demand. This requires not only an assessment of the technical capabilities and limitations

of the model, but also qualitative judgments concerning the nature and extent of the information

needed for the decision at hand.

The evaluation process aims to answer three

questions concerning the model:

● How well does the model’s structure correspond to the structure of events in the real

world? Since models are simplified mathematical representations of real, complex relationships, we need to know how adequately such

simplifications reflect the essentials of these

real-world relationships. Are the model’s assumptions about real-world behavior reasonable? Does the model take account of the fac-
56 Use of Models for Water Resources Management, Planning, and Policy

tors that actually characterize and control the

real-world phenomenon? Is the model sensitive

to changes in those factors that could affect the

real-world response?

How accurately does the model predict events

in the real world? What is the degree of possible error gaged by some measure of performance?

Does the model provide the degree of accuracy

and flexibility required by the user? Is information provided at an appropriate level of detail?

The first question is conceptually the most difficult, and requires both technical and qualitative

analysis of any given model. The second is quantifi-

+

h

‘i -*46P%

Photo credit: @ Ted Spiegel, 1!?s2

Researchers take ice core samples to measure PCB

deposits at Thompson Island Dam, Ft. Edwards, N.Y.

Often, data-gathering must be closely coordinated with

modeling activities if models are to provide information

relevant to the problem at hand. Models can also be used

to help pinpoint those aspects of the problem for which

additional data collection is required

able and can be addressed by a procedure called

‘ ‘validation. The third addresses the relevance of

the information provided, and involves subjective

analysis of the nature of the problem being studied. Modelers and decisionmakers must understand

the outcomes of all three kinds of questions if they

are to evaluate the models they use and the information that models provide them. The following

discussion outlines the major techniques used to

provide these answers.

Technical Assessment of Models

Three technical procedures collectively determine

the accuracy of a mathematical model: 1) verification—assuring that the computer program actually performs as designed; 2) calibration-developing

values for the constants and coefficients in the computer program from field data, in order to accurately predict real-world events; and 3) validation-assessing the model’s accuracy in predicting realworld events.

Verification. —A model is said to be verified when

it is determined that the designer’s conception of

the model is accurately embodied in the program

written and run on the computer. Such a procedure

is applicable to any model, and involves technical

checks to ensure that:

● the written program accurately describes

model’s design;

● the program is accurately mechanized on

computer; and

the

the

● the mechanized program runs as expected.

Verification of a computer model may require

considerable effort to ‘‘debug’ (adjust the program

so that it runs properly), particularly if the model

is large and complex. Although the process of verification is straightforward, and to a large extent

mechanical, the expense and time delays to debug

a program can be significant.

Calibration. —Models must be “fitted’ or ‘‘finetuned’ to the specific characteristics of the realworld system being studied. Each model contains

a set of parameters, i.e., values of coefficients,

that establish the relationship between the model’s

predictions and the information supplied to the

computer for analysis. A model is considered to be

calibrated when model results match experimen-
Ch. 3—General Issues in Model Development, Use, and Dissemination ● 57

tal observations taken from the particular system

under investigation. Calibration is, thus, the procedure used to determine a specific mathematical value for the parameters of a model.

Calibration depends on a reliable set of data collected under conditions as similar as practical to

those prevailing at the time of the decision. Often,

however, data are not available, and the modeler

must depend on assumed values or average values

observed previously for estimates of the parameters.

The use of assumed or hypothetical values often

reduces the reliability of the model.

Validation. —Validation is the process of determining how accurately the model can predict realworld events under conditions different from those

on which the model is developed and calibrated.

To validate a model, a different set of field data

is used as input to the model and the output is compared to actual observations of the new field conditions. Where possible, validation uses a completely new set of data, gathered at a different time or

place than those data used to develop and calibrate

the model. However, in instances of limited data,

a single data set may be split, and the two halves

be used for calibration and validation respectively.

The simplest validation measure is a graphic

comparison of observed data and computed values.

It allows the analyst to make qualitative judgments

about the adequacy of the model and its suitability for additional use, and provides a clearly visible, easily understood assessment of model results.

An example of simple graphic comparison is present in figure 6. More complex models may require

statistical indicators of accuracy to supplement or

supplant graphic presentation. Simple statistical

measures comparing observed and computed values

include correlation coefficients, computation of

relative error, and comparison of means.

Validation depends on a reliable standard for

comparison. The lack of comparative data often

Figure 6.–Comparison of Measured and Computed Runoff for the storm of Aug. 2, 1963–

Oakdale Avenue Catchment—EPA Stormwater Management Model

The graph above compares measured runoff to SWMM estimates of runoff for a single storm event at an individual stormwater

catchment. Amounts of precipitation falling during the course of the storm are shown at the top, and are calculated by the scale

at the right; actual and estimated discharge to the catchment is shown by the lower lines, and is measured by the scale at the left.

SOURCE EPA Stormwater Management Model,
58 . Use of Models for Water Resources Management, Planning, and policy

precludes adequate validation. If a model describes

a unique system or event, then comparisons with

data from other systems (or times) may be impossible. Some models, e.g., models of physical processes

which are governed by law of physics and engineering, are often adaptable for a wide range of applications. Such models can be validated from timeseries observations at a single location—comparing

results with prior historical data—or in combination with similar data from other locations.

Social and economic behavioral models, however, are difficult to validate in the strict sense.

Human behavior cannot be analyzed in the same

sense as interactions that take place in the physical

sciences. Human interactions may be extremely

complex, and involve many factors not readily subject to quantification. At best, social scientists can

estimate statistical variations in human behaviors

under a set of assumed conditions—yet there is no

way to gage the likelihood that the assumed conditions will come to pass. This difficulty is compounded by the necessity to forecast changes in a

number of highly uncertain economic and social

variables, e.g., inflation, commodity prices, and

demographic and employment patterns. Moreover,

the complex interactions of the economic and social

systems are dynamic, i.e., the nature of the system

itself continues to change, thus requiring constant

changes in the model. Under circumstances of

changing system structure, it is nearly impossible

to use long-term time-series data for validating

models.

Qualitative Assessment of Models

Socioeconomic and integrated models are used

by decisionmakers to predict the likely economic

and social effects of policy decisions. As explained

above, such models cannot be validated in the technical sense because there are no statistical means

for assessing the accuracy of the model’s predictions until the predictions have come to pass—or

failed to do so. Moreover, the presence of factors

that have influenced the outcome but have not been

included in the model may preclude any statistical

check on the model’s accuracy. One must therefore

rely on qualitative indicators of the model’s credibility and reasonableness to assess its usefulness

and reliability. Properly understood, such procedures permit policymakers to determine whether

a model’s predictions are sufficiently reliable to

serve as an input to decision processes.

Three techniques can be used to assess complex

predictive models in a qualitative or semiquantitative manner: 1) parts of a complex model can

sometimes be validated independently of the remainder of the model, using historical data to test

the accuracy of the projections; 2) professional consensus can be obtained among experts who review

the reasonableness of the model’s parameters and

structure; and 3) users can perform sensitivity analyses, i.e., comparing the changes in model output

that result when the model is run successively with

small changes in model assumptions. Sensitivity

analysis places less emphasis on the absolute accuracy of projections, and more on the differences that

result from incremental changes in policy, for example.

The decisionmaker must be a major participant

in the qualitative assessment of a model. In the absence of statistical and objective measures of performance, one must rely on the intuition and experience of the decisionmaker in judging the quality

of the information the model supplies and in weighing that against the informational needs for decisionmaking. Similarly, the user/decisionmaker

must be the final arbiter in evaluating the sensitivity

of the model to changing inputs and conditions.

Assessing the Relevance of the Model

A major reason for expending the time, effort,

and funds necessary for using a model is to provide information that is not available from other

sources. A model’s utility to the decision process

depends both on its ability to analyze information

and on the relevance of the information to the decisions to be made. Thus, in the find analysis, the

decisionmaker must gage the usefulness of the model against the profile of the decision itself.

In some instances, a model’s primary use may

be to identify further information that may be

needed to approach the decision; thus the evaluation of the model proceeds as an integral part of

the issue analysis. The term forum analysis is

sometimes used to indicate a procedure in which

a number of models are analyzed to determine their

relevance to a given issue. The forum analysis begins as a comparative exercise, in which different
Ch. 3—General Issues in Model Development, Use, and Dissemination ● 59

Photo credit: @ Ted Spiegel, 19S2

Decisionmakers must understand the assumptions

underlying model-generated information to use it in

deciding policy questions

models are run with the same data set in order to

determine the fundamental differences in their procedures and results. The information generated is

then used as a focal point for examining the issue

itself, as participants attempt to specify the factors

that influence the situation in the real world, and

to improve the model’s capacities to reflect those

factors. The “forum’ for carrying out this assessment simultaneously involves modelers, model analysts, and policymakers. Forum analysis can be a

powerful tool to advance the state of the art of modeling for a specific problem area, and can also contribute to a better understanding of the problem

by providing an analytical framework for considering the issues.

A recent World Meteorological Organization

forum analysis project compared 10 hydrological

models that provide short-term forecasts of

streamflow. 4 The project used data sets from six

rivers with different physical and climatological

characteristics to determine the models’ relative advantages and disadvantages for assessing streamflows in a variety of river types, and under differing institutional constraints and accuracy requirements. The exercise allowed participants in a technical conference to compare the performance of the

tested models, and to develop guidelines for model

selection based on such criteria as the purpose of

the forecast, the prevailing climate within the river

basin, and the quality and type of data and computers available.

Mechanisms for Assuring Adequate

Oversight of Model Development

Although there is broad agreement among the

modeling community that additional measures

are needed to standardize and improve the quality

of models, there is significant disagreement among

modelers as to how this should be achieved. Among

the means of ensuring quality control of models are:

guidelines, standards, contractual agreements, and

peer review. Each of these could potentially limit

the individual modeler’s flexibility and freedom to

approach problems, hence any proposal to create

standards and impose uniformity is a contentious

Issue.

Guidelines and Standards

Proponents of establishing Government-wide

guidelines for model evaluation consider guidelines

an effective means of standardizing and ensuring

compatibility among model development efforts,

as well as a way to screen bad models while enhancing the acceptance of good ones. Such guidelines

could promote uniformity in evaluation criteria,

and contribute to achieving compatibility among

model results.

Opponents point out, however, that the wide variety of user needs may preclude the use of uniform

guidelines. Since a model needs primarily to match

4“Intercomparison of Conceptual Models Used in Operational Hydrological Forecasting, “ World Meteorological Organization, WMO

No. 429, Geneva, Switzerland, 1975.
60 Use of Models for Water Resources Management, Planning, and Policy

the informational needs of an individual user, the

user is in the best position to determine appropriate

standards. Guidelines written to deal with a range

of models would likely be either too vague to be

potentially useful, or limited in applicability to a

few specific models. In either case, guidelines could

inhibit innovative modeling efforts which depart

from accepted practice. This could inhibit advances

in the state of the art in modeling research.

A further difficulty arises in the use of guidelines

within an organizational framework. Procedures intended as general suggestions to guide model

development and use may tend in practice to be

used as standards governing modeling activities. A

manager’s natural desire to minimize risk and preclude responsibility for failure could place pressure

on users and developers alike to follow accepted,

conventional procedures. In the rapidly advancing

field of modeling, such a bias could conflict strongly

with the objective of incorporating the best available

knowledge into current modeling activities.

A General Accounting Office (GAO) report5 supports the guideline concept, while acknowledging

that variations in model development efforts require that guidelines be highly flexible. GAO’s

survey of model developers in the Northwestern

United States revealed skepticism about guidelines—both in general, and in reference to specific

GAO proposals:

A primary concern was the fear that the guidance factors could become requirements for all

modeling efforts. Respondents noted that model

development efforts are not all the same. They differ in size, complexity, and level of the technology

being applied. In addition, the contractual process

as well as the contractual management relationship will vary from project to project. Respondents

pointed to these structural and management differences as evidence of the need for flexibility in

implementing any set of guidance factors. More

specifically they noted the need to allow the manager freedom in determining which factors to consider and the level of activity required.

Survey responses prompted GAO to qualify its

proposals for modeling guidelines:

The guidance factors are not intended as absolute requirements. Rather, they represent a preliminary listing of procedures a manager should

consider when undertaking a model development

effort. These techniques are meant to provide the

manager with an awareness of the total development process—not necessarily to establish a checklist for compliance. Most of the people we talked

to stated that such guidance would be useful if it

remained flexible.

Standards developed for use by a single organization are less likely to encounter objections. For example, the Corps of Engineers has established

guidelines for models that are incorporated in the

Corps’ Engineering Computer Programs Library. b

The stated objectives of the guidelines are to assure

that models distributed through the library are:

1) immediately usable, broad in scope, easy to

modify; 2) consistent with accepted engineering

principles and practices; 3) uniformly and well

documented; and 4) readily understandable by

others and easy to set up and apply.

The standards specify the programing language

to be used, and suggest specific programing practices that will enhance program usability. Detailed

guidelines are provided for preparation of model

documentation. Models that are incorporated in the

library are placed in one of three categories, depending on the nature of the model and the level

of review it has received. For example, a model in

the highest category will have been designed for

Corps-wide application, and will have received independent review and approval by the Corps’ Office of the Chief of Engineers. A further discussion

of Corps’ procedures for developing and disseminating water resource models is included in the

description of HEC in chapter 4.

Contractual Mechanisms

Numerous proposals have emerged for strengthening quality control by requiring the performance

of certain procedures or the attainment of performance standards as part of the legal contract for developing a model. For example, developers might be

5 Wa} ! to Improw ,Management OJ b’edera[~ h’unded Computerized Model~,

LT s (;{)vernnlc.nt A(c ounting {)ffi( (,, 1.C;L)-75- 111, 1976.

6B. Eichert, ‘ ‘Experiences of the Hydrologic Engineering Center

in Maintaining Widely Used Hydrologic and Water Resource Computer Models, Technical Paper No. 56, Hydrologic Engineering Center, 1978.
Ch. 3—General Issues in Model Development, Use, and Dissemination ● 61

— . — —

required to provide specific levels of documentation acceptable to a review panel, or to achieve a

specific level of accuracy before final payment on

their contracts.

Another GAO proposal called for Federal agency review of contractor performance at the end of

each of five phases in developing models. Both the

agency and the developer would have an opportunity to terminate the development process at the

end of each phase:

A contract with a breakpoint at the end of each

phase should be used so that a developer cannot

proceed from one phase to the next without written approval from the user. Each phase or breakpoint should be separately priced so that a termination at the end of a specific phase will limit the

Government’s liability under the contract to those

costs incurred for the contractor’s performance up

to the breakpoint . . . . This gives the manager the

opportunity to stop development if the model is

not going to be useful.

Such procedures could increase an organization’s

control over ongoing model development projects,

and, if properly managed, could offer incentives

for developers to maintain professional standards

and provide adequate user-oriented services. However, additional contractual specifications inevitably

add to the complexity of monitoring model development.

Peer Review

Peer review procedures have been proposed as

a means of identifying and promoting high-quality

models without losing the flexibility required for

innovative modeling. Review panels, composed of

high-caliber professionals who are sensitive to the

applications for which individual models are designed, could provide valuable advice to model developers, and assure sponsoring institutions of the

value of the models they fund.

Opponents of the peer review approach cite the

bureaucratic burden of establishing and maintaining review policies and procedures, and they question the relative value of the additional information as compared to its probable cost. These opponents also point out that seasoned modeling professionals are in relatively short supply—obtaining

their services for a review panel on a continuing

basis might be impossible. The use of less qualified

reviewers for such a panel would reduce the weight

and value of its recommendations.

Legal Aspects of Model Use in

Administrative Processes

Models are often used to project the effect of a

proposed administrative action, Managers employ

model forecasts to minimize the possibility of causing costly errors or potential damages associated

with inappropriate decisions. Major decisions involving millions of dollars may be based on modelgenerated information. If, for some reason, the

models do not accurately simulate real conditions,

administrative decisions based on model results

could misdirect regulations, misguide management

directives, and misallocate capital investments.

Using models in regulatory processes raises the

prospect that unforeseen errors may cause administrative actions to either fall short of their intended

purpose or unreasonably burden those who are reg

-

ulated.

Legal issues regarding the use of models in administrative processes have arisen in three areas:

1) standards for Federal judicial review; 2) judicial

review of State-level regulations; and 3) use of models for planning and program development.

Standards for Federal Judicial Review

Although judicial consideration of water resource

models dates back to a 1943 Supreme Court case

involving an interstate dispute over water rights, 7

virtually all judicial notice has been in the context

of recently promulgated water quality effluent limitations. a Courts have also examined water quality

models that have been used as the basis for analyzing an environmental impact statement under the

National Environmental Protection Act. g

‘Colorado v. Kansas, 320 U S. 383 ( 1943)

8Assoctatton ojPacJic Ftshenes ~’. E P A , 61.5 F 2d 794 (9th C ir , 1980);

Kennecott Copper V. E. P A 612 F.2d 1232 (10 Cir. , 1979); I?AS’F Wyan- {

dotte Corp v. Cost[e, 598 F 2d 637 (1st Cir, , 1979); ,Vatzonal Crushed

Stone Association v. E P A 601 F.2d 111 (4th Cir., 1979); American Zron

and .Steef Instttute v, E P A ( 1 1), 568 F 2d 284 (3rd Cir, , 1977); FMC

t. 7’razn, 539 h’, 2d 973(4th L’ir. , 1976); API V, L’ P A , 540 F’. 2d 1023

(lO{h Cir., 1976); A I S 1 \ EPA (1~, 568 F,2ci 284 (3r(i Ctr., 1977),

‘ohlo Ex t?d Ilrouw L. E P A , 460 F, Supp. 248 (S L) oh,, 1978);

Con~erLatton Counctl oj ,Yrorth Carollna ,, Froehlke, 435 F Supp, 77 5

(M D N C , 1977),
62 Use of Models for Water Resources Management, Planning, and Policy

Models used for agency rulemaking are administrative actions reviewable by the courts. 10 The

review standard is narrow:

As in other cases involving review of an administrative agency’s rulemaking actions we are

governed by an ‘‘abuse of discretion’ standard—

in other words, we must not substitute our judgment for that of the agency, but must determine

whether the administrator’s actions were ‘ ‘arbitrary, capricious, are abuses of discretion, or

otherwise not in accordance with law . . . .‘ In

order to facilitate meaningful judicial review, we

should require administrative agencies to ‘ ‘articulate the standards and principles that govern

their discretionary decisions in as much detail as

possible . . . . “11

Most courts reviewing models as a basis for administrative decisions rely on the standard set out

in the U.S. Supreme Court case, Citizens to Preserve

Overton Park v. Volpe, 12 that a court reviewing an

agency’s action should conduct a searching and

careful inquiry into the facts, but should not

substitute its judgment for that of the agency. The

court held that the agency’s use of the model should

be accorded a ‘ ‘presumption of regularity. “13

This judicial standard has significant implications

for an agency’s use of models in regulation, and

grants broad discretion to the agency. When other

models have been used to challenge an agency’s

model, the courts have examined only whether the

agency’s model constitutes a ‘‘rational choice. 14

Although judicial inquiry will include a thorough

evaluation of a model, it does not extend to the

determination of the “best possible approach. ’15

l’JThe Feder~ Administrative Procedure Act provides that ‘‘except

to the extent that—( 1 ) statutes preclude judicial review; or (2) agency action is committed to agency discretion by law, 5 U. SC. sec.

701 (a) ( 1976), ‘ ‘final agency action for which there is no other adequate remedy in a court (is) subject to judicial review. 5 U. S.C.

sec. 704( 1976). For a discussion, see, D. P, Currie, ‘ ‘Judicial Review Under Federal Potlution Laws, 62 Iowa Law Review 1221 ( 1977).

11A. 1. S. 1. V. E P A. (1), 526 F. 2d 1027 (3d C ir., 1975).

lZC1t1zen5 to prt-sovt ouerton park, Inc v. Volpe, 401 U.S. 402 416

(1971).

Isol,flton Park, 401 U.S. at 415.

14Cleve]and E]ec[r;c I]fuminating CO. V. E. P. A., 5~’2 F.zd 1150,

1161 (6th Cir., 1978), cert. denied, 439 U.S. 910 (1978); U.S. Steel

Corp. v. E. P. A., 605 F.2d 283, 292 (7th Cir., 1979).

1 BCleLle[and Electric, 572 F. 2d at 1150, 116 1; see also, b’ermont Yankee

A’uclear Power Corp v. NRDC, 435 U.S. 519, 549 ( 1977).

However, the documentation of the model must

provide an ‘‘adequate explanation’ of the basis for

the regulation, absent which the court will overturn the regulation. 16 What constitutes ‘‘sufficient

material upon which to make a reasoned decision,

though, leaves a great deal of latitude to an

agency. Thus, there is a disinclination to ‘‘second

guess the agency’s expert determinations as to the

model . . .

Federal courts have proved relatively flexible in

applying the ‘‘reasonable basis’ test to disputed

regulations. In a case where a model simplified the

simulation of complex hydraulic flows in plastic

manufacturing plants to the degree that the range

of flows departed from the model’s results by a factor of 10, the court found no reasonable basis for

the challenged regulation. In another instance,

although the court heard arguments that the challenged model process differed from actual operation by a factor of 5, it sustained the contested

regulation, being convinced that a reasonable explanation for the variation existed.20

The courts’ reluctance to involve themselves in

evaluating models per se is further illustrated by

a case involving proprietary models. In Cleveland

Electric, which challenged the imposition of a sulfur

dioxide control plan based on the use of an EPA

model, the agency’s model was contested as inferior

to a proprietary model developed by an engineering company. Although expert witnesses testified

that a superior method of control existed, the company refused to reveal the operating details of its

model. As the court saw the problem:

While such withholding may be both defensible as a matter of law and understandable as a matter of economics, this court cannot consider Enviroplan’s model as available technology until and

unless it is fully disclosed and evaluated by United

States E.P.A. —the agency charged by Congress

with making these decisions. zz

~6Kmneco~t COO/MT V. E. p. A , 612 F.2d 1232, 1240 (lOth Cir,, 1979).

~~A150ciation oJPul@ Fishmtes v. E. P.A , 615 F. 2d 794, 803 (9th Cir.,

1980).

lapacl~ic Ftsheries, 615 F. 2d at 810.

t9FA~C coTp, v, Train, 539 F, 2d 973, 980 (qth C ir. , 1976).

zopacl~lc F1fhU1e5, 615 F. 2d at 810, 814.

21572 F,2d at 1163.

‘

z Ibid,
Ch. 3—General Issues in Model Development, Use, and Dissemination ● 63

Judicial Review of State-Level Regulations

Relatively few legal controversies have arisen

over use of models by a State government as a basis

for decisionmaking. The lack of reported cases may

be partly attributable to a general lack of model use

by States for regulatory purposes. Another reason

may be the close link between Federal and State

programs —such conflicts may arise in the context

of the applicable Federal programs.

States have occasionally used models as evidence

in administrative proceedings to determine whether

a violation of an environmental control law has occurred; this is particularly true in the area of air

pollution control .23 For instance, the Illinois Pollution Control Board applied a ‘‘general theoretical

formula” to the processing data of a smelting company to find the company in violation of air pollution standards, However, upon review, an Illinois

court held that such modeling evidence was insufficient to support the board’s determination.24

Litigation over regulations predicated on information from a ground water model occurred in the

State of Washington in 1975. The State had developed a computer model for defining maximum rates

of withdrawal and issuing new rights to ground

waters. For the Odessa area, which had been declared a critical ground water region, the State

issued regulations to establish ceilings on withdrawals with the assistance of the developed models. 25

Affected ground water users disputed the accuracy

of the model results;26 however, the courts upheld

the regulation. Subsequent corrections to the model

have altered model results, though not to the degree

of affecting the regulation’s efficacy in the eyes of

State officials. Nonetheless, no further challenges

to the regulation have been offered .27

23 For a discussion, see, R. A. Brazcuer, “Air Pollution Control;

Sufficiency of Evidence of Violatlon in Administrative Proceedings

Terminating in Abatement Orders, ” 48 A L R 3d 795

~~.4[[ted Me[a[ C. v I[[lnou Po[[utton Control Board, 22 I ~ ~ APP. 3d

823,318 N E.2 257, 264 (1974).

Z5G. E, .Maddox, et d., ‘‘,Management of Groundwater in Eastern

1+’ashington, Engineering, Geology, and Soils Symposium, 13th Annual Proceedings, University of Idaho, Moscow, Apr. 2-4, 1975, p.

201, published by Idaho Transportation Department, Division of

Highways, Boise, 1975.

ZbConversation with Alan Wald, Hydrologist, Washington Depmment of Ecology.

*

pConversation with Charles Roe, Senior Assistant Attorney General, Washington Department of Ecology.

Use of Models for Planning

and Program Development

Probably in no other area is the use of models

more prevalent than in planning and program development. However, errors in planning programs

which are based solely on analysis by models can

be perpetuated in decisions made on the basis of

such plans. Mandated ‘‘consistency’ requirements

are potentially a major avenue for institutionalizing this kind of error.

For example, the Clean Water Act requires that

the National Pollution Discharge Elimination

System permits issued for point sources of pollution must not conflict with an approved section 208

areawide management plan.28 In this manner, Congress established a ‘‘consistent’ planning system,

linking different elements to areawide planning

under section 208. Consistency requirements also

extend to construction of publicly owned treatment

facilities, which must conform with the approved

section 208 plan to be accepted.2g Section 208 plans

depend heavily on modeling. This statutory linkage

between the areawide planning programs and regulation or construction activities raises the question of whether unforeseen modeling errors in plans

may cause significant problems during implementation, and subsequently lead to litigation.

An important corollary to this issue is the question of a modeler’s liability for the effects of inaccurate model results. No ruling yet exists on

whether model use involves an express or implied

guarantee that the operation of a system will substantially conform to model-generated information.

If an individual or organization is placed in the position of certifying compliance with regulatory standards based on model results, whose responsibility

is any subsequent nonattainment of such standards?

Absent any definitive ruling on the issue, new

regulatory programs involving modeling and the

use of highly sophisticated modeling analysis may

increase the liability of the design professional. Similar problems have arisen over the professional liabilities of technically trained staff in other fields.

The modeling community has already indicated its

concern over exposure to liability in the context of

Zsclean water Act, sec. 208(e), 33 U. SC. sec. 1288(e).

ZgC]ean Water Act, sec. 208(d), 33 U. S.C. sec. 1288(d).
64 . Use of Models for Water Resources Management, Planning, and Policy

certifying compliance with building energy per- Increased use of complex modeling systems, and

formance standards under the Energy Conserva- layered model use to develop State ‘ ‘equivalent’

tion Standards for New Buildings Act of 1976.30 standards or programs under Federal mandates,

30Milt I.unch, “DOE’s New BEPS Pose Many Legal, Liability may compound initially acceptable modeling errors,

Questions for Design Professionals, ” Engineering Times, April 1980; and also increase a modeler’s potential liability.

Statement of E. K. Riddick for the National Society of Professional

Engineers on the Proposed Building Energy Performance Standards,

Mar. 24, 1980, pp. 14-16.

3 I Testimony of D, carter for the American Consult Ing F.ngineers

Council, hearings before the Senate Governmental Al’fairs Committee, Nov. 20, 1979, p. 167.
Chapter 4

Federal Use and Support

of Water Resource Models
.

Contents

Page

Analysis of Current Federal Modeling Capabilities . . . . . . . . . . . . . . . . . . . . . . 67

Methods Used to Survey and Analyze Federal Model Use. . . . . . . . . . . . . . . . . . . . 67

Findings From the Federal Agency Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Findings From the Federal Workshop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Current Approaches to Federal Model Management . . . . . . . . . . . . . . . . . . . . . 76

Consideration of Models in Governmentwide Water R&D Policies . . . . . . . . . . . . 77

Existing Governmentwide Mechanisms for Coordinating Modeling and

Model-Related Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Existing Support Structures for Agency-Level Modeling Activities . . . . . . . . . . . . . 84

Agency-Level Mechanisms for Providing Information on and Access to

Existing Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

Table No.

3. Federal

4. Agency

Models

TABLES

Page

Model Use by Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Estimates of Fiscal Year 1979 Expenditures for Water Resource

and Related Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Chapter 4

Federal Use and Support

of Water Resource Models

The Federal Government has a very broad range

of water resource responsibilities. It is a major investor in facilities to control water supplies and treat

polluted waters. It has taken the lead in programs

to bring additional supplies to water-short areas of

the country, and more recently to encourage more

cost-effective approaches to water use in these areas.

It has provided the legal and institutional framework within which States work to set water quality standards and ensure that they are met. Moreover, it is responsible for managing the water that

flows through the 776 million acres of the country

directly under Federal jurisdiction.

These responsibilities are expressed in numerous

laws, and are administered by an array of Federal

departments, agencies, and regulatory authorities.

Water resource concerns touch virtually every aspect of the Nation’s economic, social, and political

well-being; thus, they are an integral part of the

missions of many governmental institutions.

In analyzing Federal use of water resource models, the Office of Technology Assessment (OTA)

collected and evaluated information from over 20

agencies and agency offices. Model use was examined by agency, by authorizing legislation, by resource issue, and by professional discipline.

ANALYSIS OF CURRENT FEDERAL

MODELING CAPABILITIES

Methods Used to Survey and

Analyze Federal Model Use

OTA used two primary approaches in soliciting

information on Federal modeling efforts. It initially

held a 2-day workshop for Federal modelers during October 1979, to determine their views on current major problems in Federal water resource

modeling efforts. Attended by representatives from

21 Federal organizations, the workshop revealed

significant institutional constraints to effective

model development and use. In preparation for the

workshops, each agency represented was requested

to provide written responses to questions regarding

its current use and development of models; critical

problem areas, appropriate roles, and reasons for

using models; anticipated future modeling needs;

and current levels of monetary and personnel resources devoted to modeling.

At the workshop, modelers met in groups according to areas of professional expertise. Each group

listed, discussed, and ranked the importance of its

model-related concerns. Major findings from the

workshop are summarized below; a more extensive

summary of the Federal workshop, and of a subsequent workshop held for modelers from universities

and the private sector, is presented in appendix A.

The second major component of OTA’s information-gathering activity was a survey of the 22 Federal entities with substantive water resource responsibilities, conducted in June 1980. Each agency or

office was requested to provide information on its

model use under more than 20 major pieces of

water resource legislation. Respondents were asked

to specify legislatively assigned responsibilities, and

areas in which models are employed, according to

eight general use categories: 1 ) program planning;

2) promulgating regulations; 3) enforcing regulations; 4) complying with regulations; 5) planning

or evaluating projects; 6) allocating funds; 7) technology transfer; and 8) operations and management. Statistical results of this survey are tabulated

in table 3. Detailed descriptions of each agency’s

model use under specific laws and programs are

67
68 . Use of Models for Water Resources Management, Planning, and policy

Table 3.—Federal Model Use by Program

Number of agencies Agencies using

Number of agencies using models to models to meet

with program meet program program

Section involvement responsibilities responsibilities

Federal Water Pollution Control

Act Amendments of 1972 (as

amended by the Clean Water Act

of 1977)

Grants for pollution control

program. . . . . . . . . . . . . . . . . . . . . . .

Mine water pollution control

programs. . . . . . . . . . . . . . . . . . . . . .

Grants for construction of

treatment works. . . . . . . . . . . . . . . .

106

107

201

2

2

5

0

2

4

FS, BM

ESCS, CORPS,

USGS, EPA-OWRS

Areawide waste treatment

management. . . . . . . . . . . . . . . . . . . 208

209

7

9

6

7

EPA-OWRS, BR,

FS, ESCS, SEA

BR, FS, EPA-OWRS,

ESCS, NOAA,

WRC, USGS

EPA-OWE, NOAA

Basin planning. . . . . . . . . . . . . . . . . . .

Water quality waivers. . . . . . . . . . . . .

Water quality-related effluent

limitations. . . . . . . . . . . . . . . . . . . . .

Water quality standards and

implementation plans. . . . . . . . . . .

301

302

303

2

4

6

2

1

4

EPA-OWRS

BR,FS, NOAA,

EPA-SWER

Toxic and pretreatment effluent

standards. . . . . . . . . . . . . . . . . . . . .

Oil and hazardous substances

liability. . . . . . . . . . . . . . . . . . . . . . .

Clean lakes. . . . . . . . . . . . . . . . . . . . . .

Thermal discharges and

exemptions. . . . . . . . . . . . . . . . . . . .

Guidelines and permits for dredged

or fill material. . . . . . . . . . . . . . . . .

Disposal of sewage sludge. . . . . . . .

Safe Drinking Act

Determining adverse health

effects. . . . . . . . . . . . . . . . . . . . . . . .

Protection of underground sources

of drinking water. . . . . . . . . . . . . . .

307

311

314

316

404

405

8

4

6

3

7

7

2

1

3

2

1

1

EPA-OWRS, NOAA

USGS

FS, NOAA, USGS

USGS, EPA-OWE

USGS

ESCS

1412

1421

1

8

1

3

EPA-DW

USGS, MINES,

EPA-DW

Protection of sole-source aquifer

systems. . . . . . . . . . . . . . . . . . . . . . .

Surface impoundment assessment.

State program grants. . . . . . . . . . . . .

Special study and demonstration

project grants. . . . . . . . . . . . . . . . . .

Toxic Substances Control Act

Testing of chemical substances

and mixtures. . . . . . . . . . . . . . . . . .

Regulation of hazardous chemicals

and mixtures. . . . . . . . . . . . . . . . . .

Resource Conservation

and Recovery Act

Solid waste management guidelines

Identification and listing of

hazardous wastes. . . . . . . . . . . . . .

Standards for owners and operators

of hazardous waste treatment,

storage, and disposal facilities. . .

Consolidated permits for hazardous

waste management facilities. . . . .

1424

1442

1443

1444

EPA-DW

EPA-DW

EPA-DW

1

1

1

5

1

1

1

1 USGS

4

6

4

5

1

1

EPA-PTS

EPA-PTS

1008

3001

4

4

1 USGS

0

3004

3005

7

5

0

0
Ch. 4—Federal Use and Support of Water Resource Models 69

Table 3.-Federal Model Use by Program (Continued)

Number of agencies Agencies using

Number of agencies using models to models to meet

with program meet program program

Section involvement responsibilities responsibilities

Grants for State resource recovery

and conservation plans. . . . . . . . .

Full-scale demonstration facilities

grants . . . . . . . . . . . . . . . . . . . . . . . .

Resource recovery system and

improved solid waste. . . . . . . . . . .

Endangered Species Act

Minimizations of impacts of Federal

activities modifying critical

habitats. . . . . . . . . . . . . . . . . . . . . . .

Surface Mining Control and

Reclamation Act

Surface coal mine reclamation

permitting. . . . . . . . . . . . . . . . . . . . .

Permit approval or denial. . . . . . . . . .

Environmental protection

performance standards for

surface coal mine reclamation. . .

Soil and Water Resource

Conservation Act of 1977

Data collection about soil, water,

and related resources. . . . . . . . . . .

Soil and water conservation

programs. . . . . . . . . . . . . . . . . . . . . .

Water Resources Planning Act

Regional or river basin plans and

programs and their relation to

larger requirements. . . . . . . . . . . . .

Coordinating Federal water and

related land resources programs

and policies. . . . . . . . . . . . . . . . . . .

Assessemnt of the Nation’s water

resources conditions. . . . . . . . . . .

Coastal Zone Management Act

State coastal zone land and water

resources management program

development and management

grants. . . . . . . . . . . . . . . . . . . . . . . .

Executive Order 11988

Flood plain management. . . . . . . . . .

Flood Control Act of 1936

and Amendments

Flood control structures. . . . . . . . . .

National Flood Insurance Act of 1968

Identification of flood-prone areas. .

Federal Reclamation Act of 1902

and Amendments

Irrigation distribution systems. . . . .

Construction of small projects. . . . .

National Environmental Policy Act

Administration; EIS review and

comment. . . . . . . . . . . . . . . . . . . . . .

4008 1 0

8004 1 0

8006 3 1 USGS

7 9 3 BR, FS, FWS

506

510

6

1

3

1

FS, USGS, OSM

OSM

515 6 4 FS, USGS, BM, OSM

5

6

6

7

2

5

FS, USGS

FS, ESCS, NOAA

USGS, BM

102 10 7 BM, BR, ESCS,

CORPS, NOAA,

USGS, WRC

102

102

7

1

2

1

USGS, BM

WRC

305

2&3

6

9

2

5

NOAA, USGS

FS, CORPS, USGS,

WRC, NRC

1,2,3, 7 5

2

BR, FS, CORPS,

NOAA, USGS

1360 2 FEMA, SCS

(43U.S.C.421)

(43U.S.C.422)

5

3

3

1

USGS, FS, BR

FWS

102,103 5 5 BR, FS, CORPS,

NOAA, NRC
70 ● use of Mode/s for Water Resources Management, planning, and policy

Table 3.–Federal Model Use by Program (Continued)

Number of agencies Agencies using

Number of agencies using models to models to meet

with program meet program program

Section involvement responsibilities responsibilities

Atomic Energy Acf of 1954

Flood protection of nuclear

facilities. . . . . . . . . . . . . . . . . . . . . . 10 CFR 50 1 1 NRC

Water supply for nuclear power

facilities. . . . . . . . . . . . . . . . . . . . . . . . 10 CFR 50 1 1 NRC

Limitation of radioactive liquid to

ground and surface water. . . . . . . 10 CFR 20, 50, 61 2 2 NRC, USGS

Fish and Wildlife Coordination Act

Consultation and provision of

recommendations; surveys and

investigations. . . . . . . . . . . . . . . . . . 182 2 2 FWS, NOAA

Colorado River Basin Salinity

Control Program. . . . . . . . . . . . . . . 10, 201, 202, 203 2 2 BR, SCS

Agency abbreviation key:

ASCS —

CORPS –

BM –

BR –

DOE –

EPA –

DW –

OWE –

OWRS –

SWER –

PTS —

Agricultural Stabilization and Conservation Service

Army Corps of Engineers

Bureau of Mines

Bureau of Reclamation

Department of Energy

Environmental Protection Agency

Office of Drinking Water

Office of Water Enforcement

Office of Water Regulations and Standards

Solid Waste and Emergency Response Program

Pesticides and Toxic Substances Program

ESCS

FEMA

FS

FWS

NOAA

NRC

OSM

Scs

SEA

USGS

WRC

provided in appendix B. Insofar as OTA has been

able to ascertain, no previous governmentwide

compendium of water resource model use and application has been attempted.

These information-gathering activities were supplemented by OTA-commissioned reports on

model uses, limitations, and appropriate roles in

four broad water resource areas, and by telephone

surveys regarding costs associated with modeling

activities for fiscal year 1979. Estimates of fiscal year

1979 expenditures for water resource models are

provided in table 4. OTA has also relied on previously published studies of Federal, Canadian, and

international model use to corroborate its general

findings. Five of the most relevant studies are summarized in appendix C; individual references to

these findings are also made throughout this

chapter.

Findings From the

Federal Agency Survey

Table 3, which summarizes agency model use

by law, and compares areas of responsibility to

areas in which models are employed, provides a

———————————

Economics and Statistics Cooperative Service

Federal Emergency Management Agency

Forest Service

Fish and Wildlife Service

National Oceanic and Atmospheric Administration

Nuclear Regulatory Commission

Office of Surface Mining Reclamation and Enforcement

Soil Consewation Service

Science and Education Administration

U.S. Geological Survey

Water Resources Council

Table 4.—Agency Estimates of Fiscal Year 1979

Expenditures for Water Resource Models and

Related Activities (in millions of dollars)

U.S. Geological Survey:

Research. . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0–4.0

Application. . . . . . . . . . . . . . . . . . . . . . . . . 12.0—15.0

Army Corps of Engineers. . . . . . . . . . . . . . . 6.5—7.7

National Science Foundation. . . . . . . . . . . . 2.8

National Oceanic and

Atmospheric Administration. . . . . . . . . . . 2.8

Department of Energy. . . . . . . . . . . . . . . . . . 0.9–1 .1

Department of Agriculture. . . . . . . . . . . . . . o.7a

Department of Interior. . . . . . . . . . . . . . . . . . 4.7—5.9

Environmental Protection Agency. . . . . . . . 7.8—9.4

Total. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40.2—49.4

alncludes estimates only from SCS and ESCS.

SOURCE: Developed from information provided in agency responses to OTA

questions regarding model use, October 1979, and from a June 1979

telephone survey of selected Federal agencies. Figures include expenditures for both research and application.

general indication of current patterns of Federal

water resource activities and model use. As might

be expected, the more comprehensive the scope of

a water resource-related law, the greater the number of agencies whose missions are affected by it.

The widest-ranging of current water resource laws,

the Clean Water Act of 1977, involves about 15

agencies and offices, which are assigned various
Ch. 4—Federal Use and Support of Water Resource Models ● 71

responsibilities under or must comply with regulations stemming from 14 different sections of the law.

Twelve agencies or offices indicated model use

under this act. Some laws, such as the National

Flood Insurance Act of 1968 (Public Law 90-448),

are the responsibility of a single agency—in this

case, the Federal Emergency Management Agency. On the whole, however, most pieces of Federal

legislation affect more than a single agency, office,

or regulatory authority.

None of the laws identified in the Federal agency survey specifically require the use of models to

analyze a water resource issue. However, many of

the analytic responsibilities specified in the legislation are routinely carried out with models. Under

the Forest and Rangeland Renewable Resources

Act of 1974 (Public Law 93-378), for example, the

Forest Service of the U.S. Department of Agriculture (USDA) is charged with developing and implementing long-range land and resource management

plans for the federally owned forests under its jurisdiction. It uses models that assess the effects of different management practices on water supply,

water quality, other significant natural resources,

and local economic activity. The information generated by these models is used in determining National Forest Management Act Regulations.

Much of the current Federal legislation directs

individual agencies to determine standards that may
72 . use of Mode/s for Water Resources Management, Planning, and policy

affect the program responsibilities of other agencies. Under the Clean Water Act (Public Law

95-21 7), the Safe Drinking Water Act (Public Law

93-523), and the Toxic Substances Control Act

(Public Law 94-469), the Environmental Protection Agency (EPA) regulates and sets allowable concentrations for a number of toxic substances, organic chemicals, pesticides, and other residuals. A variety of models are used to determine how these substances are transported to and within receiving

waters, and to estimate their effects on human and

aquatic populations. Such regulations must subsequently be incorporated into analyses performed

by various agencies of USDA and the Bureau of

Mines, land and forest management practices of

the Department of the Interior (DOI) and the

Forest Service, and permitting processes of the

Nuclear Regulatory Commission for thermal effluents, among others.

The findings outlined in table 3 reflect a highly

uneven pat tern of Federal model use for water resource analysis. While some agencies use models

to analyze a particular resource issue throughout

the range of their statutorily assigned program

responsibilities, others use them only for a particu

lar responsibility (e.g., complying with regulations),

and still others rely solely on noncomputerized analytical approaches. These inconsistencies cause such

problems as inconsistent flood plain delineations by

different agencies, confusion over best management

practices for controlling nonpoint source pollution,

and disputes over projections of the amount of

water available for energy development in the Western United States. Further, while highly efficient

model-based management techniques have been developed in several Federal agencies (e. g,, for operating reservoirs), many agencies do not benefit from

this already-developed expertise.

A number of factors underlie agency decisions

regarding model use. Developing a model is an expensive and technically complex undertaking, involving highly specialized personnel requirements,

extensive computer facilities, and appropriate data

bases. If the problem to be analyzed is not directly

related to the agency’s mission, the agency will

often be reluctant to commit the resources necessary

to develop a model to address the problem.

Moreover, substantial difficulties often deter

agencies from adapting models that have already

been developed elsewhere in the Federal Government. When practicable, model adaptation permits

significant cost-savings, although adequate data

bases and computer facilities, in addition to technical assistance in adapting the model, are still necessary, However, information about the availability

of many existing Federal models is not readily obtainable. Few agencies have taken steps to disseminate information on the models they have developed. In addition, Federal models are often so poorly documented that a manager cannot determine

their suitability for use by his agency.

Findings From the Federal Workshop

Although Federal agency modelers met and discussed issues in four separate professional groupings—l) surface water flow and supply; 2) surface

water quality; 3) ground water; and 4) economic/

social-the majority of their concerns were not specific to these areas, but encompassed the broader

problem of providing adequate and appropriate institutional support for modeling activities in

general. Indepth summaries of modelers’ deliberations on such issues as research and development

(R&D) needs, data needs, documentation, validation, technology transfer, model maintenance, the

utility of model clearinghouses, and interagency

coordination, are provided in appendix A.

Participants ranked the following issues as being

among the most significant of those discussed:

●

●

●

●

●

●

The

collecting accurate and adequate data to

develop, test, and apply models;

improving decisionmaker understanding 01

general capabilities and limitations of models;

improvements in user support, training in

model use, and analysis of results;

greater emphasis on documentation of models;

improved planning and resources for model

maintenance and management;

making federally developed models known and

available to other Federal agencies and to the

public; and

improving coordination among agencies for

model development and use.

significance of these issues to water resource

analysis and problem-solving capabilities at the Federal level is discussed below.
Ch. 4—Federal Use and Support of Water Resource Models 73

Data Availability

The availability of sufficient data to characterize

a physical system is critical to modeling it successfully. Computer models are often highly data intensive, requiring independent data sets for development, calibration, verification, and application

phases. Workshop participants pointed to the expense of collecting water resource data as a major

limiting factor in constructing models.

Most existing Federal data bases are created to

serve program purposes rather than for research

and analysis per se. Developers consequently find

much of the existing data unsuitable for modeling

activities. Participants suggested coordinated approaches to data collection and model development,

as well as sensitizing model developers to the potential data requirements (and costs) of their models.

Emphasis was also placed on the need to improve

access to existing data bases, and improve the cost

effectiveness of future data collection efforts, particularly through interagency coordination and data

base consolidation.

Coordinating and integrating data collection on

a governmentwide basis is a major Federal management issue, and concerns many informational purposes in addition to modeling efforts. Consequently,

an indepth analysis of Federal data-gathering activities is beyond the scope of this report. However,

results from the OTA workshop and surveys, as

well as surveys of federally developed models by

the National Science Foundation (NSF)l and the

General Accounting Office (GAO),2 indicate that

modelers and managers alike consider problems in

obtaining data to be the most prevalent limitation

on model development efforts. Three of the four

OTA workshop groups considered this to be their

top priority concern, while respondents to the GAO

survey attributed one-fifth of all identified modeling problems to data availability. Any future attempts to improve Federal data-gathering practices

and procedures will have major effects on the modeling community. Input from this community

should be solicited in data collection planning to

‘Gary Fmmm, William L. Hamilton, and Diane E. Hamilton, Federally Supported Mathematical Models Survey and A nalysls, under contract

with the Division of Social Systems and Human Resources of the National Science Foundation, June 1974.

2 Ways to Improue Management oj Federally Funded Computerized Models,

General Accounting Office, August 1976.

minimize additional data-gathering costs associated

with future modeling efforts.

Improving Decisionmaker

Understanding of Models

Information gaps between decisionmakers and

modelers were among the top three priority concerns for all four modeling groups at the OTA Federal workshop. Workshop participants focused on

the relationship between modeling and the decisionmaking process as a major deficiency in current

Federal modeling practices. Upper-level managers

were characterized as being unaware of basic modeling concepts and of the limitations and capabilities

of the specific models they use. Modelers pointed

to a lack of mechanisms throughout the Federal

Government for bringing managers and modelers
74 ● Use of Mode/s for water Resources Management, Planning, and policy

together to plan and develop models. Such a lack

of interaction was seen as a major contributor to

management-level mistrust of models, and the inadequacy of current levels of support for planning

long-range model development, documenting and

maintaining models, and providing user services.

These findings are strongly in accord with those

from earlier studies. The survey of 222 nondefense

Federal models conducted in 1974 for NSF found

highest rates of failure in modeling projects designed

to provide information to policy makers. The low

utilization rate of such models was attributed primarily to lack of communication between model

builders and potential policy makers during model

development, and secondarily to policymakers’ limited understanding of models that had already been

developed. 3 Similarly, one-fifth of modeling problems identified in the GAO survey (1976) were attributed to ‘‘lack of management acceptance and

knowledge of modeling techniques.”4

Integrating the needs of decisionmakers into

model development processes is especially critical

if models are to be used effectively at agency decisionmaking levels. Federal managerial personnel

often have a great deal of discretion over what procedures to employ in analyzing an issue. Some may

have obtained favorable results from modeling in

the past, while others may have been ‘‘burnt’ by

relying on the accuracy of model-based information. Since the Federal Government provides no

guidelines regarding model uses for analytical purposes, and offers very little management-level

education in model use and interpretation, decisionmakers are generally ‘ ‘on their own’ in

deciding when to commit their agencies to modeling efforts.

In practice, Federal agencies tend to commission

models in response to a specific problem, when a

decisionmaker becomes aware of the need for otherwise unavailable information. All too frequently,

however, Federal modelers are given little instruction regarding the nature of the desired information, and are not provided access to the individual(s)

who must act on the information generated. Technically sophisticated, yet impractical models often

3Fromm, Hamilton, and Hamilton, op. cit., pp. 3-7, 51-54

‘General Accounting Office ( 1976), op. cit. , p, 37.

result, and are quickly abandoned to agency archives.

User Support

Participants in the OTA modeling workshop frequently asserted that Federal modeling efforts have

overconcentrated on model development, and devoted inadequate resources to transferring modeling technology and expertise to potential users. All

four workshop groups placed some aspect of user

services among their top three priorities. Many participants stated, however, that current agency career evaluation systems discourage modelers from

providing such technology transfer to model users.

While incentives are provided for developing increasingly sophisticated models, no incentive structure currently encourages modelers to aid users in

understanding, running, and interpreting the results of such tools.

Workshop participants singled out three major

aspects of technology transfer as needing additional

attention and resources: 1 ) documentation; 2) training in model use and interpretation; and 3) technical assistance. Most participants appeared to consider documentation the most critical of technology

transfer needs. Because documentation is time consuming and expensive to produce, decisionmakers

and modelers alike have tended to assign it low priority, concentrating on the production of ‘bottomline’ information. Without adequate documentation, however, decisionmakers cannot subsequently

determine how the information was generated, nor

evaluate it. Documentation is also crucial for providing individuals in other Federal agencies a means

of determining whether they can use a previously

developed model. A 1974 GAO survey of 710 Federal data-processing personnel and auditors who

reported problems due to inadequate documentation, revealed that nearly one-third (233) of the

related programs had to be totally rewritten, and

one-sixth (1 27) of the automated data-processing

systems had to be redesigned. Moreover, more than

half (428) of the documentation-related problems

resulted in substantial delays in the completion of

assignments. 5

51mprowrmmt .Vee&d m Documenting Computer 5j@ern.s, General Accounting Office, October 1974, pp. 6-7.
Ch. 4—Federal Use and Support of Water Resource Models ● 75

Concern over the inadequacy of current levels

of documentation for Federal models is corroborated by the 1974 NSF survey, and by a 1979 survey of 39 modelers conducted for the National

Bureau of Standards (NBS). NSF found that for

about 75 percent of the 222 surveyed models, the

documentation supplied by the developer was inadequate to enable nonproject personnel to set up

and run the model. G Developers surveyed by NBS

showed strong support for governmentwide model

documentation guidelines, including the specification of a documentation plan in model development

contracts, detailing the documents to be produced,

the resources allocated, and personnel responsibilities. 7

Training opportunities are essential to developing

in-house capabilities for running and interpreting

models. Unless training is supplied, agencies are

totally dependent on model developers for modelgenerated information. The 1974 GAO survey

found the third-largest source of major modeling

problems to be “lack of qualified personnel to

operate and maintain the model. Workshop participants were similarly concerned to find ways of

encouraging agencies to provide adequate resources

for model-related training, Different levels of training for decisionmakers and for users were repeatedly advocated, the latter type to incorporate “handson ‘‘ interaction with the model and ‘ ‘one-on-one’

instruction where possible.

Workshop participants also pointed to the routine

provision of technical assistance as an inexpensive

means of troubleshooting in model use, The availability of knowledgeable individuals to answer simple ‘ ‘over-the-phone’ questions can save manhours and computer time that are otherwise lost

to trial-and-error attempts to operate the model.

For more complex models and/or modeling problems, participants suggested temporarily assigning

developers to user organizations to facilitate the initial setting-up of the model.

bFromm, Hamilton, and Hamilton, op. cit. , p. 6.

‘Saul I Gass, ‘ ‘Assessing Ways to Improve the Utility of LargeScale Models, ‘‘ in Valldutlon and Assessment Zssues of Ener~ Models, ~’a -

tional Bureau of Standards, Special Publication 569, February 1980,

p, 251.

Maintenance and Dissemination

The current structure of Federal modeling activities gives agencies little incentive to consider potential uses for models once they have served the agency’s primary purpose. Consequently, most models

are not updated, or maintained, to keep them technologically current, nor is information about their

existence or availability circulated among potential users in government and the private sector. One

of the most frequently voiced concerns of workshop

participants was the difficulty of locating and obtaining existing Federal models. Many modelers

considered improving access to current models a

higher priority than improving and developing new

ones. Participants generally agreed that lack of information regarding the availability of Federal models is a significant barrier to their widespread use.

Participants also noted the Federal Government

lack of commitment to maintaining the models it

has already developed. They stressed the need to

develop mechanisms and/or organizational units

with routine responsibilities for periodic model

analysis and updating. The need to inform model

users of changes made to a model was also considered to be neglected in current agency procedures.

Interagency Coordination

Federal modelers identified the lack of interagency coordination as a major bottleneck in efforts to

advance the state of the modeling art. Managers

tend to be unaware of the modeling and model development projects being supported by other agencies, a situation that may lead to decisions to build

models already in existence or in process of development. A certain amount of duplication in modeling has potentially beneficial effects—it fosters a

kind of competition from which more accurate and

efficient modeling techniques can result. However,

for highly complex modeling tasks, interagency

pooling of resources and technical expertise could

facilitate greater and more rapid advances than are

possible when each agency functions independently.

As explained in a USDA Soil Conservation Service background paper for the OTA modeling workshops, “There would be value in encouraging

broader use of certain water resource models among
76 ● Use of Mode/s for water Resources Management, Planning, and policy

Photo credit: @ Ted Spiegel, 1982

Federal agencies with modeling expertise and computing facilities provide extensive assistance to State and local

users, as well as to users in other Federal offices. Miniature lights on these panels at USGS computer facilities in

Reston, Va., glow when telephone hookup lines to computers are currently in use

Federal agencies both to reduce duplication of mod- only means of assuring that high-quality models are

cling effort and to obtain the benefit of multiple brought to completion. The creation of adequate

agency comment following their use. data bases to support sophisticated modeling proj -

Further, for highly complex and interdisciplinary ects, in particular, calls for interagency coordination and planning. modeling, interagency participation may be the

CURRENT APPROACHES TO FEDERAL

MODEL MANAGEMENT

This section reviews the Federal legislation and arrangements currently responsible for disseminatprogram activities that affect the development and ing water resource models and/or assisting other

use of water resource models. It analyzes the plan- water resource agencies to use them. Because modning framework through which funding is provided cling is an integral part of Federal responsibilities

for model-related work. This section further de- fer water resource analysis, data collection, and

scribes the major organizational and institutional R&D, this section also addresses a number of Fed-
Ch. 4—Federal Use and Support of Water Resource Models ● 77

eral agencies and offices for which the advancement

of modeling capabilities is not a primary objective.

The section is organized according to four major

areas of Federal involvement: 1 ) governmentwide

water R&D policies; 2) governmentwide coordination and dissemination activities; 3) agency-level

modeling activities; and 4) agency-level dissemination activities.

Consideration of Models in

Governmentwide Water R&D Policies

The Water Research and Development Act

of 1978

The Water Research and Development Act of

1978 is currently the major legislative mechanism

for coordinating the development of analytical tools

to address water resource issues. It states the congressional finding that ‘‘the Nation’s capabilities

for technological assessment and planning and for

policy formulation for water resources must be

strengthened at both the Federal and State levels,

and assigns responsibilities to the President and the

Secretary of the Interior for developing a coordinated Federal program of water-related research

and technology.

The act directs the President to:

Clarify agency responsibilities for Federal water

resources research and development and provide

for interagency coordination of such research, including the research authorized by this Act. Such

coordination shall include: 1 ) continuing review

of the adequacy of the Government-wide program

in water resources research and development and

identification of technical needs in various water

resources research categories, 2) identification and

elimination of duplication and overlaps between

two or more programs, 3) recommendations with

respect to allocation of technical efforts among the

Federal agencies, 4) review of technical manpower

needs and findings concerning the technical manpower base of the program, 5) recommendations

concerning management policies to improve the

quality of the Government-wide research effort,

and 6) actions to facilitate interagency communication at management levels (sec. 406(b)).

In addition, the act assigns specific responsibility

to the Secretary of the Interior to:

Develop a five-year water resources research

program in cooperation with the (state water research) institutes and appropriate water entities,

indicating goals, objectives, priorities, and funding

requirements (sec. 103 (b)).

To fulfill these objectives, and other objectives of

the act:

The Secretary shall cooperate fully with, and

shall obtain the continuing advice and cooperation

of, all agencies of the Federal Government concerned with water problems, State and local governments, and private institutions and individuals,

to assure that the programs conducted under this

Act will supplement and not duplicate other water

research and technology programs, will stimulate

research and development in neglected areas, and

will provide a comprehensive, nationwide program

of water resources research and development (sec.

406 (a)).

In assigning responsibility for developing a comprehensive 5-year water resources research program

to the Secretary of the Interior, the act broadly

outlined a new mechanism for coordinating Federal

water resources analysis. Between 1963 and 1977,

such a task had been the responsibility of the Committee on Water Resources Research (COWRR),

under the aegis of the Federal Council for Science

and Technology within the Executive Office of the

President (EOP). Beginning in 1966, COWRR developed and annually updated a long-term program

for water resources research. Its reports recommended priority research areas and were intended

to guide Federal agencies in allocating research

funds.

The 1978 act calls, in general terms, for EOP

to play a lead role in coordinating the conduct of

water resources analysis among the Federal agencies, relying on DOI to develop a research and tech

nology agenda as a basis for EOP decisions. President Carter’s message on science and technology,

delivered to the Congress on March 27, 1979, further directed the Secretary of the Interior and the

Director of the Office of Science and Technology

Policy (OSTP) to determine research priorities for

meeting the Nation’s long-range water needs.
78 ● Use of Models for Water Resources Management, planning, and policy

Development of the Five-Year Water

Resources Research Program

Under the joint direction of DOI and OSTP, interagency policy and working groups summarized

current agency-level programs of water reseach and

short-term priorities in ‘‘Water Research Priorities

for the 1980’s” (April 1979),8 and developed recommendations for improving the Federal effort in

10 broad subject areas in ‘ ‘Interim Report—Priorities in Federal Water Resources Research’

(August 1979).9

“Proposed U.S. National Water Resources Research, Development, Demonstration, and Technology Transfer Program, 1982-87, draft, an expanded version of the agency summaries with projected funding levels for fiscal years 1982 to 1987,

was delivered to the Water Resources Research Review Committee of the National Academy of Sciences (NAS) for review in December 1980. The

NAS evaluation, Federal Water Resource.s Research: A

Review of the Proposed Five- Year Program Plan, was

published in May 1981.

Water resources models figure prominently in

the description of agency research efforts in the

April 1979 and December 1980 documents. The

extent of the Federal commitment to modeling activities is exemplified by frequently occurring references to them in many of the agency reports. EPA,

for example, lists among its research priorities the

need to:

. . . develop, test and validate models for simulating source loads and ‘‘ in-stream’ processes for use

in assessing water quality problems, allocating

source loads, and evaluating alternative management strategies; and expand modeling capability

to include toxics, especially with regard to sediment

processes. 12

8’ ‘Water Research Priorities for the 1980’ s,” Department of the

Intcrlor, Office of Water Research and Technology, April 1979.

9“ Interim Report-priorities in Federal Water Resources Research, Department of the Interior and the Oflice of SC icncc and

Technology Policy, August 1979.

‘0’ ‘Proposed U.S. N’ational Water Resources Research, Development, Demonstrate ion and Tmhnolo,gy Transfer Program, 1982-1987,

Draft, Department of the Interior, December 1980.

~ ~ Ftdma[ Walu ResOurce3 Re~earch A Review of the Proposed Flue- Year

Program Plan, Water Resources Research Review Committee of the

,National Research Council (Washington, 1). C. : National A( acfemy

Prrss, 1981),

1“ ‘Water Rescm-ch Priorities f’or the 1980’ s,” p.67,

Agencies also report needs for information and

models in areas where, lacking authorization to

fund model development, they must rely on the

modeling effort of other agencies. The Soil Conservation Service of USDA pointed out the need

‘ ‘to improve estimates of erosion potential and

nutrient loss from forest and rangelands; similarly,

the Department of Transportation stated that it

could benefit from work to “develop operational

two-dimensional model simulating stream degradations, aggravation, and local erosional processes.

Both documents are compendiums of individual

agency research plans; consequently, opportunities

for interagency coordination of modeling efforts,

or other research and technology-related activities,

are not addressed. In addition, neither document

describes agency activities in sufficient detail to permit a determination of levels of funding allocated

to modeling activities, or the means used to coordinate modeling and related support efforts within

each agency. No summary of State needs was included in either document, and it is difficult to

determine how or whether the State water resources

research institutes’ 5-year programs were considered in formulating the agency research plans

that constitute the December 1980 draft.

The ‘ ‘Interim Report’ of September 1979 sets

out goals and general priorities for governmentwide

water resources R&D. It indicates many areas in

which improved modeling capabilities are needed,

including conjunctive ground water/surface water

systems, aquatic ecosystems, environmental impacts to wetlands, chemical transport, verification

of water quality and wasteload allocation models,

flood plain delineation, streamflow forecasting, and

hydrological/meteorological forecasting. No attempt

is made, however, to relate general goals to specific

agency activities, or to recommend divisions of responsibility and funding allocation levels among

agencies. The report provides broad guidelines to

agencies conducting research and analytical activities, but addresses none of the management concerns outlined in the 1978 act.

The differences between the two agency compilations and the ‘ ‘Interim Report’ suggest one of the

major difficulties in creating an overall Federal

‘ ‘Ibid, p. 9.

141hid, p. 63.
Ch. 4—Federal Use and Support of Water Resource Models ● 79

strategy for water resources R&D. From the perspective of each Federal agency or program, models

and research are valuable primarily for their contribution to specific program objectives. Alternatively, an overview of national water resource

problems can show areas in which lack of computerbased information prevents important advances in

identifying needs, creating cost-efficient control

strategies, and developing better administrative and

legislative tools, Making agencies more responsive

to such national-level concerns requires concerted,

ongoing efforts at highest management levels to integrate overall objectives into routine agency decisions and funding allocation procedures.

The NAS evaluation of the proposed 5-year program plan also sets out to define broad problem

areas in which further water resources research is

needed. It focuses, however, on analyzing inadequacies in the December 1980 draft, and identifying institutional constraints to the development and

implementation of a coordinated long-range Federal

plan. The NAS study points out the inadequacies

of a focus on research per se—rather than on a

broader range of analytical and support needs—

as a major defect in the DOI/OSTP coordinating

effort.

The report by its title purports to cover more

than ‘ ‘water research’ ‘—namely, ‘‘development,

demonstration, and technology transfer, ’ although

these terms are not defined. Rigorous attention is

not given to distinguishing those separate activities

in the program statements of the individual agencies, and no overall assessment of these activities

is included in the program. The instructions to the

agencies mentioned only research. 15

The NAS study further concludes that the directives of the 1978 act are insufficient in themselves

to provide a basis for coordinated Federal approaches to water resource R&D.

The deficiencies noted in the draft of the fiveyear program report are convincing evidence that

the ad hoc approach to management of the Federal

water research program will not yield the results

expected by Congress when

Research and Development

it enacted the Water

Act of 1978.16

OTA’S survey of Federal water resource modelers and of related studies suggests that directives

for formulating an overall Federal plan for water

research and technology should specifically address

the relationship between research and developing

usable analytic tools. Priorities and allocation of

funding and manpower need to be set for both kinds

of activities, as well as for mechanisms to transfer

modeling expertise and increase model availability to Federal, State, local, and private sector users.

Role of the State Water Resources Research

Institutes in Coordinating Federal

Water R&D Policy

The Water Resources Research Act of 1964, and

its successor, the Water Research and Development

Act of 1978, provided for the establishment of a

network of State water resources research institutes

at a designated land-grant college or university in

each State. Under the auspices of the Office of

Water Research and Technology (OWRT) in DOI,

the institutes have funded a wide variety of research

programs in water resources. Since its inception,

the State Institute Program has involved over

35,000 professionals and students in water-related

research and problem-solving studies. Funding has

been provided by OWRT on a matching basis with

State governments under two separate programs:

1) a basic allocation of $110,000 per State (as of

fiscal year 1980), and 2) a competitive grants program allotting a total of over $5 million (as of fiscal

year 1980). However, for fiscal year 1982, the competitive grants program has been eliminated, while

the basic allocation to individual States has been

reduced to the $110,000 1980 figure. In addition,

OWRT has been scheduled for elimination, and

its duties and responsibilities transferred to other

offices and programs, before the end of the current

fiscal year.

The State Institute Program has proved to be an

efficient, effective means of encouraging a wide

variet y of water research efforts. In fiscal year 1979,

the latest year for which detailed cost statistics are

available, total Federal support of slightly over $21

million elicited a nearly equal commitment of State

—.— ‘I ~“l’herC arc ‘ urrf.nt]~, 51 lnst itutcs-onc pcr state, and add itlt}na!

]nst ltut ions in }$’ashlnqon, D.C , Puerto Rico, Guam, and [hc \’lrgtn

Islands.
80 Use of Models for Water Resources Management, Planning, and Policy

and private funds. During that year, the program

supported the work of about 1,200 principal investigators and about 1,750 student research assistants.

Modeling activities constitute an important component of institute efforts, and increased training

opportunities in model-related skills for water

resource professionals have been one of the program’s major byproducts.

The 1978 act also designates the institutes as the

principal source of information regarding State

water research needs for use in creating the Federal

5-year program plan. Each institute is required to

submit to the Secretary of the Interior for approval

an annual program “developed in close consultation and collaboration with leading water resources

officials within the State’ and ‘‘to cooperate with

the Secretary in the development of five-year water

resource research and development goals and objectives.

The scope of institute activities varies greatly

from State to State. Some institutes focus on analytical work in cooperation with State water agencies; others concentrate on more traditional research

functions. The diversity of the activities and concerns of the 54 State institutes is highly appropriate

to their research missions, but has mixed implications for relaying State agency needs in water resource R&D to Federal policymakers. The institutes

are closely connected to the academic institutions

at which they are housed, and are not alined with

any one State agency. Their freedom from missionoriented concerns and priorities gives them the potential to represent the needs of all the State-level

water resource agencies. However, since the institutes are staffed primarily by research scientists with

professional ties to universities, they are not involved with day-to-day State agency problems.

Existing Governmentwide

Mechanisms for Coordinating

Modeling and Model-Related

Information

Office of Water Data Coordination (OWDC)

Since water resource modeling tends to be highly

data-intensive, model developers and users are particularly vulnerable to problems of data availability. Unless the collection of required data can be

planned simultaneously with model development,

modeling activities must be adjusted to the available

data resources. This makes coordination of water

data collection extremely important to successful

use of water resource models.

Hydrologic data are collected by a large number

of governmental and private entities, normally in

order to serve some specific informational purpose

or in support of established program activities. Historically, such data were collected under methods

and standards devised to suit an organization’s or

agency’s individual purposes, and were stored away

once the organization’s needs for it were met. While

some general-purpose data on the quality and quantity of the Nation’s available water resources were

routinely collected and disseminated by the Water

Resources Division of the U.S. Geological Survey

(USGS), potential users of water data frequently

encountered difficulty in identifying and locating

existing data bases. Afterwards, even when such

data were located, they were often found unusable,

due to collection methods and/or standards of accuracy that failed to meet user requirements.

In 1964, to aid in coordinating water resource

data, the Office of Management and Budget (then

the Bureau of the Budget) issued Circular A-67,

assigning the role of lead agency for such activities

to DOI, which assigned specific responsibility for

this function to USGS. To carry out this responsibility, USGS created OWDC, and gave it the following principal responsibilities:

exercising leadership in achieving effective coordination of water data acquisition activities;

undertaking continuing and systematic review

of water data requirements and activities;

preparing and keeping current a Federal Plan

to aid in coordinating agency water-data acquisition efforts;

maintaining a central Catalog of Information

on Water Data and on Federal activities being

planned and conducted to acquire water data;

and

designing and operating a national network

for acquiring data on the quality and quantity of ground and surface waters, including the

sediment loads of streams.

Major programs of OWDC most relevant to

modeling needs include:
Ch. 4—Federal Use and Support of Water Resource Models ● 81

Photo credit: @ Ted Spiege/, 7982

Banks of disk-drive units retrieve and store information at USGS headquarters in Reston, Va.

Federal Plan. —A key coordination document,

summarizes the plans and needs of agencies acquiring or using water data. It brings these plans

together at the level of each of the 21 national

regions of the Water Resources Council—the regional plans are then assembled as the basis for the

unified Federal Plan. Ongoing field-level review

and Interagency Advisory Committee oversight are

employed to achieve coordination at local and national levels.

Catalog of Information on Water Data.—A

computerized file of information about water data

activities. Currently, the catalog is divided into four

sections: 1) streamflow and stage; 2) quality of surface water; 3) quality of ground water; and 4) aerial

‘8’ ‘Plan for Water Data Acquisition by Federal Agencies Through

fiscal year 1982, Office of Water Data Coordination, USGS, Department of the Interior, August 1980.

investigations and miscellaneous activities. Special

indexes such as the four-volume ‘‘Index to Stations

in Coastal Areas’ have also been published. Another special index currently being prepared covers

water data acquisition activities in the major coal

provinces of the United States.

National Water Data Exchange (NAWDEX).

—A national confederation of water-oriented

organizations working together to improve access

to water data. Developed by a working group of

the Interagency Advisory Committee on Water

Data, it has a function which the Catalog of Information on Water Data only partially fulfills-that

of assisting users of water data in identifying, locating, and acquiring needed data. NAWDEX members are linked so that their several water data

holdings may be readily exchanged for maximum

use. Coordination and overall management for the
82 . Use of Models for Water Resources Management, planning, and policy

program is provided by a central program office

within the Water Resources Division of USGS.

Water Resources Scientific Information Center

(WRSIC)

An early priority of COWRR was the establishment of a central facility to collect and disseminate

information relating to water resource analysis. In

response to its recommendations, under the authority of the Water Research and Development Act

of 1964, DOI created WRSIC within OWRT (then

the Office of Water Resources Research) in 1966.

WRSIC is primarily a management and support

unit that funds the compilation of information by

other organizations. It does not collect and store

published material, nor does it have a staff of abstracters, indexers, and support technicians. It contracts with a variety of governmental and private

organizations to collect information under service

and funding agreements, and produces publications

and computerized records by arrangement with additional government organizations. Its two major

information systems have been the Selected Water Resources Abstracts (SWRA) and the Water Resources

Research in Progress File. Recent budget reduction initiatives have cut WRSIC appropriations

from over $900,000 for fiscal year 1981 to under

$600,000 in fiscal year 1982, and have eliminated

WRSIC support for the Research in Progress File.

Material for SWRA is collected primarily by private centers of competence in particular water resource fields, supplemented by additional information from Federal agencies, State water resources

research institutes, and a commercial abstracting

service. The material is processed at the National

Technical Information Service (NTIS), and made

available in two forms: a journal, SWRA, published semimonthly, and computerized bibliographic retrieval services available through DOI

and private sources. Approximately 15,000 new

bibliographic entries are published and added to

the system each year. The abstracts system currently holds over 150,000 full bibliographic references.

WRSIC also uses the system to produce and publish

an extensive topical bibliography series, and the

OWRT research reports.

The Water Resources Research in Progress File Catalog

is an annual compilation of about 2,500 summary

descriptions of new or substantially revised research

projects in water resources. Until October 1981,

the file was compiled by the Smithsonian Scientific

Information Exchange (SSIE) from material voluntarily registered there by Federal and other research

organizations. NTIS has recently been given responsibility for compiling the Research in Progress

File, and is developing procedures to streamline the

compilation process. Since file entries refer to ongoing work, the file reports projects substantially in

advance of SWRA, which can reflect only published

findings. File information is accessible through

computer retrieval systems at NTIS and through

the private sector.

Both the Research in Progress File and SWRA

contain information about models and modeling

activities. However, since they are designed for

much broader purposes, abstracts and research

projects are referenced originally by subject areas

—and are cross-referenced only under the general

category, ‘‘model studies. It would be extremely

difficult for these general bibliographic reference

services to adequately address the specialized nature

of modeling needs without making substantial

changes in their capabilities—such as the ability to

store and distribute computer programs.

National Technical Information Service

NTIS of the Department of Commerce serves

as the primary source for the public sale of Government-sponsored research, development, engineering reports, machine-processable data and related

software. It adds approximately 70,000 new reports

annually to an information collection of over 1 million titles, of which over two-thirds are computer

retrievable. NTIS publishes a number of user-information reports to keep users informed of available

material, including a comprehensive biweekly journal summarizing new publications, 26 weekly abstract newsletters, with annual indices, and over

2,000 bibliographies. NTIS analysts are also available to match user requests to available material,

using online computerized master files.

In addition, the statutory mission of NTIS includes the collection and sale of data files and computer programs from Federal sources. These are

made available to users on magnetic tape, while

documentation in the form of user and program-
Ch. 4—Federal Use and Support of Water Resource Models ● 83

ing manuals is available in printed copy or on

microfiche. Models must already be documented

in order to be listed in NTIS files. Computer-based

material is primarily indexed under the subject

area(s) to which it refers—a retrieval system was

developed specifically for locating computer tapes

of models, but was poorly suited to this purpose.

More recently, NTIS files of computer models have

been combined with those of the General Services

Administration (GSA) Federal Software Exchange

Center (FSEC), as described below.

Following the elimination of SSIE, NTIS has recently been designated to compile the Research in

Progress File, the water research portion of which

was previously funded by WRSIC. As no funding

was allocated to NTIS for compiling the file, the

agency can only accept Notifications of Research

in Progress for which submitting agencies have provided indexing and other preparatory work for computer retrieval.

Because water resource models constitute only

a minute fraction of the entries in the NTIS system,

proposals for increasing general NTIS capabilities

to locate them and advise potential users about their

functions are difficult to justify. As a general-purpose information center that is obligated by law to

recover its costs from sales and distribution of product and services, NTIS cannot affort to serve as

a modeling resource center. With regard to computer programs, it can be an effective mechanism

for the distribution of an already-known model, but

its functions are too broad to permit its effective

use as a focus of modeling expertise and information.

GSA Federal Software Exchange Center

The Brooks Act of 1965 (Public Law 89-306)

gives GSA authority to develop governmentwide

guidance for automatic data-processing activities.

Under this authority, GSA amended the Federal

Property Regulations to create a Federal Software

Exchange Program in February 1976. To implement the program, GSA created FSEC by interagency agreement with NTIS, using funding from

the GSA automatic data-processing revolving fund.

The Federal Property Management Regulations

require agencies to submit abstracts of computer

programs considered usable by other agencies to

FSEC at NTIS. The regulations specify that these

computer programs must have been operational for

at least 90 days, and require agencies to provide

particular forms of documentation with the abstracts. FSEC currently compiles the submitted abstracts into the GSA Software Exchange Catalog, and

sets prices for Federal, State, and local government

agencies wishing to use the listed computer programs. Subscriptions to the catalog are provided

for a $75 annual fee.

No mechanisms exist, however, for enforcing

participation in the software exchange program.

The determination of which programs are suitable

for interagency use rests with each agency, and

GSA has authority to do little more than persuade

agencies to submit abstracts. Consequently, responses to the program have not met expectations

—while GSA and NTIS officials planned for the

receipt of up to 7,000 abstracts in fiscal year 1977,

the first year of the center’s operation, the inventory currently contains only about 1,300 abstracts,

a small percentage of the software suitable for

exchange.

For a program to be included in the Software Exchange Catalog, agencies must submit a tape of the

actual program, documentation, and an information sheet specifying basic program characteristics.

All software packages are routinely reviewed for

completeness, but FSEC staffing levels do not generally permit the evaluation of submitted programs.

Consequently, the FSEC inventory consists primarily of general submissions of unknown quality. Only

a very small percentage of inventoried programs

have been tested and enhanced by GSA, or are considered to be of special significance and known reliability. Moreover, to satisfy agency fears about receiving large numbers of direct inquiries regarding

computer programs, software exchange program

regulations further specify that the developer of submitted computer programs will not be identified to

purchasers without the developer’s prior consent.

Providing technical assistance to users has not

been included as a major part of the FSEC mission—less than one staff-year of time was budgeted

for this purpose for the first year of the center’s

operation. GSA’s policy of recovering the costs of

the program through sales of computer software appears to preclude higher levels of assistance. How-
84 . Use of Models for Water Resources Management, planning, and policy

ever, since potential users frequently have no access to developers under the program, many available models will remain unused for lack of the technical guidance required to adjust them to particular

user needs. An early GAO report on FSEC activities (1978) summarizes:

The GSA Software Exchange Program, as presently operated, is primarily a catalogue sales operation. In our opinion, many agencies will not buy

software from this source because adequate techn ical assistance is not being provided.

To enhance intra-agency software use, and expand the base for submissions to the FSEC inventory, FSEC has recently begun to offer technical

assistance to Federal agencies on a reimbursable

basis for establishing internal software inventories,

and setting up coordination mechanisms for software development and use. FSEC is also negotiating with various specialized groups to catalog

software in topical categories, geared to specific

classes of users.

Existing Support Structures for

Agency-Level Modeling Activities

The majority of Federal agencies that currently

use water resource models lack comprehensive strategies for developing, using, and disseminating these

tools. Modeling activities and expertise are dispersed throughout most of the agencies surveyed

by OTA, with little apparent coordination, communication, or sharing of resources among individual

modeling projects. However, two of the major users

of water resource models—the Corps of Engineers

and USGS—have developed programs that integrate all major phases of modeling activity, and

function as a focal point for serving the modeling

needs of nonagency users.

The two organizations employ widely divergent

approaches for supporting model-related activities.

The Hydrologic Engineering Center (HEC) of the

Corps of Engineers is a discrete organizational unit

that develops and supports a limited number 01 carefully selected models for use in a wide variety of applications, By contrast, model development if dispersed

throughout the research activities of the Water

—-—

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puta /’ro~ram .\’harlnq, (;tncral At { (junting (J1’fi( c, January 1978, p. 13.

Resources Division of USGS. A problem-solving

focus is provided by the USGS Federal-State Cooperative Program, which assists State and local

agencies in acquiring needed water resource information on a case-by-case basis, using analytical

resources throughout the division to develop sitespecific models that deal with the particular problem at hand. These two approaches are described

in greater detail below to illustrate the major options available for agencywide coordination of modeling activities. In addition, a third organization—

the Instream Flow Group of the U.S. Fish and

Wildlife Service—is presented to illustrate the

potential for advancing model use and modeling

capabilities through innovative interdisciplinary, interagency analytical work.

Army Corps of Engineers’ HEC

Established in 1964, HEC provides assistance in

applying state-of-the-art technology (primarily

mathematical models) to current hydrological planning, design, and operation problems. While

HEC’S initial purpose was to provide hydrological

engineering services to the Corps of Engineers 52

offices, it currently supports the development and

implementation of a broad range of water resource

analysis and planning techniques. Services are provided extensively to non-Corps of Engineers users

—private firms; other Federal, State, and local government organizations; universities; and foreign

organizations—which currently account for over 80

percent of HEC model use.

HEC professionals locate, evaluate, and/or develop new procedures and techniques for analyzing

water resources; develop and maintain 12 major

computer models; teach currently available techniques and model use in formal training courses;

and assist Corps of Engineers offices and others in

applying models and techniques to current studies.

To provide readily accessible user assistance, HEC

assigns each of its major models to one or more

engineers, who answer user questions over the telephone and handle unforeseen difficulties that may

arise.

HEC has evolved a number of basic guidelines

to ensure the widest possible use for the models it

develops and/or maintains. Models are designed

for general use, so that most problems in a field

of interest can be solved with the same model, and
Ch. 4—Federal Use and Support of Water Resource Models ● 85

Photo credit: @ Ted Spiegel, 1982

Extensive field investigations, analyses, and public

participation are part of the planning process for the

Army Corps of Engineers’ study of the Passaic River

Basin. HEC provides analytical support for Corps

studies, using a wide variety of modeling and

other planning techniques

require little or no program modifications. Commonly accepted techniques are used where possible, and a variety of approaches is provided within

an overall modeling package to suit individual needs

and preferences. All programs are written in a commonly accepted computer language (FORTRAN

IV), and are also designed to be easily transportable to a wide variety of computer types.

The ease with which the model can be used is

also an important design criterion. To document

models, HEC develops both user’s and programer’s

manuals. The user’s manual is written both to allow

the beginner to use the model easily and to permit

experienced users to employ the model for complex problems. The procedures for entering data

into the computer are designed for simplicity, and

are thoroughly described in the user’s manual.

HEC distributes copies of its models and documentation without charge to a variety of users;

private firms are charged a nominal fee for reproduction and handling costs. A November 1976 survey showed an annual distribution of approximately

700 model copies, and found that over 2,700 copies

of HEC models were still in use by the offices that

received them. HEC also publishes newsletters,

professional papers, computer program abstracts,

and training course notebooks to promote the use

of its models.

Training courses are an integral part of the HEC

user assistance program. The center provides 24

weeks of training courses annually for Corps of

Engineers staff, reserving approximately 10 percent of the space in these courses for non-corps of

Engineers personnel. A number of the HEC-developed courses have also been adopted for use by

U.S. and Canadian universities. Fifteen of the

HEC courses have been videotaped; tapes and instructional material are available for loan, and may

be used by visitors to HEC in conjunction with

individualized instruction from center staff. Despite

these efforts, however, HEC staff acknowledge that

insufficient training is currently available to the

non-Corps of Engineers user.

USGS Water Resources Division

USGS is a service-providing organization

charged with collecting data on and analyzing the

Nation’s physical resources. Its Water Resources

Division collects long-term multipurpose data on

surface water, ground water, water quality, and

water use; performs special interpretive studies of

the physical, chemical, and biological characteristics

of water; and conducts appraisals for environmental

impact evaluation, energy development, coastal

zone management, subsurface waste storage, waste

utilization, land-use planning, flood plain management, and flood warning systems. Water resource

models are used in all phases of the divisions activities, and are an integral part of its analytical capabilities.

The division undertakes a substantial amount of

data gathering, resource investigation, and research

for general use throughout the Federal Govern-
86 Use of Mode/s for Water Resources Management, Planning, and Policy

ment. It also carries out work to meet the analytical

needs of other Federal agencies on a cost-reimbursable basis, involving funding tranfers of nearly $30

million in fiscal year 1978. Nearly half the division’s

budget, however—$70 million for fiscal year 1978

—was involved in activities carried out for the Federal-State Cooperative Program. The program,

funded on a 50-50 basis by the division and State

and local governments, provides data, information,

and analyses to over 600 non-Federal agencies, concentrating on problems whose solutions are of

mutual benefit to Federal, State, and local water

resource professionals and decisionmakers. More

requests for studies and offers of matching funds

are received by the division each year than can be

undertaken under current funding levels; decisions

and negotiations regarding projects are made on

a decentralized basis through 47 district offices.

Most arrangements for undertaking studies are formalized with a simple one-page standard cooperative agreement.

Research and analytical work for the cooperative

program is implemented under USGS direction,

principally by Water Resources Division staff.

These activities take place primarily at the division’s

regional centers in Reston, Va., Lakewood, Colo.,

and Menlo Park, Calif.; at the Gulf Coast Hydroscience Center at Bay St. Louis, Miss.; and occasionally in other sections of the country as needed.

The combination of decentralized planning and

coordinated interdisciplinary analysis at central

locations allows the program both to be responsive

to real-world problems and indications of emerging priorities, and to pool manpower and expertise in the relatively small field of hydrology.

When a model is needed to perform a particular

analysis, USGS professionals develop one to suit

the specific site characteristics under study. Thus,

each model developed by the division is an individually tailored, single-use model, though it may

often be based in part on a previously developed

research prototype or an earlier modeling effort.

Models and model-related activity account for between 10 and 12 percent of the Water Resources

Division operating budget—from $12 million to $15

million was spent on applying models to specific

problems, and from $3 million to $4 million on research, in fiscal year 1979.

Photo credit: @ Ted Spiegel, 19S2

USGS investigations of water problems are often coupled

with laboratory resaarch and modeling activities to

provide the information necessary for a thorough

analysis. Here, a USGS research scientist demonstrates

computer-controlled lab equipment used to make

calculations for the study shown in foreground

One of the keys to the strength of the USGS effort is the reputation for impartiality enjoyed by

the division’s studies. Many of the projects it undertakes are associated with controversies among

conflicting interests. Because the division’s analyses

are perceived to be relatively free from mission-oriented biases, its results tend to be accepted by all

parties to interstate, intrastate, State-local, and international disputes.

USGS also provides extensive hydrological and

water resource-related training. Courses are conducted primarily at the USGS National Training

Center at Lakewood, Colo., and include a large

number of sessions on modeling surface water,
Ch. 4—Federal Use and Support of Water Resource Models 87

ground water, and water quality. Open to personnel throughout the Federal Government and from

State agencies and international organizations,

courses are geared toward various levels of professional expertise, some of them designed for administrators, others for technicians and resource specialists. Nationally and often internationally recognized

scientists and engineers from the Water Resources

Division serve as the main instructional staff for

training sessions. Experts from other divisions of

USGS, other Government agencies, universities,

and private industry also serve as lecturers and

special consultants.

Cooperative Instream Flow Service Group

The extensive development of water resources

in the Western United States over the past 15 years

has had major effects on the availability of water

for instream uses such as recreation, and fish and

wildlife needs. During this period, concern over

rapid decreases in instream water availability created broad-based expressions of need for a comprehensive source of information and expertise on

standard tools for analyzing instream water needs.

Such concern reached major proportions by the

mid- 1970’s— particularly in the Pacific Northwest,

where protection of the anadromous fish resource

has been an acute problem for many years.

During the early 1970’s, a number of entities engaged in analyzing instream flow problems both

from a technical and legal/institutional perspective.

The general response of natural resource management agencies, and the U.S. Fish and Wildlife Service in particular, was to organize groups of fisheries

or wildlife biologists to make suggestions to the

water management community. This approach

proved relatively unsuccessful, as resource managers were not inclined to give strong credence to a

solely ‘ ‘biological’ perspective. As an alternative,

the Office of Biological Services within the Fish and

Wildlife Service proposed to develop an interdisciplinary, service-oriented center for instream

flow analysis, drawing personnel from numerous

Federal and State Government agencies. Funding

to create this center— the Cooperative Instream

Flow Service Group—was eventually provided

through EPA for fiscal years 1976 through 1979.

Funding is currently provided directly by DOI.

Potential users of Instream Flow Group (IFG)

services identified two major needs: 1) information

on biological and hydrological aspects of instream

uses; and 2) information on institutional means currently (or potentially) available for ensuring adequate stream flows. Satisfying these needs required

the creation of a team of personnel encompassing

the biological, physical, and social sciences to

gather, collate, and disseminate information on instream uses. Model developers and users were also

considered a necessary part of the team effort, in

order to create usable mathematical tools for instream analysis. Staffing for IFG was accomplished

through the Fish and Wildlife Service, State agency personnel recruited under the Intergovernmental

Personnel Act, and detailees from other Federal

agencies.

Since its inception, the group has concentrated

on transferring information on instream uses via

computerized data retrieval systems, library functions, preparing information papers, training, and

providing technical assistance on various aspects

of stream flow protection. Two of its major analytical efforts have been in developing methods to:

1) analyze the effects of incremental changes in flow

on instream uses such as fish and wildlife habitat;

and 2) analyze tradeoffs between instream and offstream uses as part of regional water assessments.

In the first area, IFG has developed the instream

flow incremental methodology, an analytic approach to evaluating changes in the fish-carrying

capacity of stream reaches. This methodology has

been widely adopted for use in Western and Midwestern States. For the second area, work is in progress for a regional reconnaissance method to evaluate general stream characteristics within a water

basin. Using the Upper Colorado River Basin as

a case example, the group is attempting to develop

a unified basin modeling approach as a decisionmaking tool to determine the cumulative effects of

various water management schemes.

The group provides two types of assistance to improve the level of competency among users of its

computer-based models. First, it offers an array of

training opportunities designed to inform participants

about the basic issues, develop an overview understanding of solutions to the problem, and finally,
88 . Use of Models for Water Resources Management, Planning, and Policy

provide instruction in using computer-based

models. The group maintains an extensive training program throughout the Western United States

on such subjects as western water law, strategies

for protecting instream flows, and negotiating instream flows. In addition, the group offers training in the use of modeling technologies. For example, its instream flow field techniques short course

and its computer analysis short course are designed

to give the user the technical competence required

to conduct analyses of instream flow requirements.

Second, IFG provides technical assistance. This entails helping users who are engaged in instream flow

analysis to develop study plans, make measurements, analyze data, develop and present recommendations, and implement them. Technical assistance also involves assisting State and Federal

water administrators in determining areas and opportunities for factoring instream uses into State

water plans or land management plans.

IFG officials attribute the group’s success to its

strong interdisciplinary focus, the quality of its personnel, clear identification of the problems to be

addressed, and frequent interaction among staff

members and group leaders. The communication

engendered among professionals in a number of

disciplines is considered a vital prerequisite to devising methodologies, solutions, and recommendations

credible to the wide range of interests that are party

to water resource management decisions.

Agency-Level Mechanisms for

Providing Information on and

Access to Existing Models

A number of mechanisms are currently used in

various Federal agencies for making model-related

information available to users. Such services may

range from simple directories of available models;

to user support groups for transferring modeling

technologies; to clearinghouses that match user

needs to available models, test and evaluate modeling systems, and provide user training. Four major

agency efforts are described below: 1 ) the International Clearinghouse for Groundwater Models

(ICGWM); 2) the EPA Stormwater Management

Model (SWMM) User’s Group; 3) the EPA Center for Water Quality Modeling; and 4) the USDA

Land and Water Resources and Economic Modeling System (LAWREMS). Each represents a substantially different approach to managing modelrelated information and improving user access to

existing modeling systems, and addresses different

kinds of user needs.

International Clearinghouse

for Groundwater Models

Studies begun in 1975 at the Holcomb Research

Institute indicated that, while significant progress

had been made in developing and using numerical

models for ground water-related resource management, major gaps existed between the need for and

the existence and actual application of ground water

models. Access to existing models, and identifying

models designed for specific applications, were

observed to be serious problems. The gulf between

model developers and model users needed to be

closed by developing mechanisms for transferring

modeling technology from experienced modelers to

others needing these important analytical tools.

Further research work, funded by EPA and the

Scientific Committee on Problems of the Environment, developed guidelines for establishing a clearinghouse to assist users of ground water models,

and an outline of the primary objectives and services of such a center. ICGWM became operational

when EPA funded a 3-year project to staff and fulfill

the clearinghouse objectives at the Holcomb Research Institute. The project is intended to test the

utility of the clearinghouse approach to technology

transfer using ground water models as an example.

The clearinghouse concept is based on the idea

that a central information source can greatly reduce

the effort normally required to acquire model information. Through the clearinghouse, the potential user can be exposed to all levels of available

technologies and can expeditiously determine which

is most appropriate for his purposes. Further, a

clearinghouse provides a natural setting for testing

and evaluating models, and for education in model

applications, operations, and theory for nontechnical and technically trained personnel alike.

The first major activity of ICGWM was to develop a ground water model information search and

retrieval system. A model annotation form—a detailed checklist containing both general and specific

model characteristics—was circulated international-
Ch. 4—Federal Use and Support of Water Resource Models . 89

ly to known model developers, with a request to

complete the form by checking off those characteristics that apply to their models. These forms were

used to develop a computer-assisted Model Annotation Retrieval System (MARS). As of February

1982, MARS had over 400 unique model annotations— and their number is constantly growing.

To access information, the same model annotation form is distributed to interested model users.

The user checks off the desired model characteristics

and returns the form to the clearinghouse, where

MARS compares it to the stored models and identifies those that meet all or most of the desired

characteristics. This retrieval system is designed to

avoid the complexities that plague traditional

systems controlled by key words. Its success can

be gaged by the fact that user requests for model

information grew from an average of 6 per week

during the first 6 months of operation to 85 per

week as of April 1980.

Moreover, developers have begun to recognize

the commercial value of having their models included in MARS. Evidence of competition has

recently been observed among developers to ensure

that their works are available to potential users

through the clearinghouse.

The second phase of development at the clearinghouse involves the acquisition, evaluation, and recommendation of available models. ICGWM is currently assembling a selection of functional models

that: 1) are available; 2) have been tailored to current key ground water problems; and 3) have been

tested for accuracy, usability, and transferability.

A screening process is being developed to examine

models for validation and performance, and to create documentation guidelines for model software.

In the process, close attention will be given to the

model user’s manual compiled by the model developer.

The other major activity started during the second phase of development is a series of workshops

on ground water modeling. The workshops, held

annually at the Holcomb Research Institute, are

structured in a stepwise fashion, beginning with a

general introduction to the applications and limitations of models for policy makers and decisionmakers, and progressing toward advanced mathematical theory in later workshops. The last three

sessions are ‘‘hands-on’ experiences where the attendees vigorously work with computer models and

developers. The first series of workshops was conducted with an enrollment of 140; indications are

that the workshops have been highly successful in

educating water resources professionals about the

potential of models. Future plans call for presenting

the general session at regular time intervals at

regional centers throughout the United States, and

the entire workshop series at various international

locations.

The third phase of development calls for establishing formal international linkages to the center,

and developing financial support to continue the

expansion of the clearinghouse. To the latter end,

ICGWM plans to undertake technology transfer

activities to assist users, operating under an established fee structure for technical consulting work.

However, charges for these services, the workshops,

and the use of MARS are unlikely to cover the cost

of daily operations—outside sources of funding will

need to be secured to support clearinghouse activities. ICGWM officials suggest that an appraisal

of the cost effectiveness of the center will only be

possible once all of its major activities are fully

operational. Over time, however, as demands for

services grow, the clearinghouse is likely to require

less financial assistance from outside sources.

ICGWM officials consider that the clearinghouse

has been successful thus far in making ground water

modeling information accessible, in reducing the

time and effort required for model users to acquire

appropriate modeling tools, and in educating interested professionals about the benefits and limitations of models. The clearinghouse approach also

appears to hold major potential as an effective medium through which new technologies can be transferred.

SWMM User’s Group

EPA’s SWMM is one of the largest and most

comprehensive mathematical models for simulating

storm and combined sewer systems, their associated

storage and treatment facilities, and their impacts

on receiving waters. Its reliability and widespread

availability have made SWMM the most widely

used model of its type in the United States and

Canada, and have been important in increasing the
90 ● Use of Models for water Resources Management, Planning, and Policy

use of models by engineers and planners. The

SWMM User’s Group has been instrumental in

achieving the widespread dissemination and acceptance enjoyed by this important modeling tool.

Initially developed in the early 1970’s, SWMM

is a complex, computer-based model that simulates

the movement of stormwater through a watershed,

determines quantity and quality of runoff, routes

this runoff through a combined (or separate) sewer

system with specified storage and treatment facilities

and operating policies, and thence into receiving

waters, where resulting water quality is quantified.

SWMM is modular, having five computational

blocks—each of which can be used alone or with

other blocks.

When the model first became operational, EPA’s

Office of Research and Development (ORD),

which sponsored the development of SWMM, decided to organize an informal user’s group as its

principal means of technology transfer. ORD recognized that the model’s principal users would not

be EPA staff, but rather the members of the consulting engineering profession, acting on behalf of

EPA, or of State, regional, or local governments,

or industrial and commercial clients. These model

‘‘clients, who are normally free to select the models to be used, generally base their decision on a

model’s ease of use, cost effectiveness, and reliability.

To assure that SWMM would be readily usable,

ORD devoted substantial attention and resources

Photo credit: @ Ted Spiegel, 19s2

Modern urban development has substantially increased both the complexity of urban runoff management and the need

for adequate sewer transport, storage, and treatment of runoff. The Albany, N. Y., skyline provides a dramatic

demonstration of the interactions between built-up urban areas and natural water bodies. Models such as EPA’s

SWMM can be used to assess the impact of Albany’s runoff on flows and water quality levels in the Hudson River
Ch. 4—Federal Use and Support of Water Resource Models 91

to documenting and testing the model before attempting to disseminate it. All or parts of SWMM

were tested in five different locations, and the results

of the tests included in the original documentation.

This, in the judgment of the SWMM developers,

was the single most important factor in gaining acceptance for the model.

The first step in creating a technology transfer

program for SWMM was to set up a mechanism

for distributing the model and its documentation.

Working from a small list of interested people,

ORD offered to duplicate the model and documentation for anyone who sent in a blank tape. Since

1972, over 300 users have received copies of the

program, and perhaps 1,000 copies of the documentation have been sent out. Test data are furnished

with the program to allow each recipient to check

that the model is operating correctly.

User’s Group meetings were seen as the best

mechanism for transferring knowledge among experienced model users and those who were new to

SWMM. The meeting approach combines instantaneous communication of current knowledge with

close interpersonal association and support for

model users.

About 20 individuals attended the first SWMM

User’s Group meeting in early 1973. Since that

time, meetings have been held on a semiannual

basis, and the group membership has grown to almost 500, including representatives from 19 foreign

countries. An informal user’s bulletin, first published in 1973, has been sent out periodically, to

announce meetings or other items of interest.

User’s Group meetings are colloquial and informal in atmosphere, in order to allow a high degree

of interaction between individuals with common interests and problems. To encourage group members to examine other models that may be made

applicable to their problems, at least one presentation per meeting focuses on the use of a different

water quality model. Since 1977, formal User’s

Group proceedings have been published to record

meeting activities.

To maintain and update SWMM, ORD decided

on the services of an outside contractor, rather than

attempting to use in-house resources. The decision

was based in part on the perception that in-house

efforts tend to become self-perpetuating and to stifle

creative change. In addition, the group that maintains the model is available to users for over-thetelephone questioning or detailed consulting on a

normal fee basis. This supplements the informal

free advising network among users, and the availability of User’s Group members to consult on a

fee basis when needed. EPA has resisted requests

to make minor changes in the program. Three updated versions of the model have appeared since

the original; users are encouraged to make other

local changes that they desire.

Initially, training in the use of the model was

sponsored by EPA; since 1976, however, the only

available formal training has been offered privately by various universities. The agency’s experience

has been that, given the support of the User’s

Group, model users are generally willing to train

themselves. In this sense, the User’s Group has

evolved into an inexpensive alternative to agencysponsored training programs.

Costs associated with the SWMM User’s Group

have been relatively low. The group requires about

20 percent of the time of one professional, about

10 percent of one secretary’s time, and about

$5,000 per year to cover printing costs for meeting

proceedings. Other costs include mailing, newsletter printing, maintaining the User’s Group list on

a time-sharing computer, and duplicating the

SWMM program—all of which consume perhaps

$2,000 to $3,000 per year at most. Meeting costs

are minimal-since no travel expenses or honoraria

are paid to speakers—and are covered entirely by

registration fees.

EPA Center for Water Quality Modeling

ORD established the Center for Water Quality

Modeling in 1980 to distribute, maintain, and provide technical assistance in the use of selected EPAdeveloped water quality models. The center, located

at the Environmental Research Laboratory in

Athens, Ga., serves as a focal point for assisting

users in locating and applying models developed

by EPA operating and research programs.

EPA’s use of water quality models increased rapidly in the 1970’s. Separate model development activities within individual EPA offices resulted in a
—

92 . Use of Mode/s for water Resources Management, P/arming, and policy

—

proliferation of seemingly different models, although many models were actually modifications

and/or extensions of earlier modeling attempts. The

lack of a central reference point for model use within

the agency impeded the correction of initial modeling errors, so that errors tended to be propagated

in successive modeling activities. Additional impetus for creating an office to support and maintain

frequently used models came from the growing

need to provide expert technical/analytical assistance to States and EPA regional offices. The success of EPA’s own SWMM User’s Group and the

Corps of Engineers’ HEC in encouraging widespread model use and acceptance pointed to the

large potential benefits to be derived from such an

office.

The center’s initial support role has been limited

to four widely used modeling packages: 1) QUAL11 (a stream water quality model); 2) SWMM/

RECEIV (an urban runoff model); 3) ARM (an

agricultural runoff management model) and NPS

(a general nonpoint source runoff model); and

4) HSPF (a multipurpose hydrologic simulation

program). Center staff provide copies of model

documentation and tapes of the models’ computer

codes to interested users, and relay information

about errors or other problems back to the models’

developers. Center personnel are currently

evaluating a number of models for possible addition to the four packages presently being supported,

and are developing a quantitative r-node] selection

procedure to assist users.

A number of older EPA models are also on file

at the center; however, current manpower limitations do not permit them to be supported or maintained. Computer programs, manuals, reports,

etc., for these models are distributed on request on

a ‘ ‘use at your own risk’ basis. While the center

routinely receives requests for models in this category, it has not checked, corrected or updated them,

and functions primarily as an archive in this area.

For its supported model packages, the center assists users by sponsoring intensive ‘ ‘hands-on’

workshops and technical seminars, taught by experts from the Environmental Research Laboratory

and representatives of the organizations that developed the model under EPA grants or contracts,

Workshops are open to all model users, and the

level of user interest dictates the number of workshops presented. For fiscal year 1980, several workshops were held on the HSPF; two sessions were

held on QUAL-11. A newsletter for informing users

of training opportunities, advising them of modeling errors or updates, and quickly providing additional model-related information was introduced in

September 1980. Superseding and expanding on

the SWMM User’s Group Newsletter, the new

publication has used the audience established by

its predecessor as a base for informing users of the

center’s existence and activities. Current administration policy, however, prohibits the center from

publishing the newsletter.

At present, the center’s manpower resources are

very limited; consequently, it does not offer routine

‘‘online’ technical assistance to all model users.

While limited technical assistance is available on

specific agency problems, and can be provided

through procedures established prior to the center’s

inception, even such requests are generally discouraged. To expand the availability of technical assistance in running models, the center concentrates on

developing user interaction activities, based on the

user group concept, in order to teach users to solve

their own problems. Such an approach has in the

past proved highly successful in encouraging the

use of standardized, widely applicable models.

However, inclusion of additional, more specialized

models in the center’s support role would likely call

for the provision of greater levels of technical

assistance by center staff.

USDA Land and Water Resources and

Economic Modeling System (LAWREMS)

A December 1976 request from the Senate Committee on Agriculture, Nutrition, and Forestry for

USDA assistance in evaluating the department’s

land and water conservation programs provided the

initial impetus for the creation of LAWREMS. As

a followup to its report to the Senate, the USDA

Land and Water Conservation Task Force created

a modeling team composed of representatives from

major USDA agencies, giving it the responsibility

to develop an information system about current

data and analytical capabilities within the department, and to outline future goals and directions for

integrated departmentwide modeling systems.
Ch. 4—Federal Use and Support of Water Resource Models 93

The LAWREMS team developed a computerized directory of data sets and models related to

water and land resource analysis, relying primarily on those created by various USDA agencies. The

team also established a file of related documentation and reports, arranged for ongoing computer

assistance to facilitate access to and transfer of data

and models, and created a small staff to maintain

the directory and provide limited technical assistance to users.

The initial LAWREMS directory contained approximately 300 descriptions of models and data

sets, each of which included such information as

title, agency, an abstract, purpose, keywords, geographic coverage, operational status, name and address of technical contact, and basic technical information. The directory is currently housed within

the Resource Systems Program of the Economic

Research Service.

While LAWREMS support services include direct access to a limited number of models and data

sets within USDA, its primary function is to direct

users to the individuals or organizations that have

developed these tools. The system is intended to

improve communication among program analysts

and researchers about existing data and models,

their use, limitations, and linkages. The existence

of such a system is also intended to encourage the

upkeep, maintenance, and use of existing data files

and models. Services are provided primarily to

USDA analysts working in the area of resource conservation; however, expanding access to include

other USDA personnel, as well as interagency and

non-Federal use, has been envisioned as part of

future LAWREMS activities.

LAWREMS support staff are responsible for

maintaining and updating the directory, and provide some technical assistance to USDA land and

water conservation program evaluators and analysts. Provision of “hands-on” training to a limited

category of users on selected data and analytic Systems is contemplated as part of ongoing staff activities. Staff would also provide assistance in coordinating agency efforts to design new models or modify existing ones, along with identifying data requirements, when information is not available or

accessible from existing sources.
Chapter 5

Use of Models by State Governments
Contents

Summary of Survey Results . . . . . . . . . .*. *. * * 0 . . * . * * * * * + . * * * * *.****.*.

Procedure Used in Conducting the OTA State Modeling Survey . . . . . . . . . .

Trends in Current and Potential State Model Use . . . . . . . . . . . . . . . . . . . . . .

Constraints to Model Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Developing Models To Meet State Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Data Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Lack of Qualified Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Access to Federal Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Reliability and Credibility of Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Model Standardization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Funding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Model Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Documentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

State Model Use in Individual Water Resource Issues . . . . . . . . . . . . . . . . . . .

Surface Water Flow and Supply Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Surface Water Quality Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Ground Water Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Economic and Social Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page

97

98

98

1 0 4

104

105

105

106

106

107

107

107

107

108

108

110

113

114

TABLES

Table No. Page

5. Number of States Indicating Existing or Potential Model Use . . . . . . . . . . . . . 99

6. Rankings of State Model Use for All Water Resource Issues . . . . . . . . . . . . . . 101

FIGURES

Figure No. Page

7. Number of Water Resource Issues for Which States Indicated Current or

Potential Model Use.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

8. Surface Water Flow and Supply Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

9. Surface Water Quality Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

10. Ground Water Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

11. Economic and Social Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Chapter 5

Use of Models by State Governments

State governments have extensive water management responsibilities, ranging from flood control

to prevention of ground water contamination to

comprehensive river basin management. These responsibilities have increased in recent years, due

in part to Federal environmental legislation that

relies on Federal-State partnerships to address a

wide variety of national water resource problems.

The Clean Water Act, the Resource Conservation

and Recovery Act, the Water Resources Planning

Act of 1965, and the Safe Drinking Water Act, in

particular, assign States numerous additional

obligations requiring high levels of technical expertise and highly sophisticated planning and management decisions.

Computer models can significantly aid States in

undertaking these added responsibilities. While several States have sophisticated modeling capabilities,

many State officials acknowledge that the use and

understanding of models by State agencies is far

below the level it should be. To gain a better understanding of factors affecting model use at the State

level, OTA surveyed professional-level personnel

at water resource agencies in all 50 States. This

chapter reports the results of that survey, including

the kinds of models used, the extent of their use,

and the problems encountered by State water resource professionals. It contains:

summary of survey results;

procedure used for conducting the OTA State

modeling survey;

trends in current and potential State model

use;

major constraints to model use identified by

State personnel; and

State model use in individual water resource

issue areas.

SUMMARY OF SURVEY RESULTS

State water resource professionals generally use

computer models developed by others—particularly

Federal agencies. The size, budget, and technical

capabilities of most State water resource agencies

do not permit them to develop models; consequently, State model use depends on having access to

federally developed models and on the availability

of federally sponsored training and technical assistance.

In many States, model use is primarily restricted

to a few well-established, widely available models.

State personnel are often poorly informed about the

availability of models and data, and about technical

assistance available to facilitate model use.

Data inadequacy was the most frequently cited

constraint to effective State model use. While most

State officials indicated that increased Federal funding for data collection would improve State mocieling efforts, they also emphasized the importance

of improving access to Federal (and other State)

data bases.

Low salary levels and high turnover rates were

also stressed as hindrances to States’ efforts to maintain staffs with expertise in modeling. After data

needs, States placed highest priority on increased

federally sponsored training in model use and applications for both technical and managerial personnel. other major State concerns included the need

for Federal sponsorship of simpler models for Statelevel use, and improving the reliability and credibility of models through Federal coordination, clearinghouse activities, and standard-setting.

97
98 . Use of Models for Water Resources Management, Planning, and Policy

PROCEDURE USED IN CONDUCTING

THE OTA STATE MODELING SURVEY

OTA surveyed State agencies responsible for the

supply and quality of freshwater resources in June

1980 to determine the extent of their current and

potential water resource model use. State personnel were asked to identify major problems facing

the States in using models and Federal policy options to improve State model use.

The survey was divided into two major sections.

The first assessed existing and potential State model

use in four major water resource areas: 1 ) surface

water flow and supply; 2) surface water quality;

3) ground water; and 4) economic and social concerns. These areas were further divided into a total

of 33 water resource issues. * Model use for each

of these issues was assessed for three different decisionmaking functions: 1 ) operations and management; 2) planning and policy; and 3) other (primarily research). The respondents were also encouraged to provide additional information on the

role of models for each of the 33 water resource

issues—e. g., the specific regulations for which the

model is applied. Detailed results of this portion

of the survey are compiled in appendix E.

The second section of the survey posed three

broad questions on State model use:

1. Identify the most important needs associated

with water resource model development in

your State, and suggest options available to

the Federal Government to assist your State.

*A discussion of the modeling tc( hniqucs used to analyze each of

thr fbur major rcsoutx c areas, and a review of the prohlcrns and mmlcling ( apahil I t ics MS(X iatcd w lth [’w h of t h[’ 33 water r{’sour( c. issues,

is prc’scntcd in ( h, 6

2.

3.

Identify the most important problems and

needs associated with water resource model

maintenance in your State, and suggest options available to the Federal Government to

assist your State.

Summarize reasons models are or are not used

by your State. Consider the reliability and

credibility of models, and human/institutional

problems. Suggest options available to the

Federal Government to assist your State in

model use.

Surveys were sent to State agencies responsible

for both water quality and water supply concerns

in each State. Since these responsibilities often rest

with different State agencies, surveys were sent to

different agency contacts for water supply and water

quality issues. Names of key agency contacts were

suggested by the State water resources research

institutes.

Six surveys were sent to each State agency contact (two contacts from each State)—a total of612

surveys. Each contact was asked to circulate these

surveys among the agency personnel familiar with

the use of models in the State for the 33 listed water

resource issues. Most of the surveys returned were

submitted independently by individual agency personnel; some of the States, however, returned a single response that had been circulated throughout

the agency.

All 50 States and the District of Columbia returned completed surveys. However, the number

of surveys returned from each State varied from

one to six. A total of 103 surveys were returned.

TRENDS IN CURRENT AND POTENTIAL

STATE MODEL USE

Forty-eight States currently use water resource use only a few of the many models available—primodels. Collectively, the States employ these mod- marily those based on well-established modeling

els to address problems for all 33 identified water techniques like wasteload allocation or ground water

resource issues. However, it is clear that most States supply models.
Ch. 5—Use of Models by State Governments ● 99

The majority of States use models for less than

10 resource issues, and 14 States (28 percent) use

them for five or fewer resource issues. Only onefifth of the States use models for more than 15

issues (see table 5 and fig. 7).

In contrast to their current model use, a majority

of the States identified potential uses for models in

more than 20 of the 33 water resource issues. Nearly

one-fourth of the States indicated that they could

use models for over 30 issues. These statistics indicate that although models are currently used for

a limited range of issues, State offcials see increased

model use as important for expanding State roles

in water resources management, planning, and policy (see fig. 7).

Large discrepancies between existing and potential model use can be highlighted by ranking each

of the 33 resource issues according to the percentage of States indicating current or potential model

use. * Table 6 lists the States’ top 10 existing and

potential water resource modeling uses, and figures

8-11 illustrate the percentages of States indicating

current and potential use of models for each of the

33 water resource issues.

These data indicate several trends: surface water

flow models are currently the most widely used—5

of the 10 top-ranked resource issues are surface

water flow issues. For ground water issues as well,

supply and flow models rather than quality models

receive the greatest amounts of current use. Three

of the top 10 issues, however, are surface water

*These rankings are obtained for each resource issue by totaling

the percentage of States using models to address that issue over the

three specified decisionmaking functions (operations and management,

planning and policy, and research). This combined number better

reflects model use for each issue than percentages reported for any

one decisionmaking category. A State may use sei’eral different models

for the same issue—one for planning and policy, one for operations

and management, and another for research.

Table 5.—Number of States Indicating

Existing or Potential Model Use

Number of issues Existing Potential

0 through 5. . . . . . . . . . . . 14 2

6 through 10. . . . . . . . . . . . 14

11 through 15. . . . . . . . . . . . 12 8

16 through 20. . . . . . . . . . . . 5 7

21 through 25. . . . . . . . . . . . 3 9

26 through 30. . . . . . . . . . . . 2 8

31 through 33. . . . . . . . . . . . 0 12

SOURCE: Office of Technology Assessment,

quality issues. One of them, wasteload allocation,

is the issue for which the greatest number of States

indicated current or potential model use. While

most States do not often employ models to assess

water quality problems, the few problems that have

been studied most—e. g., wasteload allocation and

erosion/sedimentat ion—are widely analyzed using

models. States tend to be frequent users of flow and

supply models, in part because Federal agencies

have been active in developing and applying them.

The Corps of Engineers and the U.S. Geological

Survey (USGS) actively assist States in modeling

efforts for flood forecasting and control, drought

and low-flow forecasting, streamflow regulation,

domestic water supply, ground water supplies and

Photo credit: Environmental Protection Agency

Water quality concerns, and the models used to analyze

them, are increasingly important to State agencies. While

only 3 of the States’ 10 most important model use areas

are currently water quality issues, OTA’S survey of State

officials shows that 7 of the 10 top water modeling areas

are expected to involve water quality in the future
100 . Use of Mode/s for Water Resources Management, Planning, and policy

Figure 7.—Number of Water Resource Issues for Which States Indicated Current or Potential Model Use

5 10 15 20 25 30 35 5 10 15 20 25 30 35 5 10 15 20 25 30 35

1

Ala.

o

Alas. 21

La.

Me.

Ark.

Calif.

Colo.

Corm.

Del.

D.C.

Fla.

Ga.

Hi.

Ido.

Ill.

Ind.

Iowa

Kans

Mass.

3

0

28

Md.

Mich.

1 Minn.

Miss.

Mo.

Mont.

Nebr.

Nev.

33

N.H.

N.J.

N.Mex

N.Y,

N.C.

Okla.

29 31

Pa.

R.1.

32

S.c.

S.Dak.

32

Term.

33

Tex.

15 Utah

14

P

5

Va.

o

33

Wyo.

33

33

29

The number of water resource issues for which States currently use models.

The number of water resource issues for which States could potentially use models.

SOURCE: Office of Technology Assessment.
Ch. 5—Use of Models by State Governments 101

Table 6.—Rankings of State Model Use for Ail Water Resource issues (top ten)

Existing Potential

● Wasteload allocation ● Wasteload allocation

● Ground water supplies and safe yields ● Conjunctive use

● Streamflow regulation . Drought and low-flow forecasting

● Drought and low-flow forecasting ● Impacts on aquatic life

● Flood forecasting and control

{

 ● Ground water supplies

● Conjunctive use ● Waste disposal—ground water

● Impacts on aquatic life ● Agricultural pollution—ground water

● Erosion/sedimentation . Urban runoff

● Domestic water supply ● Erosion/sedimentation

. Instream flow ● Accidental contamination of ground water

a

Tied for fifth place

SOURCE: Office of Technology Assessment.

Figure 8.—Surface Water Fiow and Suppiy issues

Percent

100

80

Operations and 60

management 40

20

0

67 67

51

43 43

23

f “

> .

63 63 61

60 -

61

Planning and

57 55

45

policy 40

20 -

0

100

r

Other

60

40 t 35

20 22

20 ‘ 6

o

Flood Drought Streamflow Instream Domestic Irrigated Off stream Water use

forecasting ancf low regulation flow water agriculture use efficiency

flows supply

Percent of States currently

using models

Percent of States indicating potential model use

SOURCE: Office of Technology Assessment.
102 ● Use of Models for Water Resources Management, Planning, and Policy

Figure 9.—Surface Water Quaiity issues

Percent

100 r

60 -

67 69 Operations ~ - 55 and 55

management

40 -

27

100r

fan L

100 r

60

t

Other 60

t

40 -

25 23 22 27 25

(l

Surface Urban Erosion- Salinlty Agricultural Airborne Wasteload Thermal Toxic Drinking

water runoff sediment runoff allocation pollution materials water

quality quality

m Percent of States currently

using models

Percent of States indicating potential model use

SOURCE: Off Ice of Technology Assessment.

safe yields, and conjunctive use of ground and surface waters.

The characteristics of the top 10 resource issues

for potential model use differ significantly from

those with the highest current use. Instead of flow

and supply, most of the identified problems involve

ground and surface water quality concerns—7 out

of 10 are quality issues. Ground water issues also

stand out among potential model uses; States rank

five of the six specified ground water resource issues

in the top 10.

One reason for the widespread potential reported

for surface water quality models is the extensive

responsibilities that States have acquired for meeting national clean water goals. Models have an important role in States’ compliance with numerous

sections of the Clean Water Act.

Many States stress the need for ground water

models because modeling techniques are often the

only method of determining the characteristics of

major aquifers. However, the lack of ground water

data—particularly for pollutant transport within

aquifers— severely limits the current use of these

models. In general, deficiencies in data and lack

of knowledge of physical processes are more serious

constraints to the use of ground and surface water

quality models than for flow and quantity models.
Ch. 5—Use of Models by State Governments ● 103

Figure IO.- Ground Water Issues

63 61 61

60 - 53

57 57

Operations and

management d .

20 -

0

100 r

60 - 73

67 71 71

59

Planning and 60

policy

40 -

20 -

0

100 r

Other

40 -

25

0

Ground Conjunctive Accidental Agricultural Waste Saltwater

water use contami- pollution of disposal Intrusion

supply nation ground

water

m

Percent of States currently

using models

_ Percen t of States indicating potential model use

SOURCE: Office of Technology Assessment.

Photo credit: @ Ted Spiegei, 1982

Large discrepancies between current and potential use for particular issues suggest that State-1evel

model use is limited by some technical or institutional factor (inadequate data, lack of qualified personnel, poor reliability of the model itself, etc.). For

example, 34 percent of the States currently use

drought and low-flow forecasting models for operations and management, while 67 percent of the

States indicate potential uses for them. Resource

issue-specific assessments of the States’ current and

potential model use appear in the section of this

chapter entitled: “State Model Use in Individual

Water Resource Issue Areas.

State and local water quality agencies have major

responsibility for designing community wastewater

treatment facilities to meet Federal requirements under

the Clean Water Act. Much of the current use of

models—and the perceived need for additional modeling

capabilities—at the State level stems from

Federal requirements for State action
104 ● Use of Models for Water Resources Management, Planning, and Policy

Figure 11 .—Economic and Social Issues

Percent

Operations and G.

management t

41

40 - 35

27 25 25

20 - 8

100

r

80 -

Planning and 60 -

59

policy

40 -

20 - 14

100r

80

t

Other 60

t

4o1-

20

20 - 10 12

2

0

Water costs of cost/ DeveIop- Forecasting Social Risk/ Competitive Unified

pricing pollution benefit ment use implications benefit water use river basin

control implications management

m

Percent of States currently

using models

Percent of States indicating potential model use

SOURCE: Office of Technology Assessment.

CONSTRAINTS TO MODEL USE

State agencies were asked to identify problems

and needs associated with model development, use,

and maintenance in their States, and to recommend

ways to solve problems and meet State needs. The

responses to these questions ranged from general

comments, like ‘‘inadequate data’ or ‘‘lack of qualified personnel, to very detailed descriptions of

problems with specific models or programs. The

following sections highlight trends encountered in

the responses, according to nine subject areas:

1) developing models to meet State needs; 2) data

limitations; 3) lack of qualified personnel; 4) access to Federal models; 5) reliability and credibility

of models; 6) model standardization; 7) funding;

8) maintenance; and 9) documentation.

Developing Models To Meet

State Needs

Respondents frequently recommended that Federal agencies develop models to meet State needs.

Many of the respondents identified a need for sim-
Ch. 5—Use of Models by State Governments 105

ple models. Comprehensive models with large data

requirements are of little use to States lacking the

time, resources, or capability to operate them.

According to the survey, many models cannot

be applied to local site-specific problems. Models

are often designed to simulate an area too large for

State purposes.

Data Limitations

The inadequacy of data was the most commonly identified factor inhibiting State modeling efforts.

Not only does insufficient data constrain the development and application of models, but the use of

unreliable data can produce inaccurate results. For

example, one respondent commented on the impact of using unreliable data for planning advanced

waste treatment plants (AWT):

Millions of dollars have been expended for AWT

based on models which had an inadequate data

base and the resulting treatment levels required

may or may not have been beneficial compared

to the costs.

Many of the respondents noted that the reliability

and credibility of models is only as good as the input data.

The majority of comments concerning data were

general, often simply citing ‘‘insufficient data’ or

“lack of data. The specific responses, however,

fall into several categories:

●

●

●

●

lack of data for specific stages of modeling (i.e.,

development, calibration, verification, etc.);

lack of data for specific issues (i. e., ground

water supply, nonpoint source pollution);

outdated and poorly maintained data bases;

and

unreliable or inaccurate data (e. g., data sampled at the wrong time).

Although the States rely on Federal agencies to

supply a substantial part of the needed data, they

are and expect to be taking the major responsibility for data collection. The major obstacle in meeting the States’ data needs is insufficient funding.

Along with funding problems, a shortage of manpower was another frequently mentioned factor limiting data collection.

Several respondents suggested that a central, or

possibly a ‘‘national’ data bank was necessary.

The States also identified four other important,

though less frequently cited, data problems:

●

●

●

●

poor access to Federal/State data banks;

no data processing (storage and retrieval) capability;

duplication of State and Federal data collection efforts; and

intensive data requirements of many models.

Lack of Qualified Personnel

The States have a severe shortage of personnel

qualified to develop, use, or maintain models. This

limits State modeling efforts in many ways. For

example, some States are unable to modify existing

Federal models to suit their specific needs. Other

States report that their lack of modeling expertise

causes an overreliance on contractors to develop

and apply models.

Part of the problem is due to the prevailing salary

scales for State employees, which make it difficult

to attract and retain qualified personnel. However,

most States did not propose supplemental Federal

funding, but strongly recommended increased technical assistance and training by Federal agencies.

One respondent wrote the following about the

need for training in his State:

The main problem of model implementation in

Indiana is training. The Federal Government

should provide the States with low-cost, application-oriented training opportunities . . . .

Training was considered a high priority by the respondents, second only to data needs. Specific concerns about training fell under three categories:

●

●

●

general education for management-level decisionmakers to understand and appreciate

models;

advanced training for technical personnel to

develop, use and maintain models; and

recommendations for specific courses, e.g. ,

training to use the Environmental) Protection

Agency’s (EPA) Stormwater Management

Model.
106 ● Use of Models for Water Resources Management, Planning, and Policy

Although a few States requested funding for

training, the majority of the States currently rely

on federally conducted training programs. The

workshops and seminars held by the Corps of Engineers’ Hydrologic Engineering Center (HEC) and

USGS were praised by many respondents. One respondent said:

There is only a handful of people in this State,

including the USGS, who can use this type of

model (2 D—ground water flow model). The training courses in Denver (sponsored by USGS) have

been invaluable to us.

The States identified a need for technical assistance at all stages of the modeling effort, from development to maintenance, throughout the range of

water resource issues. Most comments were general, like ‘ ‘State needs model expertise assistance

(Federal) to expedite solutions. ” Other States expressed more specific technical assistance problems,

e.g., “a lack of technical personnel at regional EPA

levels to review and assist the State in model maintenance, or ‘a strong technical assistance program

in ground water modeling technology is needed to

provide the capability to establish flexible predictive mechanisms in ground water contamination

cases,

Access to Federal Models

An important modeling problem common to

many States is the difficulty of obtaining information on or access to Federal models, data, and technical assistance. The States rely heavily on the Federal Government to supply such services to them;

improving access to these services represents perhaps the most easily realizable opportunity for the

Federal Government to contribute to State modeling efforts.

A majority of the comments on accessibility centered on the need for information about and access

to state-of-the-art Federal models. Generally, States

are either unaware of, or unable to obtain, models

and data to help them solve specific problems.

A periodic report or newsletter was suggested as

a means of informing States about Federal modeling activities. Alternatively, the State water resources research institutes could provide a means

of transferring information within each State. A national clearinghouse was also recommended by

many respondents as a good method to make models available to the States. These centers would inventory available models and provide descriptions

to potential users. The clearinghouse could also provide computer programs and documentation to

users. Respondents also suggested that a clearinghouse could serve as a center of technical expertise, model maintenance, and quality control.

Reliability and Credibility of Models

Many of the State respondents pointed out that

the reliability and credibility of models strongly influences their use. Part of this influence is due to

user perceptions. As one respondent stated, “Past

experience with awkward models can impede future

development. On the other hand, another respondent wrote, “As we use the one model we

have, and gain some experience, the reliability and

credibility increase.

State respondents also recognized deficiencies in

technically measurable aspects of model reliability,

in particular, model calibration and validation.

Many respondents mentioned problems with the

reliability of specific models—a typical comment

was, ‘‘current ground water modeling programs

are not sufficiently sophisticated to model the complex situation (especially the ground water-surface

water interface) in this State.

The following concerns were reported as factors

affecting the reliability and credibility of models at

the

●

●

●

●

●

●

●

State level:

the degree of uncertainty in results is not communicated for many models;

the reliability of many models has not been

established through repeated use;

many model parameters are of questionable

accuracy;

assumed values or calculations are sometimes

used in the place of field data;

the state of the art, in some cases, is not advanced enough to provide reliable models;

some decisionmakers are cautious about model

use due to a past history of inappropriate use;

and

model development has been overemphasized

in the past, to the detriment of calibration and

validation.
Ch. 5—Use of Models by State Governments . 107

Although comments on model calibration, verification, and validation were not numerous, most

of the responses had a common theme: the States

have an insufficient amount of time, resources, and

data to perform these functions.

Specific comments included:

. some Federal agencies have encouraged the

use of some models without adequately calibrating or validating them with field data;

● Federal agencies should devote more attention

to parameter estimation and testing model sensitivity; and

. more comprehensive data sampling program

is needed for improved validation, and estimates of model accuracy should be developed

and provided.

Model Standardization

Various suggestions were given for Federal actions to standardize the modeling process:

●

●

●

●

develop standard procedures for model use

(e.g., for determining wasteload allocations);

develop standard procedures for model calibration;

establish guidelines to govern technical development of models; and

coordinate Federal data collection efforts to

assure standardization and quality control.

When models and model use procedures are not

standardized, discrepancies can result if different

models are used for the same purpose. One respondent noted that several State and Federal agencies use different models to analyze the same problem—e. g., setting discharge standards. Coordination is needed to avoid conflicting results.

Funding

Many respondents reported that low funding levels limit State modeling efforts. A few States reported that models were not used at all due to low

funding. States generally use available funds for

adapting existing models (mainly Federal), and

have little or no funds available to develop models

independently. Several respondents suggested that

coordinated Federal-State modeling efforts might

improve the cost effectiveness of modeling.

The respondents also reported that funds are

needed for:

● computer equipment;

● testing and validating models;

● data collection; and

● personnel and training.

Model Maintenance

From the States’ perspective, model maintenance

is a minor problem. As most of the models they

use are federally built, they rely primarily on

Federal agencies to maintain them. States generally

seek assurance that Federal agencies will maintain

the models they have developed, and will advise

States of revisions and modifications.

A few respondents suggested funding States to

maintain needed models if Federal agencies are unable to do so. One State cited intermittent funding for model maintenance as a problem. Several

respondents recommended seminars as an effective

means of informing States of model revisions or

modifications.

Documentation

Few respondents reported problems with inadequate model documentation. The few that did typically made a general comment, citing poor documentation as ‘‘a barrier to model use.

Specific comments included:

●

●

●

user’s manuals are not written for the average

user;

documentation is not provided for modifications in models; and

lack of documentation leads to uncertainty

about the validity of model results.
—.

108 Use of Models for Water Resources Management, Planning, and Policy

STATE MODEL USE IN INDIVIDUAL

WATER RESOURCE ISSUES

Surface Water Flow and

Supply Issues

Flood Forecasting and Control

Flood forecasting and control models are widely used by State agencies. Most States that indicated

a need for flood forecasting models (57 percent of

respondents) currently use them for both operations

and management decisions (43 percent) and planning and policy (45 percent). Some additional States

rely on Federal agency modeling efforts to supply

information needs in this area.

Major uses reported for these models include:

1) delineation of flood-prone areas and estimates

of potential flood-related damage; 2) evaluation of

existing spillway and dam adequacy (under the National Dam Safety Program); and 3) planning/design and operation of flood control facilities. Increased emphasis on nonstructural flood control—

e.g., improved flood plain management—in State

flood control strategies has made models that

delineate flood plains and evaluate the impacts of

land-use changes on flooding patterns increasingly important to State efforts. A number of States

reported a need for flood forecasting and control

models that can analyze small watersheds.

Federally developed models for flood forecasting

and control are widely available to the States. Those

most frequently mentioned in survey responses

were flood control models developed by the Soil

Conservation Service and a series of models

developed by HEC. The effectiveness of the Corps

of Engineers’ training program for these models

has been a major factor in promoting their use at

the State level.

Results from the OTA survey of Federal agencies indicated that model-based information on

flood forecasting and control is distributed to State

authorities by the National Oceanic and Atmospheric Administration, USGS, and the Federal

Emergency Management Agency.

Photo credit: @ Ted Spiegel, 1982

Ruins of an apartment building in Johnstown, Pa., testify

to the destructive power of raging floodwaters. State

agencies widely use flood forecasting and control

models to assess the probable extent of flood

inundations and to route flows in ways that minimize

actual flood damages
Ch. 5—Use of Mode/s by State Governments ● 109

Drought and Low-Flow Forecasting

Slightly fewer than half of the States use models

for forecasting droughts and low flows, but many

States acknowledged that models could be used

more extensively. Forty-seven percent of the respondents saw potential applications in operations

and management, and 63 percent in planning and

policy —the highest reported for any surface water

flow issue area. States in every region of the Nation are concerned with drought and low-flow conditions. While Western States reported use or potential use of these models to allocate water and

estimate the capability to meet demands, the significance of flow to water quality and wasteload allocations has expanded the potential use of models

throughout the country. Eastern States, in particular, emphasized wasteload allocation in discussing

potential applications for low-flow models.

A number of Federal agencies provide appropriate models for State use—respondents identified

those of the Corps of Engineers, the National

Weather Service, and the Soil Conservation Service. Federal agencies also supply States with modelgenerated information—several States mentioned

USGS in this connection. In addition, the National

Weather Service provides low-flow forecasting for

the States.

Streamflow Regulation

Models for streamflow regulation are currently

used by more than half of the survey respondents;

approximately the same percentage of States identified potential uses for these models. The State

survey showed greater present use of streamflow

regulation models than for any other surface

water flow issue. The survey also suggested that

these models are now employed by most of the

States where officials have identified some use

potential.

Respondents identified a broad spectrum of applications for such models, including inter- and

intra-State water distribution, reservoir operations

and dam safety, low-flow effects on wetlands, waste

assiznihtion capacity, flood plain management/

flood insurance, and fishery management below

dams.

Offstream Use

In many areas of the country, current streamflows and ground water reserves are insufficient to

sustain the large withdrawals required for agricultural, industrial, and domestic uses. Projected

growth in offstream demand for mining and general

economic development will increase conflicts between instream and water quality requirements on

one hand, and offstream withdrawals on the other.

Few States currently use models to analyze offstream uses. Those that do, concentrate on planning and policy for projecting future use. Only one

State specifically mentioned planning, managing,

and operating offstream facilities as an area presently involving the use of models. However, nearly

half of the surveyed State officials indicated potential use for offstream models. Determining the availability of water for hydropower, mining, and industrial uses was considered a future area for model

use, particularly in the context of comprehensive

resource management. Eastern States as well as

Western States were concerned with offstream uses.

Irrigated Agriculture

Increasing conflicts with domestic water supply

and instream flow needs necessitate sophisticated

planning and monitoring to ensure maximum benefits from irrigation water. State agencies employ

models to determine current and future supplies

and demands, and to determine optimal irrigation

schedules to aid farmers in conserving water. Such

models are currently used in about one-fifth of the

surveyed States; slightly over twice as many States

reported a potential for model use. Potential uses

include assessing both quantity and quality of surface water, as well as the effects of irrigation on

ground water levels. Future uses for irrigated agriculture models include determining water rights,

water demands, and stream diversion.

Domestic Water Supply

Domestic water supplies have not kept pace with

growing demands. In many localities, supply, treatment, and distribution systems are inadequate, resulting in shortages and reduced water quaiity.

Comprehensive management for conservation, and
110 . Use of Models for Water Resources Management, Planning, and Policy

multiple-objective planning, will become increasingly necessary as further growth occurs in watersport areas.

Current use of models by States focuses on projecting present and future supplies and demands,

and designing supply systems to meet futur~ demands. Slightly under one-third of those surveyed

use water supply models. Approximately twice as

many indicated potential for model use, primarily

for assessing the relationship between water supplies and water quality requirements. A few States

indicated a need for models to analyze the efficiency

of existing distribution systems.

Instream Flow Needs

Models for assessing instream flow needs serve

a variety of purposes at the State level. Their use

in planning and policy to meet instream flow needs

for fisheries, recreation, and hydropower was

reported by 37 percent of the States—an additional

24 percent indicated the potential for such use.

Fifty-five percent of the States acknowledged a

potential need for operations and management

models, although only 12 percent currently use such

models.

Instream flow models are becoming increasingly important as tools for setting minimum instream

flow requirements. The models have further application for meeting water quality standards and allocating water. A few States cited data limitations as

constraints to current use. Assistance in using these

models is supplied by the Fish and Wildlife Service’s 1nstream Flow Group, the Corps of Engineers,

and USGS.

Water Use Efficiency and Conservation

Little is currently known about the extent to

which demands for water could be reduced through

the use of conservation techniques or improved

management and planning. However, potential

benefits in reduced expenditures for supply, treatment, and distribution systems were sufficient for

one-fourth of the States to indicate a potential use

for models in researching these problems. This represents the greatest State interest in models for

research purposes among all surf’ace water resource

issues.

Under 20 percent of the States surveyed currently

use models in this area, although close to half indicated potential uses for such models. State use focuses on models for predicting demand, and basic

water accounting models similar to those used in

determining available supplies for agricultural,

domestic, and other offstream and instream uses.

Greater existing and potential use was reported for

planning and policy purposes than for operations

and management.

Surface

Urban Runoff

State officials

Water

reported

Quality Issues

high potential for model

use to determine water quality problems stemmin,q

from urban runoff, despite low levels of current use:

Two-thirds of the States saw continuing or possible future uses for such models in planning and

policy analyses, and 55 percent envisioned uses for

operations and management decisions. Several

States suggested that the credibility of existing

models has limited their use.

The comprehensive planning provisions of section 208 of the Clean Water Act figure largely in

State reports of existing and potential uses for urban runoff models. Models are currently used to

develop control measures; to plan, construct, and

maintain storm overflow facilities; and to research

and predict local urban runoff problems. Problems

of site-specific adaptability and excessive complexity

in current models were mentioned by a number of

respondents. Respondents indicated that simple

models for site-specific calculations could increase

model use in this area, even though such models

may not be suitable for complex runoff problems.

Erosion/Sedimentation

A number of States indicated the need for improved erosion/sedimentation models as a priority

in water resource management. Of the State respondents, 53 and 69 percent saw potential uses

for these models in operations/management and

planning/policy, respectively—approximately 2

times the current level of use.

Many States reported current and potential model use under section 208 of the Clean Water Act.
USGS and the Soil Conservation Service were repeatedly cited as providing models or working jointly with States to determine erosion and sedimentation effects.

State officials reported a wide variety of potential uses for erosion/sedimentation models; among

these are evaluating erosion control measures, determining canal and reservoir sedimentation rates,

evaluating irrigated and nonirrigated agricultural

land uses, and planning for urban development.

Salinity

Salinity models do not appear to have a high priority in State-level water resource management.

Less than half the State respondents identified potential uses for such models, and only 6 percent currently use them for operations and management

decisions. Potential uses include: 1) determining

the ecological benefits of salinity reduction;

2) implementing State ground water laws;

3) monitoring effects of pesticides and residuals; and

4) monitoring inland streams receiving brines from

saltwater sources.

Agricultural Runoff

One-third of the States currently use agricultural

runoff models for planning and policy, and nearly

double that figure-57 percent—anticipate potential uses. A number of States use models in connection with section 208 of the Clean Water Act; others

specified future uses in planning and regulation of

animal wastes as well as in developing and implementing fertilizer and pesticide management plans.
112 . Use of Models for Water Resources Management, Planning, and Policy

Concern over the effects of agricultural runoff

is reflected in actual and potential model use

reported by States for research in this area. While

only 8 percent of State respondents presently use

agricultural runoff models for operations and management decisions, 14 percent use them for research, and 27 percent identify future research

potential for such models.

Airborne Pollution

Several of the comments indicated that some respondents misinterpreted this question. These respondents may have identified model use for State

air pollution control, rather than for the specific

purpose of determining the effects of airborne pollution on water quality. However, two States identified potential use of models for acid rain abatement.

Wasteload Allocation

States use models extensively for determining

wasteload allocations. Two-thirds of the State

respondents indicated present use for operations

and management decisions, and 57 percent reported current use in planning and policymaking—

more than for any other water resource-related purpose. Survey responses suggested that the relatively

long history of model use in this area has made these

models widely available to States. Most States that

recognize potential uses for these models are presently using them. The ubiquity of wasteload allocation problems, and the expanded State role in water

pollution control, has contributed to widespread

wasteload allocation model use. Model use was specifically mentioned for implementation of sections

201, 208, 303, and 402 of the Clean Water Act.

Many States, however, stated that these models

need refinement. Further validation of reaction

rates and other necessary parameters, standardization of models for different geographic regions of

the country, and evaluations of the magnitudes of

error in predictions, were among the improvements

suggested. Several States also identified the need

for standard wasteload allocation models for the

following purposes: evaluating the effects of

discharges into nontypical streams (swamps,

estuaries, and intermittent streams), designing

standard waste treatment facilities, and determining the need for advanced waste treatment.

Thermal Pollution

State water resource professionals reported that

available thermal pollution models are simple and

accurate. About one-fourth of the surveyed States

reported current use of such models, and about half

of the respondents recognized potential uses for

them. A number of States noted that all necessary

thermal modeling under section 316(B) of the Clean

Water Act is performed by power-generating or

other industries, and is merely reviewed at the State

level. Others cited the Corps of Engineers, EPA,

and USGS as providing thermal modeling services

for States or in conjunction with State efforts.

Toxic Chemicals

Many States identified the development of models to deal with toxicants as a top priority, with significant potential for future applications. As with

other recently recognized problems, about onefourth of responding States identified a need for

such models in research, although few of the respondents currently use them for any purpose. Potential uses, both for operations/management and

policy/planning, were identified by 55 percent of

the surveyed officials.

Respondents indicated that models are needed

for determining sources of toxicants, toxicant

transport and removal mechanisms, and for setting

toxic chemical effluent standards. Some States identified data availability as a limiting factor in modeling.

Drinking Water Quality

About half the States reported potential uses for

drinking water quality-related models, primarily to

assist in setting standards required under the Safe

Drinking Water Act. States also noted uses for improved models in determining the effects of wastewater discharges on drinking water quality, as well

as for specific problems such as the effects of mining and low flows. A small number of States indicated that these models were of high priority; fewer

than one-fifth of the States indicated that they are

currently used.

Water Quality Impacts on Aquatic Life

Several States stressed the need for further research and improved modeling techniques to gage
Ch. 5—Use of Models by State Governments 113

the effects of changes in water quality on aquatic

life. Credibility problems of current eutrophication

models were specifically mentioned. Survey comments suggested that improvements to aquatic life

impact models are of major concern to respondents

throughout the country.

Sixty-nine percent of surveyed State officials

identified potential application for these models in

planning and policymaking; 55 percent identified

future operations and management uses—in both

cases about twice the existing level of use. Officials

identified a variety of uses for aquatic life impact

models, including evaluating permit applications,

pollution control program planning, and comprehensive basin planning.

Ground Water Issues

Ground Water Supplies and Safe Yields

Over half the surveyed State personnel indicated

use of models for determining ground water supplies and availability—the highest reported ground

water-related model use. Many acknowledged use

of USGS models and modeling expertise in developing ground water modeling programs. As might

be expected, the use of such models by Western

States in determining water rights was mentioned

frequently; however, ground water supply model

use was equally evident for Eastern States.

Ground water supply models are presently employed by most of the States that reported some use

potential; however, many States place a high priority on improving these models. The lack of historical aquifer performance data and the extensive

current data requirements of ground water models

were repeatedly cited as hindering State modeling

efforts.

Conjunctive Use of Ground and Surface Water

A higher percentage of survey respondents reported potential uses for models of the interaction

Photo credits: @ Ted Spiegel, 198.2

Lake Tahoe, Nev., has long been billed as one of the world’s clearest bodies of water. Rapid development along

shorelines, however, has greatly increased the flow of nutrients into the lake, accelerating natura{ eutrophication rates,

creating nuisance algal growths, and endangering Tahoe’s ecological balance. Models have been used both to assess

the effects of development and to evaluate the effectiveness of centralized sewage treatment in preventing the

eutrophication process. In underwater labs above, University of California biologists and hydrological scientists use

radioactive trace elements to monitor nutrient levels in the water. Meanwhile, crews build sewage transport facilities

to divert wastes around Lake Tahoe for treatment and release in less sensitive areas
114 ● Use of Models for Water Resources Management, Planning, and Policy — ———

between ground water and surface water than for

any other ground water-related issue. Such models

are valuable for developing comprehensive basin

plans and for comprehensive water supply management. Over 35 percent of the surveyed States currently employ conjunctive use models—after supply

and safe-yield models, they are the most extensively

used model for ground water management. Some

States reported using models developed by USGS;

a number of others observed that the lack of field

data constitutes a bottleneck to using these models.

Accidental Contamination of Ground Water

Although over half the States indicated potential for future use of models that predict the spread

of contaminants in ground water, fewer than 10

percent currently employ them. Gaps in current

knowledge about the behavior of contaminants in

some types of ground water systems and data limitations upon the construction and validation of such

models hinder more widespread use. Survey respondents envisioned such future applications as

determining effects of various pollutants and

requirements for control measures, devising warning systems for the public, and predicting longer

term contamination.

Agricultural Pollution to Ground Water

Determining the effects of agricultural pollutants

on ground water is also a modeling area where reported potential for State-level use is high, although

a low percentage of States currently use models.

Seventy-one percent of the surveyed State officials

saw potential uses for such models in planning and

policymaking, and 57 percent envisioned operations

and management uses—current uses amount to less

than one-sixth of these potential use levels. The officials specified potential uses for these models in

section 208 planning, determining effects of various

contaminants and corrective measures, planning “1-l

allowable point source pollutant loads, and supplemental monitoring for regulatory purposes. A number of States indicated that data on pollutant movement is a limiting factor in model development and

use.

Ground Water Pollution From Waste Disposal

Survey respondents indicated that lack of data

and poor understanding of ground water chemistry

are primary limitations on States’ abilities to model

the spread and effects of pollutants to ground water

from waste disposal sites. Limited understanding

of the reactions and diffusion of pollutants in mixed

geological formations, and deficiencies of data for

validation purposes, were cited as specific problems.

While potential uses were reported by a high proportion of State officials-71 percent for planning

and policymaking, 59 percent for operations and

management decisions—these models are currently

used by only one-fifth as many States. Anticipated

uses include determining infiltration from sanitary

landfills and mine waste disposal.

Saltwater Intrusion

Several States indicated that models for determining saltwater intrusion to ground water supplies

are water resource management priorities; however, interest is naturally limited to coastal areas

and States with major inland saltwater bodies.

The acquisition of sufficient data to verify such

models was repeatedly cited as a significant need.

State officials envisioned several management uses

for these models, in particular establishing recharge

areas, as well as determining acceptable pumping

rates and designing well fields.

Economic and Social Issues

Effects of Pricing on Use

Models that evaluate the effects of pricing on

water use were seen as having potential planning

and policymaking uses by 59 percent of the State

survey respondents. Respondents referred to comprehensive planning efforts under title III of the

Water Resources Planning Act and section 201 facilities planning under the Clean Water Act as areas

in which models are needed. Some States suggested

that current models are not precise evaluation tools,

and that their importance may be limited to places

where strict conservation and reuse laws apply.

Models are currently used by a small proportion

of surveyed States, primarily in planning and research.

Costs of Pollution Control

Slightly fewer States indicated a need for models

to evaluate pollution control costs than for most

other types of social and economic modeling. Su~-
Ch. 5—Use of Models by State Governments . 115

gested potential uses include assessing the effects

of alternative waste treatment strategies on firm

behavior, and determining the impacts of pollution

control costs on individual industries. At present,

such models are used in only a few States.

Cost/Benefit Analysis

Use of cost/benefit analysis models for planning

and policymaking was envisioned by over half the

State officials; 23 percent of those surveyed currently use such models for planning. Some current users

noted, however, that models evaluating the cost effectiveness of alternative actions are more applicable

than cost/benefit models. Several respondents consider the cost/benefit concept too subjective to be

adequately modeled. A number of States indicated

that improved models for cost/benefit analysis

would be highly desirable, and one respondent specified a need for a combined hydrologic/economic

model for cost/benefit studies.

Regional Economic Development Implications

Models for evaluating economic implications of

water resources development and policy are used

by States in the context of planning efforts under

section 208 of the Clean Water Act and title III of

the Water Resources Planning Act. Slightly fewer

than one-half of the surveyed State personnel predicted future uses for these models; 22 percent indicated current planning uses. Officials mentioned
. —

116 ● Use of Models for Water Resources Management, Planning, and Policy

such specific uses as predicting population and

economic growth in water-short areas, comprehensive river basin planning, and determining the effects of ground water depletion.

Forecasting Water Use

Forecasting water use with models was considered possible at the State level by 59 percent of

survey respondents; 31 percent currently use such

models for planning and policy purposes. Some

States doubt the reliability of these models in their

current forms, and suggested that existing data are

inadequate to justify sophisticated model forecasting. A variety of applications are projected for

improved models; ensuring that water quality

standards are not violated due to overallocation of

supplies, and evaluating existing laws regulating

ground and surface water use were repeatedly mentioned, as well as simple projections of future

demand.

Social Impact

Relatively few States indicated a need or potential use for social impact models. While one State

official suggested development of a general model

that could be calibrated to local conditions, little

State-level interest in such models was expressed,

and some respondents questioned their reliability.

Risk/Benefit Analysis

State officials reported a variety of potential uses

for risk/benefit analysis models, including dam safety analysis, flood management, and toxic waste

management. Slightly fewer than half foresaw future planning and policy uses for these models in

their States; 10 percent currently employ them.

Competitive Water Use

Fifty-nine percent of the surveyed officials indicated the possibility of future planning and policymaking applications for models of competitive water

use; one-fifth reported that such models are currently used by their States. A few States reported

that these models are a high priority for analytical

work. Reported potential applications include:

basinwide water supply planning, water rights determinations, and the evaluation of conflicts between water supply and water quality objectives.

Unified River Basin Management

Models for unified river basin management are

currently used by a greater percentage of States

than any other socioeconomic model: one-third of

the survey respondents indicated that such models

are currently employed for planning and policymaking, and nearly twice as many foresaw future

use potential. State-level personnel mentioned such

uses for these models as regional water supply planning, integrating water quality considerations with

basin development, planning studies to evaluate different management options, and planning and control of development.
Chapter 6

Modeling and Water Resource Issues
Contents

Page

Surface Water Flow and Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

Types of Models Used in Surface Water Flow and Supply Analysis . . . . . . . . . . . . 121

Water Availability Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

Water Use Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

Evaluation of Currently Available Surface Water Flow and Supply Models . . . . . 130

Surface Water Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

Types of Models Used in Surface Water Quality Analysis . . . . . . . . . . . . . . . . . . . . 132

Nonpoint Source Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134

Point Source and General Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

Evaluation of Currently Available Surface Water Quality Models . . . . . . . . . . . . . 141

Ground Water Quantity and Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

Types of Models Used in Ground Water Resources Analysis . . . . . . . . . . . . . . . . . 144

Ground Water Quantity Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

Ground Water Quality Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

Evaluation of Currently Available Ground Water Models . . . . . . . . . . . . . . . . . . . . 151

Economic and Social Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

Basic Analytical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

Types of Models Used for Economic Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

Other Social and Economic Analytical Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . 155

Economic and Social Issues in Water Resource Analysis . . . . . . . . . . . . . . . . . . . . . 156

TABLES

Table No. Page

7. Surface Water Flow and Supply Model Evaluation . . . . . . . . . . . . . . . . . . . . . . . . 130

8. Surface Water Quality Model Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142

9. Ground Water Model Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Chapter 6

Modeling and Water Resource Issues —— —— —

Government agencies normally use water resource models to address specific resource problems

under their jurisdiction. While most problems and

model applications have unique aspects, it is possible to generalize about the kinds of problems most

frequently encountered in water resource managemerit — and the analytic techniques used to understand them. This chapter describes 33 of the Nation’s most prevalent water resource issues, briefly assesses the modeling capabilities associated with

each of them, and evaluates the model types used

to analyze them. Previous chapters have focused

on generic issues and problems involving water resource models; this chapter deals with specific water

resource concerns and the capacity of models to address them. It is provided as a layman’s introduction to the relationship between models and realworld water resource issues.

Water resource concerns can readily be grouped

according to four major subject areas: 1 ) surface

water flow and supply; 2) surface water quality;

3) ground water quantity and quality; and 4) eco

nomic and social models. The areas differ significantly with regard to levels of current knowledge,

kinds of issues addressed, and types of models and

levels of modeling expertise currently available.

Each is discussed in a separate section of the

chapter.

The first three subject areas deal primarily with

physical processes, and are described according to

a common format: 1) introduction; 2) types of models; 3) issues addressed; and 4) evaluation of currently available models. Each subject-area model

evaluation follows a format that reflects the problems addressed, processes modeled, and mathematical techniques most commonly used within

each scientific discipline. The last area, economic

and social models, deals with the social science information needed to support water resource decisionmaking. Models of social sciences processes differ fundamentally from those of physical processes,

and are extremely diverse; consequently, a larger

subjective component is involved in evaluating

them. No formal evaluation of economic and social

models was undertaken for this study.

SURFACE WATER FLOW AND SUPPLY

Introduction

Managing surface water today virtually requires

the use of a wide range of computer-based analytical

techniques, ranging from sophisticated models that

forecast the probable frequencies and extents of

serious floods, to relatively simple computer models

for simulating the operational characteristics of farm

irrigation systems. All of these models provide information to help assure that water will be available

when and where needed, or will not intrude when

or where it is not wanted. Models permit the analyst

to: 1 ) make reasonable predictiom of natural events,

and 2) estimate the favorable and adverse cosequences of man’s attempts to improve the reliability of’ freshwater production, distribution, and use

Syst ems.

Water resource models are widely applicable to

problems in policy, planning, operational management, and regulation of the Nation surface water

resources. Existing models are widely used to plan

and operational~ manage most water availability y and

water use problems. Model use is not as common

for policy and regulatory activities, partially because

existing models are not well adapted to decisionmaking in these governmental areas, and partially because such decisions have traditionally been

based more on qualitative than quantitative criteria.

Models used to analyze surface water flow and

Supply problems can be subdivided into two broad

categories, for which both current model capabilities

and future promising roles are somewhat different.

For each of the two broad categories-water avail119
120 ● Use of Models for Water Resources Management, Planning, and Policy

ability and water use—four specific problem areas

are discussed later in this section. Although these

problem areas are not all-inclusive, they encompass the major surface water quantity problems facing the Nation. Each problem area is specific

enough to permit discussion of successes and failures in the use of models, and development of recommendations for appropriate model uses. An evaluation table for the models used in each problem

area is presented later in this chapter (see table 7).

To introduce the modeling techniques that apply to surface water flow and supply issues, applicable model types are discussed below. Generally,

the model types are not limited to one specific problem area—each model type may be applicable to

several issues. References, keyed to over 30 model

classes, are provided in appendix D to this report.

Availability of Water

Water availability analysis-which encompasses

but is not limited to the sciences of hydrology and

meteorology —uses models extensively. While models are less frequently used in policymaking than

for planning and management, numerous examples

of model use for determining water availability can

be cited throughout private industry and at all levels

of government. In fact, a major problem in using

models to analyze a given water availability problem is the difficulty of selecting—from among the

plethora of available models—the most appropriate

model for the problem at hand.

Determining the availability of surface water requires analyses of the hydrologic cycle, typically including calculations of streamflow magnitude, duration, and frequency; and the temporal and spatial

variations of these streamflow characteristics. A

specific problem may require analyzing one or more

of these characteristics at a single point along a

stream—for instance, to determine the extent of a

flood plain—or it may require coordinated analysis

at a large number of locations in a watershed (e. g.,

to operate a series of multiple-purpose reservoirs).

Solving problems of water availability, however,

requires more than understanding and modeling

the hydrologic cycle. Many problems arise because

of the need to alter natural hydrologic processes for a

variety of reasons: to reduce flood hazards; to

reduce the risks of drought and low streamflow; to

change the timing and distribution of streamflow;

and to improve management of this increasingly

scarce renewable resource for a variety of beneficial

purposes. Certain types of human intervention in

natural hydrologic processes can be modeled reasonably well, but many types of modifications and

controls introduce conditions that may be too complex to simulate or forecast accurately. In dealing

with water availability problems, one must distinguish between the capability to model natural proc-
Ch. 6—Modeling and Water Resource Issues ● 121

— —

esses, and current capabilities to model the effects of

human management efforts on these processes.

Water Use

Models have been used less frequently to analyze

water use than to analyze water availability. Except for agricultural irrigation needs in arid areas

of the Western United States, water availability has

historically been so much greater than water use

that there was little or no requirement for sophisticated analysis. Consequently, almost no effort was

expended on developing models to analyze water

use. In recent years, however, increasing demand

for relatively large quantities of water—e. g., for

energy development—and the droughts of the

1960’s in the Northeast and the 1970’s in the

Midwest and West, have stimulated the development of models for planning and operations/management. Nonetheless, these recent developments

are not yet reflected in widespread adoption of water

use models.

Water availability and water use also differ in

the kinds of information they require for model construction. Most problems of water availability are

concerned with physical principles and relationships

that are reasonably well understood, and are consequently easier to model successfully, while most

water use problems involve not only physical factors but also social and economic factors—many of

which are less well understood. The lack of knowledge about interrelationships among economic, social, and physical factors is compounded by a lack

of data on social and economic factors related to

water use. Social and economic models are discussed in more detail later in this chapter.

Types of Models Used in Surface

Water Flow and Supply Analysis

Of the wide array of models used to analyze various aspects of surface water flow and supply, the

most important ones fall into two broad model

classes—process models and statistical models. Process models simulate or describe the flow of water

through a watershed or water body using known,

physical relationships. Statistical models use empirically derived relationships—often with no inherent

physical meaning—to estimate the probability of

a flood or drought, the magnitude of a flood peak,

or even regional water use demands.

Watershed Process Models

Watershed process models follow the movement

of water from the time it reaches the Earth as precipitation until it flows into a lake or stream, reaches

a ground water aquifer, or evaporates back to the

atmosphere. Models used to describe the dynamics

of water over three distinctly different types of land

areas are described in this section: 1) watershed

simulation models, which describe the movement

of water over large, nonurban areas; 2) agricultural

soil/water interaction models, which are designed

to specifically address agricultural water problems;

and 3) urban runoff models, which describe the

movement of water through urban areas.

Watershed Simulation Models.—Simulation

models describing the movement of water over

large, nonurban areas are used to estimate flood

peaks, low flows, and volumes of water available

to users. They are most useful where historical

streamflow data are sparse or nonexistent. These

simulation models are powerful planning tools that

come far closer to replicating measured flows than

was previously possible. Four types of processes

must be included in watershed simulation models:

1) the movement of rainfall into and through the

soil; 2) ground water flow to streams (called baseflow); s) the l0SS of water to the atmosphere from

evaporation and evapotranspiration from plants;

and 4) in colder climates, snow accumulation and

snowmelt.

Watershed soil/water process models are used to replicate water movement into and through the soil for:

1) estimating flood peaks during storm events;

2) estimating water supply on an annual basis; and

3) estimating low flows during dry periods. Current models are most reliable for estimating low

flows and total annual runoff volumes, and less so

(but still acceptable) for calculating short-term flows

and flood peaks.

During low-flow periods, except in very humid

climates, water enters streams primarily by seepage

through the soil profile or from aquifers. Most

baseflow models do not use advanced ground water

modeling techniques to estimate flow rates, but

8 + - [ 83 n - 82 - 3
122 ● Use of Models for Water Resources Management, Planning, and Policy

rather use observed flow patterns during long dry

periods as an estimate of ground water flow to

streams. They are quite adequate for estimating

baseflow during floods, and reasonably good for

estimating low flows.

Evaporation from water surfaces and evapotransPiration from plants are modeled to simulate the soildrying process. The drier the soil, the more precipitation will infiltrate and be stored during the next

storm. The results are more reliable for watershedwide average soil moisture than for specific locations within the watershed, but are difficult to validate because of the scarcity of field data.

For areas where snow remains on the ground for

more than about a month, the processes of snow

accumulation on the ground and snowmelt in the

spring must also be considered. Total runoff volumes from snowmelt can be simulated quite well

for forecasting water availability during the following summer, but models are not very reliable for

simulating snowmelt flood peaks (magnitudes are

bad and timing is worse), because of the difficulty

of predicting spring weather conditions. However,

in areas where the snowmelt occurs relatively slowly, the models are adequate for most purposes.

Agricultural Soil/Water Interaction Models.—

Simulation models similar to the watershed process

models described above have been developed to

assist in agricultural water conservation. Four types

of models are currently available:

Soil/water process models are sometimes specialized to estimate moisture conditions in a small

plot, rather than average conditions over an entire

watershed. These P!ot--size soil/water process models are

used for agricultural water management and landuse decisionmaking. This approach has potential

for improving crop management decisions, but

these models are not yet very accurate.

Models that analyze the effects of local climatic

variation on @ant water use are valuable for allocating

available water supplies. Acceptable results are obtained on an annual or seasonal basis, but estimates

of shorter term demands (less than 1 month) are

unreliable.

The extent and duration of the soil’s capacity to

hold irrigation water for plant use has been modeled

to assist in farm water management and irrigation

system design. Results from irrigation water demand

models are generally reliable for estimating average

annual water use, but poor for estimating how use

is distributed over the irrigation season.

In areas where excess water is a problem, soil

moisture can be reduced by subsurface tile or ditch

drains to make the land more productive. Land

drainage models estimate flow rates for system design

and residual field moisture conditions for cropping

decisions. These models achieve adequate to good

results.
Ch. 6—Modeling and Water Resource Issues ● 123

Urban Runoff Models .—Urban runoff models

generate simultaneous flows from many small urban watersheds, and aggregate them into flood

flows for specified downstream points. These models are sophisticated tools for urban flood plain

management and for designing and operating

urban storm-water control systems. They have received widespread use over the last few years and

promise a great deal for the future.

Stream Process Models

Stream process models begin describing the

movement of water at the point where watershed

process models end—once the water enters a

stream, lake, or reservoir. In this section, two topics

are discussed: 1) models that describe the flow of

water through streams, lakes, and reservoirs, used

primarily for flood control; and 2) models that describe the movement and erosion of sediments

(called alluvial processes) within water bodies.

Channel Process Models.—Channel process

models describe the flow of water through streams,

lakes, and reservoirs. They are often used for reservoir operations during flood conditions and for flood

plain management. In general, they provide very

reliable results when accurate information on channel and flood plain geometry is available. The following models are included in this category:

F[ood channel routing models are used for operating

flood control facilities or issuing warnings during

flood emergencies. These models provide quite reliable estimates of changes in flow depth and velocity as water moves downstream in well-defined

channels. However, the estimates are less accurate

for larger floods where streams overflow their

banks, and are particularly unreliable where flows

spread out over large flat areas.

When flows enter a lake or reservoir they increase

both water depth and outflow through spillways or

other outlet controls. Lake and reservoir routing models are accurate enough to size spillways to ensure

dam safety and for controlling spillway gates to minimize downstream flood damage.

Flood plain management relies heavily on accurate mapping of flood hazard areas. Models can

estimate flood heights and—when combinecl with

accurate topographic maps—the geographic extent

of flooding. The most accurate results from flood

inundation models are achieved when the stream flows

between stable channel banks, and the least reliable

estimates are obtained on broad flat flood plains

where flows are deflected by small obstructions and

are spread in random patterns from one event to

the next.

Special channel routing models are used to determine the downstream areas that would be inundated if a dam failed. The reliability of dam failure

models is uncertain, because few historical records

are available on the hydrologic conditions existing

at the time of failure.

Alluvial Process Models. —The dynamics of

channel erosion and sediment deposition have been

described through modeling techniques. The results, however, are approximate, and a great deal

more research is needed to make these models reliable. Two important problem areas include reservoir sedimentation and channel erosion:

Re.sewoir sedimentation models have been developed

for determining the amount of sediment washed

into a reservoir that is deposited on the bottom, thus

reducing its water storage capacity. These models

do not have the accuracy desired for estimating

useful reservoir life, unless supported by empirical

relationships from reservoir surveys.

Flowing water can erode the channels through

which it flows and deposit sediment loads downstream. Problem locations can be identified by

using channel erosion and deposition models, but the

results are not reliable enough for channel design

or maintenance management.

Statistical Models

When causative mechanisms are not well enough

understood to construct process models, or the expense of developing or using process models is not

justifiable, statistical models are often used in their

place. Statistical models can be used whenever

enough data are available to estimate the relationships between factors of interest—without having

to understand the underlying physical processes.

Three types of models are presented in this section: 1) statistical flood models, which yield results

similar to combined watershed and stream process
124 Use of Models for Water Resources Management, P/arming, and Policy

-— —.— . .

models; 2) flood and drought frequency analysis,

used for sizing flood control or water supply projects; and 3) water use statistical relationships, which

are used to estimate demands for water.

Statistical Flood Models .—Statistical models—

simpler in approach than the process models discussed earlier—have been developed to estimate

flood flows and areas of inundation. These tools are

useful for structural design or reservoir operation

in situations where more sophisticated continuous

simulation models are not justified. Three common

approaches—flood formulae, regional flood formulae, and unit hydrography models—have been

extensively used.

Flood formulae are simple equations for estimating

flood peaks from watershed characteristics. They

have been used for years to help design small structures, but can only be recommended for relatively

small projects. Much more reliable for structural

planning are regional flood formulcw. These equations

are derived statistically using historical data and

can be used for estimating flood peaks on streams

throughout hydrologically uniform regions.

Another approach, called unit hydrography mode/-

ing, is based on the assumption that a given amount

of runoff from a given watershed will always result

in similar flood patterns. These models have long

been used to establish flow patterns for designing

flood control reservoirs. The results are reasonable

for reservoir design to prevent flooding by a storm

event of specified size, but less than desirable for

reservoir operation.

Flood and Drought Frequency Analysis.—

Several approaches are available for estimating the

frequency of occurrence of floods and droughts. The

purpose of these models is to determine the economically optimal size of flood control or water supply

projects. The available statistical models provide

reasonable to good results for most applications.

Flow frequency models analyze historical series of

flood peaks, flood volumes, or low flows to provide

an estimate of the maximum or minimum flow

magnitudes to be expected, on the average, no more

than once every 10 years, 100 years, or some other

period. The reliability of these models improves

with longer record lengths. Once the statistical characteristics of streamflow have been determined, annual data generation models can generate annual runoff

sequences that match the size, probability distribution, and other patterns of historical flows for use

in determining reservoir capacity. The results are

generally good for monthly, seasonal, or annual

time periods.

Another important use of statistical models is for

assisting reservoir design. By accounting for all inflows (stream and precipitation) and outflows (evaporation, uncontrolled releases, and project water

delivered) over long time periods, capacity requirements for designing reservoirs and rules for operating them during dry periods can be determined.

Reseruoir water accounting models provide excellent results if reliable data are available to describe inflow

and storage volumes.

Water Use Statistical Relationships.—Water

use demands (use as it would be if unconstrained

by supply shortages) are estimated either from historical data or simulation models. Two types of

models have been applied on broad regional scales:

Regional water use relationships statistically estimate

peak, annual, and seasonal variations in water use

rates. Their results are generally adequate for estimating the volume of water needed over long periods, but not for estimating peak demands.

Annual use generation models, similar to models that

simulate streamflow, have potential for generating

estimates of monthly to annual water use. These

results may then be combined with supply estimates

for the same period to improve water supply reservoir design or operating procedures. However, reliable models of this type are not widely used.

Water Availability Issues

Flood Forecasting and Control

Floods rank among the most prevalent of natural

hazards. About half of the Nation’s communities,

and nearly 90 percent of its largest metropolitan

areas, are located in flood-prone areas. Despite expenditures of more than $13 billion for flood control over the last 50 years, flood damage continues

to rise each year. Residential, commercial, and industrial development in flood-prone areas outstrips

our ability to provide protection, while the economic value of existing damage-susceptible property increases as well.
Ch. 6—Modeling and Water Resource Issues ● 125

Available models and the hydrologic data required to operate them are generally adequate for

flood control planning and management. Even in

situations where hydrologic records are not as extensive as designers require, statistical methods and

digital simulation models provide sufficient information for designing flood control and protection

structures.

Although there are isolated cases of design deficiencies in flood control projects, most of the hundreds of existing projects function as planned.

When flood damage occurs in ‘‘protected’ areas,

it is generally not due to faulty flood forecasting

or to failure to operate flood control projects properly. Rather, damages occur because the flood magnitude exceeds the degree of protection provided

by the project. However, when flood magnitudes

exceed the project’s protective capabilities, accurate

forecasting becomes essential for minimizing loss

even if it cannot prevent loss. A poor forecast of a

flood exceeding the control structure’s capacity can

cause serious mismanagement, and greatly increase

the resulting damage. Improvement is needed in

the accuracy with which flood characteristics are

predicted once the event is under way.

While models and predictive methods for flood

control planning and management are generally

satisfactory for design, engineering, and routine

operation of traditional areawide flood control structures, flood control planners are increasingly concerned with nonstructural measures for reducing

flood damage. Consequently, new needs for models

and data aimed at nonstructural approaches have

arisen. Many of these measures are regulatory in

nature, and frequently address areas considerably

smaller than those associated with larger scale structural projects. As a result, many traditional flood

control models are not suited for planning and managing nonstructural approaches. These traditional

models are based on a ‘‘ macrohydrologic’ scale,

in which model assumptions and data requirements

are scaled to hydrologic analyses for relatively large

watersheds. However, when these models are applied to the ‘‘ microhydrologic’ scale, they are often

fuuncl to be inappropriate, either because detailed

data are not available at the microscale level, or

because the macroscale assumptions are not consistent with conditions on the smaller scale.

Good hydrologic analysis on a microscale basis

requires considerably more data than macroscale

analysis; consequently, geographic consistency in

data on soil types, vegetation, land use, precipitation, and surface runoff is considerably more important in microscale analysis. As a result, the models

being developed for microscale analysis frequently depend on the availability of spatial data bases—

i.e. , sets of computerized ‘‘maps’ with a geographically consistent set of data on an area’s physical characteristics. Although the needed data are

frequently available on printed maps, the effort required for digitizing and maintaining the data significantly limits widespread use of these models at

present.

Model use for the regulatory aspects of flood control has been extensive in both flood plain management and flood insurance programs. Two basic

types of models—flood inundation models and flood

frequency models—have been widely employed.

Flood inundation models are used to delineate flood

hazard areas. When properly used, the available

models are relatively noncontroversial. However,

problems have occurred when the analysis is performed for part of a stream at one time and for adjacent parts at another time, with the result that

the flood hazard areas fail to coincide at the boundaries of adjacent areas. Since the primary purpose

of this analysis is regulatory in nature—identifying

areas subject to flooding so that appropriate restrictions in use can be implemented—it is not surprising that even minor inconsistencies in flood hazard

area delineations are major sources of controversy.

A larger source of controversy has been the use

of statistical flood models to determine the magnitude of flood associated with a specified recurrence

interval (usually 100 years). Each of the half dozen

or so major flood frequency theories (and the models based on them) produces somewhat different results in a given setting, even when the same data

set is used for all cases. In some instances the different theories give considerably different results,

so that estimates of the size of a 100-year flood, for

instance, may vary by a factor of two or more. With

that large a variation in flood magnitude, there is

an attendant, but usually somewhat smaller, variation in flood hazard area—since the amount of land

subject to development restrictions varies with the
126 Use of Models for Water Resources Management, P/arming, and Policy

estimate of the 100-year flood magnitude. Flood

frequency estimates at different points on the same

stream using different models (or even at the same

point using different models) often produce different

results, causing a tremendous amount of confusion

and controversy. Since the differences are not due

to error in calculation, but to fundamental differences in the assumptions of the models, the differences are essentially irreconcilable. The need for

consistency was a major factor in the Water Resources Council’s decision to recommend a uniform

technique (or model) for use by Federal agencies

in performing flood frequency analyses. That decision has eliminated some, but not all, of the controversy.

LOW-FlOW and Drought Forecasting

Low streamflow is caused primarily by physical

phenomena, while droughts result from the joint

occurrence of low streamflow and high demand—a

condition due to social and economic causes as well

as physical ones. Modeling capability for forecasting

and managing low streamflow per se is as highly

developed as for flood forecasting. However, from

the point of view of drought management, which

requires an ability to modify both water availability

and water use, the available models are less satisfactory.

The major difficulty in forecasting low flows

stems from problems in choosing appropriate statistical procedures for determining how often to expect low flows of a specified volume and duration.

Most of the theories used in hydrologic probability

analysis are based on the concept of independence—the idea that two or more “events’ are totally unrelated to one another. In the case of low

streamflow, analysts are normally concerned with

the quantity of streamflow during a specific period

of time. Frequently, however, the specified period

is part of a more extended period of low flow produced by general climatological and meteorological

trends. For this reason, it is difficult to ascribe probability estimates to low-flow ‘‘events.

Perhaps because of the difficulty of determining

low-flow probabilities, a common practice in planning and designing facilities for low-flow management has been to design for the ‘ ‘drought of record, i.e., the most severe low-flow period experienced in recorded history in a given watershed.

Because of natural variation and differences in the

length of available hydrologic records in different

watersheds, the ‘‘drought of record’ in some watersheds is very severe—perhaps with an estimated recurrence interval of 300 years or more—while in

other watersheds the drought of record may have

a recurrence interval of 20 years or less.

When the drought of record is used as a design

standard, some facilities are inevitably underdesigned and others are overdesigned. Thus, while

failures of flood control structures are rare, serious

inaccuracies in low-flow management facilities are

relatively common. Although alternative methods

have been developed for calculating streamflow sequences of long duration based on statistical analysis of relatively short historical hydrologic records,

planners have been reluctant to accept designs

based on statistical methods that differ substantially

from designs based on the “drought of record. ”

Considerably more work is needed on the use of

statistical methods for planning, designing, operating, and managing low-flow control facilities.

Public policy for dealing with low-flow problems

has focused more on water availability y policy than

on water use in low-flow periods—except with regard to competition among uses (irrigation, hydroelectric power, municipal water supply), which will

be discussed in the following subsection on streamflow regulation. Little use has been made of models

for regulatory aspects of low-flow management, except where interstate compacts or judicial decisions

have forced governmental entities to apportion low

flow among competing users. In general, available

models seem to be adequate for these needs.

Streamflow Regulation

The Nation has invested billions of dollars in

facilities to regulate streamflow for a variety of purposes: to reduce flood damage; to generate hydroelectric power; to provide stable navigation channels; to provide dependable surface water supplies

for municipal, industrial, and agricultural uses; to

improve fish and wildlife habitat; and to provide

recreational opportunities. Federal agencies alone

have constructed hundreds of structures that regulate streamflow for one or more of these purposes.

Thousands more have been constructed by other
Ch. 6—Modeling and Water Resource Issues ● 127 — —

governmental entities, private enterprises, and individuals. Most of these facilities are passive; i.e.,

they require little, if any, operational management

(other than routine maintenance) to accomplish

their intended purpose. Levees, ungated diversion

structures, and small dams with ungated spillways

are typical facilities that require minimal operational management.

Hundreds of these existing facilities, however,

are not passive. They are large, complex structures

serving many purposes and requiring intricate

daily, hourly, or sometimes even minute-to-minute

operational management to achieve their intended

purposes. Myriad conditions, criteria, and data

must be identified and evaluated each time an operational decision is made. Some operational

criteria are based on fixed conditions (e. g., those

that ensure the safety of the structure) while others

are based on changing phenomena (e. g., current

and future weather conditions). Operational management is further complicated in multipurpose

projects because some purposes are competitive (a

decision favoring one purpose has an adverse effect on some other purpose), while others are complementary (a decision favoring one purpose has

beneficial effects on other purposes). Operational

management problems are even more complex in

watersheds where two or more multipurpose projects exist. In this case, decisions for each project

must be coordinated so that the projects themselves

function in a complementary fashion.

Over the past decade, computer models that give

the project manager much greater flexibility than

previously used fixed operating rules have been

developed. Thus, it is now feasible to model the

operation of single projects or large systems of interconnected projects.

Many fixed operational rules have been replaced

by models that permit day-to-day decisionmaking

that can more effectively consider several objectives

of a project (or projects) simultaneously. Most of

the current models include only hydrologic inputs

and outputs, and the physical operation of a project or system. Economic, social, institutional, and

environmental factors affecting operational management are only considered indirectly, or evaluated outside the model. Despite their limitations,

these models have the capacity to improve both

short- and long-term operational management decisions and plans.

More recently, modeling capabilities for operational management of streamflow regulation structures have expanded to include mathematical optimization models and—in a few instances—online,

real-time models used for controlling major portions of a system’s operation. Some simulation

models have also been expanded to analyze economic, institutional, and environmental factors.

However, data acquisition (particularly for realtime operation) and model calibration are substantial obstacles to widespread use of the models currently available for large systems; many operating

entities do not have sufficient computer capabilities

and personnel to use the most sophisticated models

available for onsite operational decisions.

Instream Needs

Determining instream flow needs differs from

other water availability problems in that instream

flow needs are frequently linked to water quality

rather than water quantity requirements. The two

most common purposes for establishing instream

flow requirements are to preserve and protect

aquatic and riparian ecosystems, and to comply

with statutory, contractual, or institutional obligations to maintain the necessary streamflows.

The common practice of specifying instream

needs in terms of water volume dates back to the

earliest days of water resource development in this

country, when allocating water to meet these needs

was labeled ‘‘low-flow augmentation. While it was

recognized that many of the objectives of low-flow

augmentation were related to water quality characteristics rather than to water quantity per se, virtually all of the analytic techniques available for

planning and managing strearnflow regulation were

quantity oriented,

In the mid-1960’s, knowledge of water quantity/

water quality relationships and computer modeling capabilities simultaneously reached the point

where it became possible to model many important

water quality characteristics in reservoirs and

streams. The first such models dealt with the two

best understood quality characteristics—temperature and dissolved oxygen. These two characteris-
128 ● Use of Models for Water Resources Management, Planning, and Policy ——— —

tics were considered to be particularly important

because they are involved in virtually all physical,

chemical and biological processes occurring in

streams.

By the early 1970’s existing models were capable

of assisting planning efforts to meet instream needs

based on water quantity requirements, and providing information for some policy and regulatory aspects of instream-needs analysis. However, the

available models could not, in most cases, produce

results commensurate with requirements for operational management. New models that show promise for meeting the requirements for management

decisions have recently begun to appear.

The role of models in policy and regulation of

instream flow is limited by a lack of knowledge

about the qualities of instream flow required to ensure the survival of fish, wildlife, and other aquatic

and riparian biota. Many existing instream requirements are based on extremely limited information

concerning biological survival and tolerances. Most

existing standards establish a single value for instream needs, so that in essence a pass-fail condition exists. In policy and regulatory work, tradeoffs

are critical components of analysis, and tradeoff

analysis is severely hampered when degrees of success and failure cannot be analyzed. Improved understanding of relationships between instream flow

and biotic life would greatly enhance the utility of

existing models in policy and regulatory areas.

Water Use Issues

Domestic Water Supply

Domestic water suppliers in this country usually assume a utility responsibility —i.e., that of a

regulated monopoly—in their service area. In effect, they agree to provide services to all users within

the service area according to an established rate

structure, and to assure, insofar as possible, that

the service is equally available and dependable for

all users. This does not preclude the possibility of

establishing service classes or priorities for various

categories of users (e. g., differentiating between

purely domestic use and industrial use), but such

practices are much less common in the water supply

industry than in the electric power industry. Because of this ‘ ‘utility’ philosophy, water agencies

have traditionally worked much harder to secure

additional supplies than to control or manage

demands.

In many instances, domestic water use projections have consisted solely of projecting changes in

population and applying established per capita demand factors to the projected future population.

In some cases projections have been somewhat

more sophisticated. Some analysts recognize that

per capita consumption is affected by changes in

demography, technology, and lifestyles, and attempt to adjust current per capita consumption

estimates to reflect anticipated changes in these factors. However, only a modest amount of data is

available on which to base such adjustments.

As growth in domestic demands and competing

uses diminish the relative availability of water,

water utilities will have to develop and evaluate alternatives for obtaining additional supplies, or strategies for allocating available supplies among competing users. Models can be used to establish pricing policies, user priorities, and other economic and

technological aspects of system expansion. Models

can also play a useful role in examining the likely

responses of various sectors (domestic, commercial,

municipal, and industrial) to strategies that might

be used to achieve targetted reductions in use.

If priority use and pricing systems come into

widespread use, models will be needed to assist in

determining the conditions under which use priorities should be implemented, and the amounts of

water that should be made available to each user

class.

When additional supply capacity is deemed necessary, models can be used for planning efforts to

develop and expand water distribution systems.

These models focus primarily on the hydraulics and

economics of the distribution system itself rather

than on water use characteristics.

Irrigated Agriculture

Model use in the area of irrigated agriculture has

a relatively long history, and has grown more rapidly and is more widespread than for other water uses.

Since irrigation occurs primarily where rainfall is

deficient, farmers have had to be more conscious

of the importance of water and of the need to man-
Ch. 6—Modeling and Water Resource Issues 129

age a limited supply. Uses of models have ranged

from determining the need for irrigation water and

timing applications for specific crops, to developing policies for allocating water among users in

times of water shortage. Models are also used to

plan, design, and operate water distribution systems

for large irrigation projects.

Some of the models available for planning and

operational management of irrigation water are extremely sophisticated. They enable users to consider water requirements of individual crops over

an entire growing season or for specific intervals

within the growing season. The models can also

gage the effect of precipitation on the amount and

timing of needed irrigation water. Some of the most

sophisticated models permit users to consider options to defer applying water or to reduce the

amounts of water applied during periods of water

shortage. These models provide information on the

risks of crop failure or the likelihood of reduced crop

yields, thereby helping farmers to apportion limited

supplies among various crops. Such models also

provide information on the economic consequences

of buying and selling water entitlements.

The availability of these models to farmers involved in irrigated agriculture will be even more

important in the future, as competition between irrigation and other nonagricultural water uses increases in the Western States.

Other Offstream Uses

Water is also used for such purposes as cooling

in thermal electric power-generating plants; process water and cooling in coal gasification, shale oil

production and other energy extraction and conversion processes; hydraulic mining; and for use as a

transport medium in slurry pipelines. Many of

these uses require withdrawals of large quantities

of water from rivers and streams. In some cases

(e. g., evaporative cooling, slurry pipelines, and interbasin transfer) not only are the withdrawals

large, but the use is “consumptive’ ‘—i.e., the water

withdrawn is lost from the stream system from

which it was withdrawn. In other cases (e. g., oncethrough cooling, mineral extraction, and energy

conversion), while withdrawals are relatively large,

the use is not consumptive because the water eventually returns to the stream after use. In some of

these cases, however, the quality of the returned

water is substantially altered and the water may not

be fit for many other uses.

Models are currently available to assess the effects of offstream uses on water quantity and to

assess such common water quality characteristics

as temperature and dissolved oxygen changes.

However, improvements in models are needed for

assessing the economic and environmental implications of water withdrawals and potential water quality changes due to offstream uses.

Policy and regulatory functions are greatly affected by the lack of adequate modeling capability

in this problem area. The volume of some proposed

offstream uses—e. g., coal gasification or liquefaction and oil shale processing—is so large that decisions regarding them are likely to affect the economies and ecologies of large regions and involve

a considerable number of governmental jurisdictions. Information from models would be of great

value in resolving the controversies and interjurisdictional disputes that will inevitably arise.

Efficiency and Conservation

Models for dealing with water use efficiency and

conservation are considerably different from models

used in other aspects of water management. With

the exception of irrigated agriculture, water users

in this country have not emphasized efficiency and

conservation except during periods of critical water

shortages. Consequently, there is no substantial

body of knowledge regarding efficiency and conservation strategies and their economic, social, and

environmental consequences. Some data exist on

specific conservation practices and their effects in

isolated pilot programs under ‘ ‘normal’ conditions,

and some data exist on a wide range of conservation practices and effects under emergency conditions. However, it is doubtful that the existing data

base and knowledge (other than for irrigated agriculture) provides a sufficient basis for developing

the models needed for policy and planning functions.

Pertinent economic models—e, g., models to determine the effects of water pricing on use—are

discussed in “Social and Economic Models” of this

chapter.
130 . Use of Models for Water Resources Management, Planning, and Policy

Evaluation of Currently Available

Surface Water Flow and

Supply Models

model applications; for example, under the issue

of ‘flood forecasting and control, the capabilities

of models vary for the seven applications addressed.

Models are rated from A to F, with A indicating

that modeling for this purpose does a good job in

Table 7 presents evaluations of currently avail- supplying the needed information, and F indicating

able surface water flow and supply models. Each that the state of the modeling art for this purpose

water resource issue is subdivided into specific is generally unsatisfactory.

Table 7.—Surface Water Flow and Supply Model Evaluation

Overall

Issue Information required for applications rating

Water avaiiabiiity:

1. Flood forecasting and control

2. Drought and low-flow river

forecasting

3. Streamflow regulation

(including reservoirs)

4. Instream flow needs:

Fish and Wildlife

Recreation

Navigation

Hydroelectricity

Water use:

5. Domestic water supply

6. Irrigated agriculture

7. Other off stream uses

8. Water use efficiency

a. Flood peaks for channel and bridge design

b. Flood hydrography for reservoir design and operation

c. Simultaneous flood hydrography for flood control system design and operation

d. Flood depth mapping for flood plain land-use planning

e. Effects of land use on downstream flows for upstream land-use planning

f. Flood peaks after dam failures for emergency preparedness planning

g. Soil moisture conditions for land drainage design

a. Low river flows for off stream uses

b. Timing of drought sequences for estimating cumulative economic impact

c. Soil moisture conditions for precipitation-supplied uses

a. Runoff volume for maximum obtainable yield

b. Runoff time patterns (within and among years) for reservoir sizing

c. Simultaneous runoff volumes in regional streams for regional

water supply planning

a. Low river flows for estimating fish support potential

b. Within-year timing of low flows for fish Iifecycle matching

c. Timing of drought sequences for estimating minimum reservoir or lake levels

d. Flow velocities within streams for estimating effects on fish species

a. Low river flows for sustaining recreation capacity and esthetic appeal

b. Timing of flow sequences for matching with recreation periods

c. Runoff time patterns (within and among years) for estimating the impact of

fluctuations in lake levels

a. Low river flows for determining waterway capacity

b. High river flows for determining navigation interference

c. Formation of surface ice for determining navigation interference

a. Timing of flow sequences for estimating run-of-the-river

generating capacity

b. Runoff time patterns (within and among years) for designing

streamfiow regulations

c. Simultaneous runoff volumes in regional streams for regional generating

system planning

a. Timing of water use for delive~ system design

b. Water pressures throughout delivery system for delivery system design

c. Volume of use for sizing supply facilities

d. Return flow volumes for designing wastewater collection systems

a. Timing of water use for delivery system design

b. Volume of use for sizing supply facilities

c. Return flow volumes for drainage system design

a. Volume of industrial use for sizing supply facilities

a. Effect of increased use-efficiency on return flows for evaluating

conservation measures

B

c

c

c

c

D

c

c

B

c

A

B

c

c

B

B

c

c

B

B

c

c

D

B

B

c

D

c

B

c

c

B

B

B

c

Rating Key:

A Modeling of the physical process at the current state-of-the-art does a good job in supplying the needed information.

B Information between adequate and good.

C Modeling does an adequate job for most purposes.

D Information between unsatisfactory and adequate.

F The supplied information is generally unsatisfactory.

SOURCE: Office of Technology Assessment.
Ch. 6—Modeling and Water Resource Issues ● 131

SURFACE WATER QUALITY

Introduction

Billions of dollars are spent annually in the

United States to protect the quality of surface

waters. Unless carefully managed, residual wastes

from municipalities, industry, and agriculture can

seriously interfere with many beneficial water resource uses. Water quality models are used extensively in Federal, State, and local efforts to maintain and improve the quality of the Nation’s surface waters.

Water quality models serve two general functions. The first is to provide basic scientific insight

and understanding about the relationships between

material inputs and water quality changes. These

relationships are expressed in the form of mathematical equations that interrelate and synthesize observations. The second function is of an engineering nature. Once confidence in these relationships

is obtained, the equations can be used to help

manage, plan, and make policy. Given the present

state of scientific knowledge and engineering

development, existing models can generally provide a limited basis for water quality decisionmaking.

Mathematical models of water quality are most

frequently used for planning, to some extent for

policymaking, and to a lesser degree for day-to-day

operations and management. Their most common

use is to determine the degree of treatment required

for a specific wastewater discharge in order to

achieve or maintain a desired receiving water quali -

ty. Other uses include determining the magnitude

and effects of urban runoff, and assessing the effectiveness of alternative measures for preventing

soil erosion and the resulting sedimentation within

water bodies.

Because models simply quantify existing scientific knowledge about water quality, a basic understanding of the processes that underlie model equations and assumptions is helpful in assessing model

capabilities. The next section, ‘ ‘Types of Models

Used in Surface Water Quality Analysis, describes

the current state of scientific knowledge about determinants of water quality, and examines how well

this knowledge is incorporated into present water

quality models. Later, the state of the art of water

quality modeling is discussed on an issue-by-issue

basis, analyzing 10 major problems under the general categories of point and nonpoint pollution

sources. The section entitled ‘‘Evaluation of Currently Available Surface Water Quality Models’

assesses currently available model types. Evaluations are made both according to the characteristics

of the models themselves, and for the 10 major

problems to which they may be applied.

When considering water quality concerns, four

basic questions face the analyst:

1. What is the quantiy and quality of the water and

residuals coming from each point and nonpoint source?

2. How are these materials transported to the

receiving waters?

3. How are these wastes transported within the

receiving water?

4. What processes transform waste residuals within a water body?

Given the response of the system, the analyst

must further consider the following quest ions:

●

●

●

●

What deleterious effects do these wastes have

on beneficial uses?

Do existing standards reflect the magnitude

of the effects?

What control alternatives are available, how

well do they perform, and how much do they

cost?

Are these control alternatives politically, economically, and esthetically feasible?

All of the above information is needed for management, planning, and policy decisions. Models

are available, in varying degrees of detail and accuracy, to help the analyst address each of these

questions.

The common basis for the majority of water quality models is the principle of ‘‘mass balance.

Water and any material inputs from natural or human sources are followed: 1 ) from their point of

origin; 2) as they travel to the water body; and

3) as they travel within the water body. The models

account for biological, physical, and biochemical
132 . Use of Models for Water Resources Management, Planning, and Policy

reactions that occur, and additions of water or materials.

To run these models, users must provide quantitative estimates of the characteristics of the watershed and the receiving water body. Source quantities, constituents, and other pertinent characteristics

must be enumerated, and the numerical coefficients

that describe the above reactions must be known.

Water quality models have one aspect that is both

a vice and a virtue—most provide an absolute numerical value for any given variable such as the concentration of a pollutant. While it is desirable to

have such a number, often no indication of the

possible error is given. In practice, most water

quality projections are subject to large errors and

must be validated with field observations.

However, water quality models are still very useful in planning contexts, for example, because relative effects of control alternatives can be analyzed

with sufficient confidence for many purposes. Model projections, when combined with the professional

judgment of water resource analysts, are often the

best information available to aid the decisionmaker

in evaluating alternatives.

Types of Models Used in Surface

Water Quality Analysis

All water bodies are affected by inputs from natural sources and human activities. The accuracy

with which models can estimate relationships between these inputs and the water quality response

determines their utility for management, planning,

and policy purposes. Thus, current levels of scientific and engineering knowledge about these relationships form the basis for assessing surface water

quality models.

Water quality models can be divided into three

components that describe:

● source of materials;

● transport to and within the receiving water;

and

● processes occurring within the receiving water;

The first component estimates the inputs of substances through human activities and natural phenomena; the second, the hydrologic and hydrodynamic regime of the water body and its watershed; and the last, the biological, chemical, and

physical processes that affect water quality.

Source of Materials

Water bodies may receive point source discharges

from municipal, industrial, and agricultural activities; dispersed or nonpoint source runoff from these

same areas; natural inputs from undisturbed watersheds; and additional chemicals from rainfall.

The chemical characteristics of effluents from

municipal sources are well known with respect to

both average values and their variations. This is

also true for many industries that generally produce one or a few products, such as the pulp and

paper, canning, and steel industries. However, industries that produce a variety of products, such

as organics, synthetic chemicals, and pharmaceuticals, produce discharges that are more difficult to

characterize.

Information on agricultural and feedlot sources

of waste is meager, but has been improving in recent years. Irrigation return waters pose difficult

problems, particularly in the mid- and far-western

regions of the country where high background concentrations of salts of natural origin prevail. The

time-variable nature of return flows, which are both

point and distributed, introduces additional complexities. Our social and scientific awareness of

these problems is relatively recent; consequently,

the historical data on these sources are minimal,

and many gaps remain in current knowledge of the

governing phenomena.

The ability to quantify pollutant loadings from

a variety of sources is critical, particularly with

respect to differentiating between point sources,

which are readily controllable, and nonpoint

sources, which are relatively difficult to identify and

control. Assigning realistic values to distributed

nonpoint sources is very difficult, given the present state of knowledge and data, Current models

provide at least some assessment of the problem.

The most significant information gap lies in

quantifying toxic substances from nonpoint sources

or from residues of toxic materials created by past

activities, e.g., from riverbeds and from landfills

that leach into water systems.
Ch. 6—Modeling and Water Resource Issues ● 133

Transport to and Within Receiving Waters

Point discharges are transported by pipes, open

channels, or other conveyance devices from the

point of origin to the receiving water on a regular

basis. Nonpoint discharges move through storm

drainage systems, via overland flow, and through

subsurface flow to the receiving water as a result

of rain events. Consequently, the quantities of

materials entering water bodies from nonpoint

sources are much more difficult to predict.

Most surface water quality models include a surface water flow submodel as part of the program,

since in most cases it is necessary to predict runoff

and flow quantities before making quality estimates.

Many of the models discussed in the previous section on surface water flow are used as components

of surface water quality models.

Pollutant transport by rivers and streams is, in

general, better understood than transport within

lakes. Transport in streams depends primarily on

flowing water; within lakes, and some complex river

systems, movement of pollutants occurs by diffusion and dispersion as well—difficult processes to

model. In addition, a longer and more extensive

data base is available for streams than for lakes.

Transport in streams can be approximated by

simple one-dimensional models—the one dimension being the direction of flow. Under certain conditions, simple models can adequately simulate

transport in lakes, but often more complex two- and

three-dimensional models are necessary. The state

of knowledge and computational techniques are

such that only the most proficient analysts can use

these models.

The above remarks apply to situations that are

not highly time dependent. When water quality

analysis must incorporate such factors as storm

surges from combined sewers or rapidly changing

river flows, the models must be considerably more

complex. These models are still in the developmental stage and their results are only marginally useful

at present.

Processes Occurring Within

the Receiving Water

In general, the chemical, physical, and biological

processes of rivers and streams are better modeled

than those of lakes. In addition, more extensive water quality data exist for rivers and streams, particularly for such constituents as dissolved oxygen

and coliforms (bacteria used to indicate the presence of sewage).

Eutrophication (excess algae or aquatic weed

growth) is another widespread problem. The nutrients that cause eutrophication originate from a variety of municipal, industrial, agricultural, and natural sources. While the state of the art permits some

model-based assessment, data requirements are so

extensive that these techniques are often impractical. Simplified approaches, involving the nutrients

phosphorus and nitrogen, presently yield results

that may be indicative and, in certain cases, adequate for the intended purpose.

For inorganic and organic chemical water quality, the present state of knowledge is mixed. The

biochemical reactions of certain industrial chemicals

are sufficiently understood to permit the development of reliable models. This is true for a wide

range of chemical compounds of relatively simple

structure, which are commonly present in industrial

effluents and which are susceptible to the presently available treatment processes. While the reactions involving metals are not as well understood

as those of the simple industrial chemicals, they

have been developed to a degree that will permit

at least a marginal analysis and projection.

On the other hand, for more complex compounds, many of synthetic composition, far less is

known about reactions, byproducts, and removal

by present treatment techniques. These substances,

which inciude many toxic materials, may be modeled with simplifying assumptions, yielding reasonable projections in limited cases. However, on the

whole, current methods of analysis are regarded as

only marginally reliable, A similar assessment ap-

plies to complex metals when concentrations approach or exceed toxic limits. Water quality models

that analyze these substances are presently being

developed.

A second area of notable uncertainty is the accumulation of toxicants in the food chain leading to

fish. Much research has been undertaken over the

past decade to advance basic understanding of the

problem, collect data, and develop models, some

of which appear to be very promising. Preliminary
134 ● Use of Models for Water Resources Management, Planning, and Policy

—— .—

Photo credits: @ Ted Spiegei, 1982

Researchers are exploring natural capabilities to reduce nutrient levels in effluent flows as a potential means of tertiary

sewage treatment. At left, water in a meandering stream is cleansed through contact with vegetation and reaerated

on its way to the Hudson River; at right, a Florida cypress dome is fertilized with the nutrients in partially treated

effluents from a 150-unit mobile home park. Models are available to estimate the effectiveness of various treatment

methods in removing such nutrients as phosphorus and nitrogen, and to assess the effects of nutrients on biological

processes in lakes and streams

food chain and fisheries models are available; however, these are in a relatively primitive state. Although they may provide some insight and understanding, they are neither sufficiently calibrated nor

adequately validated for management purposes.

The same may be said for aquatic ecosystem

models that describe changes to aquatic plant and

animal populations subjected to water quality

stresses. Ecosystem theory-the basis for such models—is still in a developmental stage. However, the

results of laboratory studies on the effects of specific

pollutants on sensitive organisms have been incorporated into water quality models with some success.

Nonpoint Source Issues

Urban Runoff

Urban runoff (along with agricultural runoff) is

one of the most difficult waste discharges to control because of its intermittent nature and varying

quality. Federally mandated control and management of urban runoff has created the potential for

increased use of urban runoff models.

At present, urban runoff models are most helpful

in planning, primarily for water quality management and comprehensive areawide planning. The

best examples lie in the section 208 programs of

the Clean Water Act—particularly the Nationwide
—

Ch. 6—Mode/ing and Water Resource Issues 135

Urban Runoff Program. Such planning is designed

to provide each State and the Environmental Protection Agency (EPA) with information on point

source and nonpoint (including urban runoff) treatment needs and the effectiveness of treatment methods. Urban runoff models such as EPA’s Stormwater Management Model and the Corps of Engineers’ STORM can simulate the quantity and

quality of runoff from a specified runoff area and

can be used to compare the effectiveness of alternative control strategies. These models may also

be linked to receiving water models to gage the effects of urban runoff on receiving water quality.

Urban runoff models can also play an important

role in Federal and State agency policy decisions.

Federal agency construction grants allocations, and

requests for such funds by State agencies, could be

based in part on estimates of the volume and quality

of point source and nonpoint source wastes in a

specific area, the effects of these wastes on the

receiving water, and the effectiveness of nonpoint

source control in alleviating the problem.

Urban runoff models do not appear to have attained the credibility necessary to be used as regulatory tools at this time. These models require an

extensive local data base, and such information is

usually unavailable, except for cities in which specific studies have been performed to develop, calibrate, and test such models.

Erosion and Sedimentation

Models of erosion and sedimentation are developed primarily by such Federal agencies as the

Corps of Engineers, the Soil Conservation Service,

the U.S. Geological Survey, and, to a lesser extent,

Photo credit: U.S. Department of Agriculture

Two years of low rainfall on the Big Canyon Ranch near Sanderson, Tex., greatly reduced plant cover levels, setting

the stage for extremely high runoff rates on the draw pictured above after rainstorms hit an area 30 miles away. Plant

cover is a major determinant of soils’ abilities to absorb moisture and resist erosion; runoff and erosion models consider

cover levels as one of many factors in estimating flows and sediment transport
136 ● Use of Models for Water Resources Management, P/arming, and Policy

EPA. Extensive use is made of erosion and sedimentation models by Federal, State, and local agencies concerned with river management. Construction agencies use these models to assist in operational management, e.g., in dredging navigation

channels and operating reservoirs. Sedimentation

is a critical factor in reservoir management, as it

can reduce a reservoir’s useful volume. River

authorities must have information on rates of

sedimentation and ways of alleviating or minimizing sedimentation to operate their reservoirs

most efficiently.

Local, State, and Federal agencies concerned

with forestlands, rangelands, and farmland management continually seek better ways to minimize

soil erosion. They employ models to guide the selection of effective management techniques.

A primary concern is the large amounts of nutrients (especially nitrogen and phosphorus) contained in eroded soils. Soils reaching waterways

may impart those nutrients to the water, potentially

causing nuisance algal growths or other symptoms

of eutrophication.

Probably the greatest utility of erosion and sedimentation models lies in the area of planning. For

example, the Corps of Engineers employs such

models to plan and design erosion control structures along rivers and coastal areas and to estimate

the extent of sediment accumulation over the life

of a reservoir. The Soil Conservation Service uses

erosion models to plan erosion control programs

on farmlands and forestlands.

Because toxic chemicals often adhere to river

sediments, sediment transport models are used to

predict the movement and fate of toxicants accidentally released into waterways. EPA relies on water

quality models incorporating sediment transport

submodels to follow the transport of Kepone down

the James River to the Chesapeake Bay. The agency is using this information to plan monitoring programs and subsequent mitigation programs, if

needed.

Salinity

Several factors may cause the buildup of excess

salinity in surface waters. One major source is irrigation return flows. To maintain a favorable salt

balance in agricultural soils, farmers may apply

more water to their crops than is required for plant

production. The additional water leaches out excess soil salts that may either flow overland to surface waters or percolate to the ground water. The

erosion of soils with high salt contents, such as the

marine shales found extensively in the West, and

the input of salts from natural sources, such as

brines, also contribute to excess salinity. Finally,

the concentration of salt in surface waters can increase due to evaporation, reductions or diversions

in flow, and plant transpiration.

Salinity, as a physical process, is one of the best

understood pollution problems, and relatively easy

to model, Many models exist to predict salt concentrations in agricultural drainage as a function of

crop, soil type, and irrigation practice; downstream

salinity concentrations; and the effects of excess

salinity on crops, metal deterioration, soap consumption, and health. A well-developed data base

complements these models.

Models are widely used to develop management

strategies for salinity control. They can provide

managers with information on the effectiveness of

control options for reducing downstream salt concentrations. In addition, these models are useful

for evaluating the likely effects of proposed regulations. From a planning standpoint, these same

models are used to develop areawide salinity control plans and can aid in setting funding priorities

to implement these plans.

In the ares of policy, salinity is an important

aspect of international water rights issues and treaty

obligations between the United States and Mexico. In particular, the salinity of the Colorado River

has been a major international issue for some years.

The increase in salinity of the Colorado from saline

return flows before it leaves the United States is

a major problem for water users in Mexico. Models

have been used to determine whether planned consumptive uses from the Colorado Basin will allow

the United States to meet its treaty obligations for

delivering water at or below a specified salinity.

Agricultural Pollutants

Agricultural pollutants are found in runoff from

irrigated and nonirrigated agricultural lands and

pastures. The pollutants include soil particles
Ch. 6—Modeling and Water Resource Issues ● 137

eroded from the land; organic substances from

decaying vegetation, animals, and feedlot waste;

nitrogen and phosphorus from commercially produced fertilizers as well as from animal waste; and

pesticides that have been applied but are not yet

degraded. These pollutants find their way into nearby receiving streams, where their effects must be

assessed.

Agricultural pollutants are generally considered

to originate from nonpoint sources; animal feed

lots, however, are considered point sources. Like

other point sources, the latter must be treated to

meet effluent and receiving water standards according to sections 301 and 303 of the Clean Water Act.

Nonpoint sources are eventually to be controlled

as well, but standards and guidelines for implementing controls have not yet been promulgated.

Mathematical models aid in assessing the instream effects of these point and nonpoint sources

—such analyses play an important role in regulating

pollution sources. The models for tracking organic

materials and their effects on oxygen resources in

streams are well developed, well documented, and

easily usable by personnel with appropriate analytical skills and knowledge of water quality management principles. Such models should also withstand

the scrutiny of litigation. Models for nutrients and

pesticides, however, are not used as broadly as

models that predict levels of dissolved oxygen.

Mathematical modeling of agricultural pollutants

finds extensive use in planning. Models have been

used primarily for section 208 studies of areawide

pollutant problems and water treatment needs.

Such studies enable States and EPA to establish

priorities for treatment, based on estimates of the

effects of point and nonpoint sources on receiving

waters.

Not only do Federal and State agencies use mathematical models for the kind of planning mentioned

above, but they also use these models to determine

the effectiveness of treating agricultural pollutants,

recommend funding levels to Congress, and propose legislation for controlling agricultural

pollutants. In these cases, mathematical models

may be the only means of linking the pollution

source to effects on the receiving waters—a connection that is important in estimating the benefits

of regulatory programs.

i

Photo credit: @ Ted Spiegel, 1932

Agriculture can also serve as a means of treating certain

water pollutants. Lubbock, Tex., utilizes a 3,000-acre farm

as its tertiary disposal facility, employing nutrient-laden

waters to irrigate and fertilize crops

Airborne Pollutants

Since the enactment of the 1971 Clean Air Act,

mathematical models have been used as regulatory

tools by Federal and State agencies that are assigned

responsibility for air pollution enforcement. Such

models determine the relationship between discharge and downwind exposure concentrations of

common air pollutants such as sulfur oxides, nitrogen oxides, and particulate. Some of these pollutants are transferred from the air medium to water

and thus contribute to water pollution. Such materiah include windblown dust, hazardous substances,

and compounds that may eventually produce acid

precipitation.

The transfer of pollutants from air to water has

received increasing attention in the last few years.
138 . Use of Models for Water Resources Management, Planning, and Policy

Hazardous substances in incinerator effluents and

windblown erosion from landfill sites are problems

for which mathematical models may be used to anticipate and formulate control strategies. Models

of short-range pollution transport (less than 200

km) are currently available. The potential consequences of acid precipitation, and of the deposition of heavy metals, radioactivity and other hazardous materials from powerplant air emissions,

may require Federal and State agencies to assess

future water quality problems resulting from increased energy production. Models of long-distance

pollution transport, and of atmospheric processes

that may produce acid rain, are in early stages of

development.

Point Source and General Issues

Wasteload Allocation (Point Source)

Wasteload allocation refers to the process of

determining the amount of some waste material that

a particular discharger is allowed to release by analyzing the relationship between discharged amounts

and resulting concentrations in the receiving water.

This cause-effect relationship may be determined

after the fact through sampling programs, or before

discharges occur with the help of mathematical

models.

Water quality models find their most appropriate

regulatory roles in estimating waste treatment needs

for compliance with the Clean Water Act. The act

sets forth two criteria for water quality standards:

1) effluent requirements for regulating ‘ ‘end-ofpipe” discharges, as specified in section 301 of the

act; and 2) receiving water standards, as specified

in section 303 of the act. Discharges who meet effluent standards may be required to provide further treatment if resulting waste discharges cause

higher-than-acceptable receiving water concentrations. Wasteload allocation models determine the

maximum allowable level of discharge for individual producers in order for pollutant concentration

levels in receiving waters to be at or below existing

standards. Removal techniques to meet these limits

can then be selected.

Mathematical models for this procedure are well

developed and documented, can be adapted to receiving waters of different types, can be easily used

by regulatory staff, and are reliable enough to withstand judicial scrutiny. Waste allocation is particularly complex, however, when a number of

discharges reach a common receiving water near

the same point. In such cases, the allowable

wasteload can again be determined by a mathematical model, but assigning wasteloads equitably

among the contributors must be a legal and administrative decision.

Water quality models have been used extensively

in planning for treatment needs throughout the Nation. As part of section 208 of the Clean Water Act,

point and nonpoint wasteloads were to be determined for segments of the Nation’s waterways.

Mathematical models were used in these cases, first

to estimate current loadings from the point and

nonpoint sources, and then to estimate the impact

of these loadings on the receiving stream. Based

on the magnitude of these effects, the need for

wasteload reduction was determined. Then, based

on the ratio of point source to nonpoint source discharges, Federal and State agencies could estimate

where the greatest water quality improvement could

be achieved at the least cost.

Probably the most dramatic and exemplary policy-level application of these water resource models

was undertaken by the National Commission on

Water Quality. The commission, mandated by

Congress as part of the 1972 Federal Water Pollution Control Act Amendments (Public Law 92-

500), undertook a number of assessments of the

social, economic, technical, and environmental impacts of implementing the other sections of the act.

Among the commission’s responsibilities were a set

of water quality studies to evaluate the act’s impact on some 40 specific areas around the United

States. Water quality models were used extensively in these studies and were, in fact, necessary to

carry them out. Study results indicated that the effluent regulations of the 1972 act should be altered

to reflect more realistically attainable levels of treatment in the allotted time periods. The work of the

commission contributed to policy changes within

EPA, and influenced congressional formulation and

passage of the 1977 Clean Water Act (Public Law

95-21 7), which incorporated many of the commission’s recommendations.

Wasteload allocation models were critical to the

commission’s ability to demonstrate the consequences for the Nation’s receiving water quality of
Ch. 6—Modeling and Water Resource Issues ● 139

Photo credit: EPA-DOCUMERICA, Doug Wilson

Untreated water from a pulpmill in Puget Sound, Wash.

implementing the 1972 act. The study also revealed

some shortcomings in then-current modeling capabilities, however. Contractors performing work for

the commission relied primarily on dissolved solids

and dissolved oxygen models; models for nutrients

and toxic materials were applied in only a few situations, largely because existing data bases were inadequate for calibrating and validating them.

Thermal Pollution

Thermal effluents are among those regulated by

the Clean Water Act. Effluent limits have been set

for thermal wastes as well as for allowable temperature increases in receiving waters. Zones of influence and resulting temperature increases from thermal effluents can either be monitored directly or

predicted with mathematical models.

Mathematical models for thermal wastes range

from fairly simple one-dimensional models to more

complex two- and three-dimensional models. Most

of these models have been developed through the

support of EPA and the electric utility industry and

have been applied in many locations. Most regulatory staffs can operate the simpler thermal waste

models, but the more complex multidimensional

models require well-trained staff.

The electric utility industry uses mathematical

models extensively in applying for construction and

operation permits for nuclear powerplants through

the Nuclear Regulatory Commission, and in preparing environmental impact statements as required by the National Environmental Poiicy Act

of 1969. Under the latter act, the permittee must

show the extent of the environmental impact of its
140 ● Use of Models for Water Resources Management, Planning, and Policy

facility, in particular the impact of the thermal

waste. Such effects are routinely forecasted by using

mathematical models.

Toxic Materials

Compounds that cause some injury to humans

or other organisms of concern are classified as toxic

materials. Such materials are not necessarily lethal,

but may be compounds that produce such sublethal

effects as cancer, birth defects, or reproductive

failure.

Toxic materials are regulated under several statutes, including the Clean Water Act, the Toxic

Substances Control Act of 1976 (Public Law

94-469), the Resource Conservation and Recovery

Act of 1976 (Public Law 94-580), and the Safe

Drinking Water Act of 1974 (Public Law 93-523).

Regulation under this last act is discussed in the

section entitled “Ground Water Quantity and

Quality. ” Although control is focused on technology-based standards, mathematical models have

potential roles in enforcing portions of these acts.

As with other pollutants, effluent requirements have

been established for point sources based primarily

on removal techniques. However, receiving water

criteria must be met as well. Modeling for toxic

material concentrations may be required at some

future time to determine further treatment needs

if receiving water standards are not being met.

While legislation exists for control of nonpoint

source toxicants, implementation has been given

low priority. As controls are applied, however,

ground and surface water quality models could play

an important role in determining the cost effectiveness of alternative control measures, Mathematical models can also be used to design monitoring

networks so that stations can be best located and

sampled to gain maximum information from monitormg.

As with other issues, mathematical models for

toxic materials have greatest utility in the planning

process. Models can be used to anticipate problems,

and to test different management approaches for

removal effectiveness and managerial efficiency.

Since regulations for controlling liquid and gaseous

sources of toxic substances are currently being implemented, and those for hazardous solid wastes

have recently been issued, models for planning

long-term toxic material control should find widespread application.

Drinking Water Supply

The Safe Drinking Water Act is the principal

Federal legislation regulating the quality of drinking water. It, along with State statutes and local

ordinances, regulates the quality of public drinking water. Regulations apply to water quality at

the end of the treatment process; consequently,

streamwater quality models have no roles per se

in regulating drinking water under this act. However, toxicology models, which relate concentrations

of various hazardous substances to human health

risks, are used to aid in setting standards. These

models use differing methods for extrapolating data

from animals to humans, so that resulting estimates

of human risk may diverge widely. The OTA report, Technologies for Determining Cancer Risks From

the Environment, provides an assessment of toxicology

models.

The quality of the raw water is an important factor in supplying high-quality water for human consumption. Where raw waters are degraded by upstream users, water quality models can be used to

predict water quality at the point of intake to determine the level of treatment needed. In particular,

water quality models are used in determining when

intakes should be closed due to contaminants originating upstream. For example, a spill of carbon tetrachloride in the Ohio River several years ago

forced water users downstream to close intake structures at appropriate times to avoid contaminating

the water supply. Models were used to predict when

and how long the carbon tetrachloride would be in

the vicinity of the intake structures.

Water Quality Impacts on Aquatic Life

Models for predicting water quality impacts on

aquatic life involve two steps: 1 ) estimating concentrations of those materials that may affect aquatic

life (positively or negatively), and 2) comparing

calculated concentrations with accepted criteria to

judge the consequences of those concentrations to

the ecosystem. This latter step is seldom incorporated into the model structure, and requires professional judgment by aquatic ecologists.
Ch. 6—Modeling and Water Resource Issues ● 141

The models used to assess impacts can vary from

very simple models for calculating the effects of concentrations of selected materials, to very complex

models incorporating several different types of

pollutants and their effects on numerous organisms.

The complex models are the least reliable, due to

the lack of data to support many of the necessary

assumptions and the great difficulty in calibrating

and validating them. Both types of models require

considerable professional judgment in applying the

results to field situations.

Models to determine water quality impacts on

aquatic life are primarily of value in the planning

process. This is due to the kinds of applications that

can be made of these models, the current state of

their development, and the number of areas for

which data are adequate to apply them.

Aquatic life impact models can be usefully applied if a theoretical analysis of the aquatic system

is coupled with coefficients derived from controlled

laboratory experiments. Examples include models

of the movement and effects of Kepone in the James

River, of polychlorinated biphenyl (PCBS) in the

Hudson River, and of PCBS in the Great Lakes.

Both the Kepone and PCB models facilitate impact

assessment by allowing researchers to compare exposure concentrations to tolerable levels, while the

P(2B models can predict alterations in populations

if toxic interactions are included. These models

have been used to forecast the effectiveness of alternative remedial actions, and thus help provide a

basis for future regulatory activities.

Evaluation of Currently Available

Surface Water Quality Models

A model’s level of complexity and its degree of

availability provide the basis for a simple scheme

of classification. Accordingly, four generic types of

models are outlined below, and their basic capabilities are summarized. In the evaluation table (table

8), these four generic model types are rated according to their utility in analyzing five major aspects

of each of the 10 issue areas discussed above. The

evaluation table also assigns an overall rating for

modeling sophistication in each issue area. Using

a potential scale of zero to 10, actual assigned

ratings range between 1 and 9, indicating the

uneven level of current modeling capability for surface water quality analysis.

Type Z is a standardized procedure or technique

that may be routinely performed without a computer. It involves simple mathematical equations,

statistical techniques, and graphical procedures. Examples include use of the Streeter-Phelps stream

model for evaluating dissolved oxygen downstream of point sources (although this is often programed into complex models), and evaluating lake

eutrophication potential with diagrams or regression equations. While the procedure does not involve a computer, it is not necessarily unsophisticated. On the contrary, some ‘‘desktop’ procedures are mathematically quite sophisticated,

whereas some complex digital computer models are

nothing more than a programed version of intuition. Finally, a Type I model may still require considerable time and effort and the use of computational aids (e. g., hand calculators) to be fully operational.

Type II is a computerized version of a Type I

model. This may avoid the tedium of routine calculations and greatly expand the amount of data that

can be processed. The level of complexity of the

analytical technique, however, is still low.

Type III is a procedure that is sufficiently complex that a computer is required for its use. Such

models generate numerical solutions for sets of

mathematical equations that could not be solved

prior to the advent of modern computers. Many

individuals, consultants, universities, industries,

and public agencies have constructed such models.

Type IV is the same as a Type III model except

that it is termed operational, meaning: 1) documentation (e. g., user’s manual, description, and theory)

is available; 2) the program has been well tested

and its credibility established by groups other than

the model developer; 3) the program is available

and accessible to interested users (this does not preclude proprietary models); and 4) user support is

available either from the model developer or from

other groups. Although several hundred large water

quality models are described in the literature, less

than 100 can be termed operational. A Type IV

model can thus be used by others with relative ease.
142 ● Use of Models for Water Resources Management, Planning, and Policy

Table 8.—Surface Water Quality Modei Evacuation

Generic type

Iv

I II Ill Computer, Overall level

No computer, Computer, Computer, complex,

Issue

of modeling

not complex not complex comDlex operational sophistication

Nonpolnt source pollution and land use

Urban runoff:

Source/generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Transport to receiving water. . . . . . . . . . . . . . . . . . . . .

Transport in receiving water. . . . . . . . . . . . . . . . . . . . .

Impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .

Control options/costs. . . . . . . . . . . . . . . . . . . . . . . . . . .

Erosion and sedimentation:

Sourcelgeneratlon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Transport to receiving water. . . . . . . . . . . . . . . . . . . . .

Transport in receiving water. . . . . . . . . . . . . . . . . . . . .

Impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .

Control options/costs. . . . . . . . . . . . . . . . . . . . . . . . . . .

Salinity:

Source/generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Transport to receiving water. . . . . . . . . . . . . . . . . . . . .

Transport in receiving water. . . . . . . . . . . . . . . . . . . . .

Impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .

Control options/costs. . . . . . . . . . . . . . . . . . . . . . . . . . .

Other agricultural runoff:

Source/generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Transport to receiving water. . . . . . . . . . . . . . . . . . . . .

Transport in receiving water. . . . . . . . . . . . . . . . . . . . .

Impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .

Control options/costs. . . . . . . . . . . . . . . . . . . . . . . . . . .

Airborne pollutants:

Source/generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Transport to receiving water. . . . . . . . . . . . . . . . . . . . .

Transport in receiving water. . . . . . . . . . . . . . . . . . . . .

Impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .

Controi options/costs. . . . . . . . . . . . . . . . . . . . . . . . . . .

Water quality (other than nonpoint sources and land use)

Wasteioad allocation:

Source/generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Transport to receiving water. . . . . . . . . . . . . . . . . . . . .

Transport in receiving water. . . . . . . . . . . . . . . . . . . . .

Impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .

Controi options/costs. . . . . . . . . . . . . . . . . . . . . . . . . . .

Thermai poiiution:

Source/generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Transport to receiving water. . . . . . . . . . . . . . . . . . . . .

Transport in receiving water. . . . . . . . . . . . . . . . . . . . .

impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .

Controi options/costs. . . . . . . . . . . . . . . . . . . . . . . . . . .

Toxic materiais:

Source/generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Transport to receiving water. . . . . . . . . . . . . . . . . . . . .

Transport in receiving water. . . . . . . . . . . . . . . . . . . . .

Impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .

Controi options/costs. . . . . . . . . . . . . . . . . . . . . . . . . . .

Drinking water quaiity:

Source. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Treatment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Impacts on beneficial use. . . . . . . . . . . . . . . . . . . . . . .

Water quality impacts on aquatic iife. . . . . . . . . . . . . . .

Key: A Reliable, credibie modeling may bereadily used for most problems ofthis subissue. Some models maybe suitable forreguiation and design,

B Same as C, but some models may beuseful for planning andrelated purposes, and suitabie for determining relative effects.

C Modeling lspossible. Credibility andreliability of results is Iowdueto weaknesses in the database.

— Modeling of this type is not usually performed.

Overall level of modellng sophistication:

O No models available.

10 Routine use of models of all types,

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Ch. 6—Modeling and Water Resource Issues ● 143

It is not possible to state categorically that one

type of model is to be preferred over another—in

particular that a Type IV model is to be preferred

over a Type 1. The appropriateness of an analytical

tool depends on the particular problem and objectives of the analysis. In the most general terms,

Type III and IV models have greater potential for

accuracy and credibility than do Type I and II models. But there are many instances in which data and

theoretical formulations are so lacking that the use

of a complex computerized model is simply not warranted, even if one already exists. For example, the

fate of toxics in the environment is of immediate

concern to the public, but the various parameters

and coefficients that describe the sources, sinks, and

transformations of these chemicals are so ill-defined

that the sophistication of toxic model formulations

far outstrips the present data base. Simpler procedures are often much more credible.

The evaluation table presents a summary of informed opinion regarding the utility of models in

analyzing specific issue areas. Overall, models are

currently judged most successful for the issues of

salinity, wasteload allocation and thermal pollution.

The weakest issue is toxics, due mainly to the lack

of data necessary to determine the changes these

substances undergo in receiving waters.

Successful modeling for a given issue requires

a good deal more than the application of sufficient

modeling expertise. To model the governing principles of physical processes, the principles themselves must be well understood. Scientific understanding of biochemical phenomena related to water

quality is not sufficiently advanced to permit highly

accurate modeling; the governing principles of temperature, on the other hand, are relatively well documented. Data constraints place a further limitation on the utility of models—processes that are

thoroughly understood can be accurately modeled

only if data are available to predict conditions for

the location under study. This evaluation accounts

for these factors in assessing model utility, rather

than simply assessing the state of the modeling art

in itself.

GROUND WATER QUANTITY AND QUALITY

Introduction

Ground water systems, unlike surface water systems, are completely concealed from view; consequently, conceptual, physical, or mathematical

models are the only way to achieve an understanding of their potential yields and responses to natural

or man-related stresses. Simple ground water problems may be analyzed using physical hydraulic concepts and assumptions, perhaps expressed in simple paper calculations. However, more complex applications require the use of large amounts of data,

gathered from multiple test wells at many different

times. The only way to integrate this information

involves using computers that are capable of solving hundreds or even thousands of complex mathematical expressions simultaneously.

Public agencies that issue water use permits or

otherwise manage regional ground water resources

must rely on models to forecast effects of ground

water use. Applications range from day-to-day

management of a community’s ground water use

to long-range Planning for maximizing the utility u .

of an entire aquifer. Models can be designed, for

example, to calculate how pumping from a new well

might affect local ground water levels, or to predict

how far contaminants might move in a given period

of time. However, models can also be designed to

answer more complex questions about potential

quantities of recoverable water in regional ground

water systems as more and more wells are drilled

and pumped. These evaluations can provide information for regulatory decisions regarding allowable

limits on total ground water use, optima] pumping rates and placement of new wells, or controlling subsurface waste injection that may contaminate ground water.

The principal types of situations for which models are used include:

. changes in ground water availability;

● changes in ground water levels due to pumping from wells, land drainage, or injecting

water into an aquifer;
144 ● Use of Models for Water Resources Management, Planning, and Policy

●

●

●

changes in ground water flow caused by alterations in surface water flow patterns;

movement of contaminants through ground

water systems from waste disposal or encroachment of saltwater; and

settlement or subsidence of the land surface

due to withdrawals of ground water.

The greatest limitations on the effective use of

ground water models are not computer size or accuracy, but: 1) the basic understanding of physical

and chemical processes in ground water systems;

2) the cost of collecting sufficient field data to

describe the characteristics of the ground water system; and 3) the availability of well-trained personnel. In general, ground water quality models are

much less reliable than ground water flow models.

While models are widely used to address ground

water availability questions, many ground water

quality models have not yet been proven reliable

enough for routine regulatory application.

Types of Models Used in Ground

Water Resource Analysis

Ground water models are usually classified according to the physical and chemical processes they

describe. The two major types are: 1) ground water

flow models; and 2) contaminant transport models.

Generally, ground water quantity and yield problems are analyzed with flow models, while ground

water quality issues require the use of contaminant

transport models. The two major model types are

examined below, and ground water quantity and

quality issues are analyzed in “Ground Water

Quality Issues. ” Lastly, the section evaluates the

utility of currently available ground water models.

Ground Water Flow Models

Flow models determine rates and patterns of fluid

movement through soil or rock. Both the type of

fluid and the nature of the soil or rock are used to

further characterize the flow model. Types of fluids

modeled include water only, water and air, or water

and an immiscible fluid (a fluid that does not mix

with water, such as gasoline). The soil or rock types

may be either porous or fractured material. Flow

in porous media is primarily through interconnected

voids (open spaces) between individual grains. An

example of this type of material is sandstone. In

fractured media, water cannot move through the rock

as in porous flow, but moves through cracks or cavities in the rock. In general, better estimates of flow

can be made with models for porous media than

for fractured media.

Saturated flow models consider the flow of water

only. These models assume that water completely

fills the open spaces between soil grains or rock.

Data used in these models include: 1) inherent

characteristics of the system, such as the transmissivity (ability to transmit fluids) and storage (ability

to store fluids) characteristics of the rock or soil;

and 2) changes imposed on the ground water system, such as water entering or leaving the system.

Results from the model consist of calculated fluid

pressures or water levels at time intervals for specific

locations in the ground water system. Saturated

flow models are used for almost all types of ground

water quantity applications.

Above the water table, the open spaces between

soil grains or in rock voids contain air as well as

water. A model that considers a mixture of air and

water simultaneously is called an unsaturated~ow

model. Data requirements for unsaturated flow models include all of those needed for saturated flow

models plus data describing the reduction in transmissivity (resistance to water flow) due to the presence of air. Besides fluid pressures, the models also

calculates variations in the amount of air contained

in the pore spaces. Unsaturated flow models are

useful for small-scale problems such as crop irrigation or water flow adjacent to landfills.

Multifluid models deal with the simultaneous flow

of immiscible fluids in the soil or rock—e. g., a gasoline-water or oil-water model. These models are

similar to unsaturated flow models, except that gasoline rather than air is the second component of

the fluid mixture. Multifluid models can help to

assess the consequences of fuel tank leaks or oil spills

on land.

Contaminant Transport Models

Contaminant transport models analyze the

movement, mixing, and chemical reactions of contaminated water in the native water and the soil

or rock through which it flows. Like flow models,

transport models are also classified by fluid and
w

media types, as well as by the chemical reactions

considered.

Three major processes control the movement and

changes in concentrations of pollution in ground

water: 1) movement due to ground water flow

(called advection or convection); 2) the mixing of

ground waters having different levels of contamination (called hydrodynamic dispersion); and

3) chemical reactions. Contaminant transport

models are normally classified according to whether

they consider chemical reaction. Two major types

of models are generally recognized: 1 ) conservative

transport models, which do not consider chemical

reactions; and 2) nonconservative transport models,

which do.

Nonconservative transport models can simulate

a variety of possible chemical reactions. For example, models may consider the fate of water-borne

pollutants that become fixed or adhere to the soil

or rock surface, thereby coming out of solution and

not moving with the water. However, while these

and more complex reactions can be addressed in

theory, in practice, chemical reactions are normally

either ignored or are approximated by simple equations. Simple equations are used because the precise

mechanisms for the chemical reaction are generally unknown or are too complicated to be used in

field applications.

Data required for both conservative and nonconservative transport models include the hydrologic
146 ● Use of Models for Water Resources Management, Planning, and Policy

..— —

data discussed previously for flow models, as well

as data describing mixing and chemical reactions.

Models generally calculate projected concentrations

of the various pollutants as they vary over time and

space.

Because ground water flow is a major factor affecting the movement of contamination, pollutant

transport models are necessarily extensions of

ground water flow models. As a result, a contaminant transport model is, at best, as reliable as the

ground water flow model to which it is coupled.

For small-scale contamination problems in material

that is highly variable or is fractured, estimates of

ground water flow may be inaccurate, thereby reducing the reliability of transport estimates.

In addition to ground water flow, the movement

of pollutants is affected by mixing and by chemical

processes, both of which are poorly understood.

Since quality problems are more complex than

quantity problems, models dealing with ground

water quality are generally less reliable than those

for ground water quantity. Quality models are also

considered less credible than quantity models because of their recent origin and the relative unavailability of validated models.

Ground Water Quantity Issues

Available Supplies and Optimal Yields

Models are well suited for determining the hydrologic limitations on ground water availability, or

on the yield of an aquifer. Hydrologists have developed several definitions of what constitutes an aquifer’s yield. One definition, “sustained yield, ” represents the maximum amount of water that can be

removed from the system if inputs and outputs are

to be balanced, with no net loss from the aquifer.

The concept is based on the commonsense observation that water cannot be continually withdrawn

from wells if the rate of withdrawal exceeds the

natural rate of replenishment to the ground water

system. A second definition, ‘ ‘optimal yield, incorporates political and social considerations, and

refers to an optimal plan for using a ground water

system, whether on a sustained basis or not. This

approach attempts to maximize economic objectives

and to minimize environmental impacts through

legal and social constraints on the use of the ground

water supply.

Computer models can be very useful tools for estimating an aquifer’s response to alternative development plans. Assuming that the geometry and

water-bearing characteristics of the ground water

system have been adequately described, the modeler uses equations to show, for example, how water

naturally enters the system from infiltration of rainfall or streamflow, how water naturally escapes from

the system through discharge into surface water

bodies or through consumption by vegetation, and

how the extraction of water from wells affects the

overall water balance.

The response of a ground water system depends

not only on hydrological conditions, but also on the

manner in which the ground water is withdrawn

for use. For example, locating wells too close to each

other may cause large water-level declines near the

well field, resulting in reduced yields, dry wells, or

even subsidence of the land surface. Ground water

flow models can be used to address problems such

as the optimal design of a well field and the extent

of available supplies, and to predict water-level declines due to alternative development schemes.

Although the most frequent use of ground water

flow models is for water-supply management, these

models can be helpful throughout the planning

stages preceding management decisions. Models

also provide a framework and guide for collecting

and organizing data. By matching computed model

results with observed system behavior, one can gain

a better understanding of hydrologic and geologic

conditions. Even with limited data, the hydrologist

may use a model to test alternative hypotheses of

how the system behaves.

For managing, regulating, and planning the use

of ground water, models that determine available

supplies and optimal yields are highly reliable.

However, since ground water data are derived primarily from wells, aquifers that are relatively undeveloped often have an inadequate data base for estimating potentially available yields. As the system

is developed, more data become available, and earlier modeling efforts can be modified to reflect this

additional information. Thus, data collection and

modeling activities must be coordinated with aquifer development if reliable information about the

ground water system is to be available when it is

most needed—when water withdrawals are large

enough to significantly affect the aquifer.
Ch. 6—Modeling and Water Resource issues ● 147

Conjunctive Use of Ground and Surface Waters

Aquifers are commonly hydrologically connected

to surface lakes and streams. Ground water frequently provides the base flow to streams—the

streamflow that occurs even during dry weather.

During periods of low rainfall, the base flow provided by ground water is a major determinant of

both the quantity and quality of surface water. A

decline in ground water levels may decrease the

base flow and degrade surface water quality. In

other situations, surface water may recharge the

ground water system. In this case, a change in the

quantity or quality of the surface water would affect the ground water.

Conjunctive use models analyze the interaction

between ground and surface water systems. These

models may provide information about both quantity and quality aspects of surface water and ground

water interrelationships, and can be used to aid in

the combined management of both water sources.

Ground water flow models have been employed for

many different conjunctive-use situations. A typical

problem of this kind involves determining the effects on surface water flows of irrigating with

pumped ground water distributed through irrigation systems. The ground water flow models used

for these applications are essentially the same as

those used to determine optimal yields. For conjunctive use, however, the components of the model

describing the interaction between ground and surface waters become critical and are consequently

more complex.

During the past decade, ground water flow models have frequently been used to solve conjunctive

use problems. Model reliability is nearly as high

as for ground water supply and optimal yield applications; confidence is somewhat reduced, however, because quantitative estimates of the interactions between ground and surface waters are difficult to obtain. Furthermore, the scale of the surface water problem (i.e., area of influence and speed

of water movement) may differ from that of the associated ground water system. This may result in

an accurate description of the ground water response but a less satisfactory description of local

surface water responses.

Subsidence of the Land Surface

Under certain geologic conditions, particularly

where thick beds of clay underlie the land surface,

heavy withdrawals of ground water may lower

ground water levels to such an extent that the clays

partially dry out. In some situations these clays

shrink or compact, resulting in settling or subsidence of the land surface, which may cause ruptures in pipelines, cracking of building foundations,

or even surface water floods. The Houston Ship

Channel in Houston, Tex., is a notable example—

several adjacent residential communities have essentially been abandoned because flooding by tidal

waters has resulted from land surface settlement.

To model these conditions, data are needed not

only for the ground water system itself but also for

soil mechanics and physical properties of clay soils

under dry conditions. In addition, information is

needed about the surface water systems in areas

where subsidence may alter drainage areas and flow

patterns.

Ground Water Quality Issues

A basic understanding of ground water flow is

necessary for understanding ground water quality

problems. Since pollutants entering a ground water

system are carried along with the water flow, many

of the factors that determine quantity relationships

also apply to quality models. Problems of ground

water quality are likely to dominate water resource

issues in the 1980’s. They fall into four broad categories: 1) accidental and negligent contamination

from urban and industrial areas; 2) agricultural

pollutants to ground water; 3) movement of pollutants into and through ground water from waste

disposal; and 4) seawater intrusion.

The disposal of wastes, in particular, involves

major political issues for which the analytical capabilities of models will be useful. Wastes can be disposed of in the atmosphere, in streams and other

surface water bodies, or into or on the solid earth.

Each of these options has associated tradeoffs. Inland and onland disposal of either solids or liquids

may contaminate ground water and cause wastes

to be transported long distances from the original
148 ● Use of Models for Water Resources Management, Planning, and Policy

disposal site. Consequently, ground water hydrologists are being asked to predict the movement of

contaminants to aid in designing waste-disposal

systems to minimize contamination. The problem

is perhaps best exemplified by the present search

for a geologic disposal site for high-level radioactive wastes.

Accidental and Negligent Contamination

From Urban and Industrial Areas

Unintentional ground water pollution is reported

with increasing frequency. Regulatory agencies

have particular difficulty in planning for emergency

incidents of ground water pollution, due to the wide

variety of possible contaminants and hydrogeologi11 - M /

cal conditions. Contaminant transport models, in

conjunction with careful hydrologic studies, can

provide important information on alternative corrective measures.

This section deals with unintentional, nonagricultural contaminants to ground water. Three frequently occurring pollutant types will be discussed:

1) petroleum products; 2) industrial chemicals; and

3) road salts. For each of these, contaminant transport models can be used with varying degrees of

success and confidence. Model capabilities are limited primarily by insufficient data on and understanding of the movement of contaminants through

soil and rock. It is often necessary to drill numerous

sampling wells to determine the extent of the contamination. Other information that is needed includes the amounts of contaminants released and

the chemical reactions occurring in the soil.

Petroleum spills and leaks are serious sources of

ground water contamination. Hundreds of thousands of gasoline storage tanks, thousands of miles

of underground pipelines, and numerous tank

trucks and railroad cars carry oil or gasoline

throughout the country. Contamination from these

sources is quite difficult to analyze with models.

Models of the movement of oil or gasoline have

been routinely employed for petroleum reservoir

engineering, but have had limited application to

ground water problems. Insufficient experience

with these models limits their use for analyzing contaminant transport.

P

Photo credits: @ Ted Spiegei, 1982

Extensive ground water withdrawal can cause land to subside on small or large scales. At left, signs on telephone

poles in the San Joaquin Valley, Cal if., show the sinking of the Earth’s crust as a result of ground water use for irrigation

since 1925. Florida sinkhole at right demonstrates a more dramatic local effect. At any scale, land subsidence in inhabited

areas has enormous destructive potential; developing models to estimate the conditions under which subsidence will

occur requires extensive knowledge of geology, ground water hydrology, and soil sciences
Ch. 6—Modeling and Water Resource Issues ● 149

Although oil and gasoline do not generally mix

with water, small concentrations of petroleum products may dissolve. These low concentrations may

exceed acceptable water pollution standards. The

movement of dissolved oil or gasoline can be analyzed by contaminant transport models once the

nature of the dissolution process is known. These

models can be used to gage the effectiveness of various cleanup procedures.

Toxic industrial chemicals can accidently contaminate ground water supplies in a number of ways—

leaky storage tanks, tanker spills, or leaky holding

ponds. The range of possible contaminants makes

it difficult to use models to predict resulting pollutant concentrations. In general, for chemicals that

dissolve in water but do not react with soil or rock,

credible models can be developed if sufficient hydrologic data exist. However, for chemicals that are

either immiscible with water or reactive with soil

or rock, model reliability will be low, regardless of

the amount of hydrologic data available. Still, for

such reactive constituents, conservative or ‘ ‘worstcase’ predictions can be useful for assessing the

maximum pollution potential, and can be generated

by assuming that no reactions occur. In these cases,

model results can aid in evaluating alternative

remedial measures.

Large quantities of salts are applied to roads during icy conditions, primarily in Northern States.

Road salt is highly soluble in water; thus, shallow

ground water supplies near major roads may become contaminated. In recent years, recognition

of this problem has led to decreased usage of road

salt. While contaminant transport models can assess

the potential for ground water pollution from road

salt use, the problem is not generally considered

serious enough to warrant the collection of the expensive field data needed to produce credible results.

Agricultural Pollutants to Ground Water

Agriculture, because it is so widespread an activity, is an important influence on the quality of

ground water. Agricultural activities can affect

ground water quality through: 1) salt buildup, and

2) contamination by herbicides and pesticides.

Salt buildup is caused in two ways. In semiarid

regions, fields close to streams are commonly irri -

gated with both surface water and pumped ground

water. As the water flows through the ground and

returns to the stream, it accumulates salts from the

soil that are further concentrated by evaporation

from soil and plants. The water returning to the

stream often has high salt concentrations and is

sometimes unusable for irrigation by farmers downstream.

Salt buildup can also occur as a result of fertilizers, and, to a lesser extent, from storage or disposal

of livestock wastes. Fertilizer is a serious source of

pollution. Nitrates—a major component of fertilizer

and a type of salt—are the most common cause of

ground water contamination beneath agricultural

lands.

The use of pesticides and herbicides has expanded

significantly in recent years, When pesticides and

herbicides are applied to the land, they migrate

downward toward ground water supplies through

the unsaturated zone. They generally move slowly, and undergo chemical changes in the unsaturated zone that alter their properties. Pesticides and

herbicides that are “broken down’ in this manner are often not harmful when they reach the

ground water. However, the greater the use of pesticides and herbicides, the higher the likelihood of

producing concentrations exceeding the biodegradation capabilities of the unsaturated zone. Serious

ground water pollution can result in such cases,

Models of ground water flow and transport

through saturated soil and rock are generally

reliable when applied to these problems. Water

quality variations in an irrigated stream-aquifer

system can be reliably predicted with mathematical

models, if sufficient data are available.

Flow and transport in unsaturated zones are less

well understood; consequently, unsaturated flow

models are less reliable than saturated ground water

models. As yet, no model has been developed that

incorporates all the physical, chemical, and biological processes occurring in the unsaturated zone.

However, many problems involving pesticide-herbicide ground water contamination can be analyzed

without a comprehensive model, Simplified models

are useful for assessing the effectiveness of the unsaturated zone as a barrier to potential pollutants.

Results based on conservative or worst-case as-
150 ● Use of Models for Water Resources Management, Planning, and Policy —

sumptions may be helpful for determining the effects of agricultural practices on ground water.

Movement of Pollutants Into and Through

Ground Water From Waste Disposal

Several methods are commonly used for onland

waste disposal:

● landfills;

. surface spreading;

. surface impoundments; and

● injection wells.

Approximately 5 pounds of solid wastes per person are produced daily in the United States. Solid

waste is normally reduced in volume by compaction and placed in landfills, which currently number

over 150,000 in the United States. When rain enters

a landfill and infdtrates through the refuse, byproducts of waste decomposition dissolve in the water,

producing a liquid known as leachate. Leachate can

be a serious problem in nonarid regions, where rising water tables infiltrate refuse, causing contaminants to migrate into the ground water system.

Such leaching of pollutants may continue for decades or even hundreds of years. Models can be used

to predict the effects of alternative engineering

designs on the landfill hydrology, and to predict

the transport of leachate into ground waters. These

models are still in initial stages of development.

Much domestic waste in the United States is

processed in secondary sewage treatment plants.

A common practice for disposing of these waste byproducts is to spray liquid sewage on and spread

sludge over the land surface. Surface spreading of

sewage and sewage sludge may degrade ground

water quality, both through salt buildup and from

heavy metals that are not removed during secondary treatment. Since this practice is similar to fertilization, modeling capabilities and difficulties are

similar to those described for agricultural practices.

Surface impoundments are pits, ponds, and lagoons

in which liquid wastes are stored, treated, and disposed of. These wastes contain a wide variety of

organic and inorganic substances. Over 170,000

impoundments are located in the United States—

many of them contain potentially hazardous wastes.

Few of these impoundments have a bottom liner,

and few have means for monitoring ground water

quality.

Contaminants that seep from impoundments

may be modified in the soil by various chemical

reactions, thus reducing their harmfulness; others

may move into shallow ground water and cause pollution. Studies generally show that ground water

contamination creates a contaminant plume that

may be well contained locally, but might extend

up to a mile or more from the impoundment, depending on ground water conditions.

Actions that can be taken to alleviate contamination

●

●

●

of ground water include:

lining the impoundment with plastic, impervious clay, asphalt, or concrete;

constructing collection systems such as wells

for recycling; and

reducing the movement of contaminated

ground water by means of hydraulic or physical barriers.

The effectiveness of these actions can be evaluated

with mathematical models. The approach to analyzing contamination from impoundments is similar

to that used for landfills.

Wastewater injection wells offer an alternative to

disposal of waste at or near the land surface. As

of mid- 1973, at least 278 industrial wastewater injection wells had been installed in 24 States, and

170 of these wells were operating. Most were between 1,000 and 6,000 ft deep and had average injection rates of less than 400 gallons per minute.

As with other pollution problems, chemical and biological reactions occurring within injection wells are

the most difficult to model accurately. Nonetheless,

models may still be used to estimate the impact of

the injection system on the natural hydrology; this,

in turn, may be used to design well fields and injection schemes.

Seawater Intrusion

Cities in coastal areas often withdraw large quantities of ground water for their freshwater supplies.

This decreases the seaward flow of freshwater,

which may cause saltwater to move into ground

water reservoirs.
Ch, 6—Modeling and Water Resource Issues 151 — —

The movement of seawater into drinking water

supplies in coastal areas is a serious and widespread

problem. Models can aid in designing well fields

and pumping schemes to minimize seawater intrusion. However, for cases in which the hydrology

is complex, such as a layered ground water system

in which flow characteristics among the layers vary

greatly, modeling results are less reliable.

Evaluation of Currently Available

Ground Water Models

In table 9, models that can be applied to each

of the problems previously described are evaluated

according to model types employed and the models’

areal scale of analysis. The evaluations are for the

general level of model development in each category

, rather than for any specific model. A comprehensive list of models available for ground water

analysis is provided by Bachmat, et al. 1

Two major criteria are used to evaluate each

model category: 1) model reliability; and 2) credibility of model results. Models are considered reliable if they can accurately describe the important

chemical and physical processes. Credible results

require both a reliable model and sufficient data

to run that model. For some applications, models

may be reliable, but the cost and difficulty of colIY

. B. Bachmat, et al. , ‘ ‘Utilization of Numerical Ground \\’atcr

Models for Water Resource Management, ” U.S. Environmental Protection Agency, report No. EPA-600 /8-78-Ol 2, 1978.

Table 9.—Ground Water Model Evaluation

spatial Considerations

Model types

Site Local Regional

Transport Transport Transport

Transport WIO Transport WI Wlo

Pollutant movement, if any

WI Wlo

Flow only reactions reactions Flow only reactions reactions Flow only reactions

un

Fiow conditions

sat sat sat multi sat sat : ; t sat sat M sat sat sat sat sat sat sat sat sat sat

P F p fluid P F F’ P F P P F P F p F p F p F

Issues

Quantity—available supplies. . . . . B c A B B B

Quantity—conjunctive use . B R A B B B

Quality —accdental petroleum

products. . . . . . . . . . R B c R c R

Quality—accidental road salt, . . . . B c c

Quality—accidental industrial

chemical . . . . . . . . . . . . . . . . . . . . B c c c R – B c c –

Ouality—agricultural pesticides

and herbicides. . . . . . . . . . . . . . . B c c c R – B c c –

Quality–agriculture salt buildup. . B c c B c

Quality—waste disposal landfills. B c c c R – B c c –

Quality—waste disposal injection. B c c c R – B c c –

Quality—seawater intrusion. . . . . . B B c c 0 c c c

Key

Rows — issue and subissue areas discussed in text

Columns — model types and scale of applications; e g, the sixth column applies to a site-scale problem in which Pollutant movement IS described by a transport

model without chemical reactions under saturated flow condltlon in fractured media

Application scale

Site—models delaing with areas less than a few square miles

Local—models dealing with areas greater than a few square miles but less than a few thousand square miles

Regional—models dealing with areas greater than a few thousand square m!les

Abbreviations

w/—with

w/o—without.

sat—saturated ground waterfiow conditions

unsat —unsaturated flow conditions

P—porous media

F—fractured or solution cavity media

Entr!es

A a usable predictive tool having a high degree of rellablllty and credlb!l!ty given sufficient data

B a reliable conceptual tool capable of short.term (a few years) prediction with a moderate level of crediblltty gwen suff!ctent data

C a useful conceptual tool for helping the hydrologist synthewze complicated hydrologic and quality data

R a model that IS still In the research stage

— no model exists

Blank—model type not applicable to issue area
152 . Use of Models for Water Resources Management, Planning, and Policy

lecting data may prevent calculated results from

being very credible. The ratings assigned for each

model category are a composite of these two considerations.

The key at the bottom of table 9 describes the

terms employed, and briefly summarizes the model

rating scheme, the breakdown of model types, and

the measurements used to define different levels of

scale. Explanations of the rating scheme, and of

scale and time considerations in model evaluation,

are provided below:

Model Rating

A rating of‘‘A ‘‘ indicates that models are reliable and can be applied with credibility to a particular problem. It also implies that data necessary

to use the model can be obtained at reasonable

costs. Models with ‘ ‘A’ ratings can be used effectively for making decisions on applicable problems.

Models rated “B” can be used for short-term

predictions with confidence. The lower level of credibility implies that either some part of the processes

described is not fully understood, or that data necessary to use the model may be too expensive or

too difficult to obtain. These models can be applied

to field problems if their limitations and capabilities

are recognized. Further, if field data were collected

on a continuing basis and incorporated into the

model, model credibility would improve. Models

with “B” ratings can also be used to investigate

general problems (but not specific field applications). Conceptual investigations can be used in

designing regulations and policy, e.g., for determining landfill siting criteria.

Models rated ‘‘C” have not been sufficiently validated for analyzing specific problems. Both expensive data collection and inadequate understanding

of important processes are likely for these models.

Models with “C’ ratings have utility as conceptual tools for investigating general problems.

Models having a rating of “R” are still in developmental research stages. In the future, these models should earn a higher rating as they are validated

through field use.

Models described by “-” are not presently

available.

Area/ Scale. The credibility of ground water

models is highly dependent on the geographic scale

of the study area. Most models are designed to operate at the local scale (area greater than a few

square miles but less than a few thousand square

miles). Therefore, more confidence may be placed

in models used for this scale.

Time Scales. Ground water models project future

conditions for widely varying intervals of time.

Generally, the longer the range of the prediction,

the less reliable it is. Ground water models normally

involve planning horizons of 20 to 30 years, and

each model varies in its ability to forecast future

conditions. For many hazardous waste problems,

the time frames needed are much longer, sometimes

ranging to hundreds of years. Results from such

projections are much less credible than results from

models used for problems with shorter time frames.

While time frames are not specifically considered

in the evaluations, the effects of different time projections on the credibility of model results must be

considered in evaluating specific models.

ECONOMIC AND SOCIAL MODELS

Introduction

Many different types of models and analytic techniques are used to determine the economic and

social consequences of water resource activities, to

forecast consumer and industrial water needs, and

to analyze water resources for comprehensive river

basin planning and management. Social and economic models address patterns of human behavior

using theories drawn from economics, sociology,

social psychology, geography, and political science.

Economic models are used to estimate the overall

effects of water resource activities and regulations

at both the regional and national levels, as well as

to forecast economic consequences to individuals

and firms. For example, an economic model can

forecast changes in an industry’s water use as the
Ch. 6—Modeling and Water Resource Issues ● 153

cost of obtaining water changes, and determine the

effect of such changes on industrial output.

Social models can project population trends, estimate water demands, and analyze the social structure of a given area. They can be used to identify

the groups likely to be affected by resource decisions, and their perceptions of these effects. Social

models can be coupled with economic models to

evaluate the societal implications of water resource

regulations or projects.

The use of social and economic models is relatively new in the water resources field, as in other fields.

Social and economic model use in water resource

analysis has been prompted by two major regulations: 1) the Principles and Standards (P&S) of the

Water Resources Council; and 2) the National Environmental Policy Act of 1969. The P&S are a

group of publications that presently require consideration of the likely effects on environmental

quality and national economic development of projects proposed to receive full or partial Federal funding. The P&S also require studies of the effects of

proposed projects on regional development and on

the social well-being of the affected area. The National Environmental Policy Act requires estimates

of the social and economic effects of proposed projects. To make such estimates, social models can be

used to identify the population that would be affected by the resource decision, and the extent of

the likely effects. Economic models are also employed to determine the economic impacts of a project on individuals, firms and the region overall.

Several factors account for the increasing use of

social and economic models. Models may provide

the only available means of organizing complex information for examining the effects of an action or

policy. Information derived from the conditions and

scenarios assumed in a model can provide insights

about the effects that may occur, and serve as a

basis for common discussion of assumptions and

probable outcomes. Finally, social and economic

models can be used to compare the merits of proposals in terms of a particular objective, and help

decisionmakers determine the costs and benefits of

a proposed decision.

Both social and economic models are limited by

the necessity of dealing with human behavior,

which is not always predictable. Behavior is difficult

to incorporate in a model except in an abstract

way—identifying behavioral tendencies with in a

probability of outcomes. Another problem, more

prevalent among social models, is that they are

data-limited. Available data often prohibit quantifying and analyzing all factors involved in determining the ‘ ‘public interest‘‘ in any given situation.

Thus, ‘ ‘decision’ models of social and economic

factors can only be used as guides—they cannot be

substituted for the human decisionmaking process.

Because of the difficulty in evaluating social science models, and their less advanced state of development, these models were not formally evaluated.

Few social science models are widely adaptable;

moreover, such models are difficult to validate by

comparing predictions to results, as is routinely

done for models of physical processes. Assessing the

relative utility of these models requires comparisons

of previous model applications under a variety of

conditions by different analysts, and necessarily involves a considerable component of subjective analysis.

Basic Analytical Characteristics

Social science models are classified by the kinds

of information they generate. Three major distinctions are used to identify significant characteristics:

1) descriptive v. normative; ‘2) macroscale v. microscale; and 3) efficiency v. distribution of costs and

benefits.

1. Perhaps the most important dimension involves

the distinction between descriptive and normative models. A descriptive model is an empirical

and historical representation of ‘what is. Descriptive models determine factual relationships

as they exist or may be expected to occur. They

are intended to include a minimum of subjective assumptions and biases.

A normative model may be equally reliable and

credible, but it focuses deliberately on ‘‘what

should be. Normative models include substantial judgments and assumptions about goals and

objectives. For example, a descriptive model of

the Nation’s economic output would simply report actual or expected levels of gross national

product (GNP), while a normative model might

include the assumption of a 5-percent annual increase in GNP as an economic goal. Most of the
2.

Photo credit: U.S. Department of Agr/cu/ture

Water resources development can have tremendous effects on an area’s ability to attract residents, industry, and related

activity. Models are available to estimate how construction expenditures may directly affect local or regional economies,

as well as how water facilities could affect subsequent development. In addition, models can describe how waterrelated development could affect demands for a wide range of public services, for example, schools, hospital facilities,

roads, and other infrastructures

current social and economic models used in

water resource analysis are normative, i.e., substantial a priori value judgments have been made

about the goals, objectives, measures, and methods used in the model.

Scale is the second feature by which social science models can be categorized. Two distinct

types are recognized—macroscale models and

microscale models. Macroscale models address aggregate changes or activities. Macrolevel models

include those that measure and forecast trends

such as levels of national economic activity (e. g.,

GNP), money supply, international trade, migration patterns, etc. They are useful for providing national and regional analyses of water

resource projects and programs.

3.

Microscale models focus on individual and/or

enterprise-level behavior. They are often used

in water resources for feasibility studies, environmental impact statements and other project-planning activities. Microscale models are used to

address, for example, pricing, benefit/cost, social

impact, and risk/benefit questions.

A third feature of social science models addresses

the dual questions of efficiency and distribution of

costs and benefits. Water resource policies or activities affect both economic efficiency and the distribution of costs and benefits. Efficiency is describable by economic models, while addressing

the distribution of benefits requires a broader

social analysis, Models of economic efficiency

focus on means of increasing the gross supply
Ch. 6—Modeling and Water Resource Issues ● 155

of goods and services. Distributive models trace

changes in assets and/or income distribution

among either resource owners (e. g., labor, capital, management) or major sectoral groups

(e. g., farmers , industrial workers, the unemployed).

Types of Models Used

for Economic Analysis

Four types of economic models are widely used

for dealing with water resource issues: 1) inputoutput; 2) optimization; 3) econometric; and

4)

1.

2.

3.

simulation.

Input-output models are based on a detailed accounting of sales and purchases among each of

the industries or sectors being studied. Information on purchases and sales is used to determine

either the requirements for particular inputs

(e.g., water) or the production of outputs (e. g.,

manufactured products).

Optimization models are used to determine the allocation of resources that best meets a previously

specified objective (e. g., least cost), subject to

some specified constraints. The technique is particularly well suited, therefore, to solving problems where both the objectives and the constraints are clearly defined. When more than one

objective is considered, these models can describe

the tradeoffs between the best solutions for each

respective objective.

Econometric models are a less homogeneous group

than the two previously discussed classes of models. The term is generally used to describe forecasting models, the structures of which have been

carefully estimated from historical data. The

large, national forecasting models (e. g., Chase,

Wharton, Data Resource, Inc. (DRI), etc. ) are

of this type, as are many models tailored to

regional and State needs. Econometric models

are typically based on the following macroeconomic principles: 1 ) production determines income; 2) income determines demand; and

3) production, in turn, adjusts to demand. The

interactions among production, income, and demand determine economic multiplier effects,

which play an important role in economic impact analysis.

4. The fourth class of models is referred to here as

simulation models. Economic simulation models

are often input-output or econometric models

that are adapted to examine the implications of

different sets of assumptions. Simulation models

describe the highly involved pattern of causeand-effect relationships that operates within most

social or economic systems. Once relationships

are identified and the key factors have been

quantified, the model is used to simulate the

performance of a system over a period of time,

under different sets of assumptions about the

system’s internal relationships and the values of

external variables. Such models can calculate the

incremental effects of price changes or improvements in production methods, for example.

Other Social and Economic

Analytical Techniques

In addition to traditional economic analysis and

the four model types identified above, an increasingly large set of social and economic analytical

methods is being used in natural resource planning

and policy evaluation. The methods are diverse,

so they will be discussed here according to the kinds

of relationships they are designed to explore.

A major consideration in planning and policy

analysis is the size and demographic structure of the

population. Demographic models, therefore, relate

information about the present size and structure

of the population to projected changes due to births

and deaths or to population shifts. Most of these

models deal with specific age, sex, and racial groups

or cohorts, and are consequently referred to as cohort survival models,

Another set of analytical techniques has been developed to deal with the demands for, and supply of

infrastructure—factors such as housing and public

facilities and services. These techniques are used

by planners to determine the fiscal impacts on governments —including both expenditures and collection of revenues—of providing various levels of infrastructure services, Standard models are available

to carry out these infrastructure and fiscal impact

calculations, although variations among jurisdictional units require adjustment for the particular

unit of government being considered.
156 . Use of Models for Water Resources Management, Planning, and Policy

Once economic, demographic, and public sector behavior has been accounted for, a major remaining concern is the social structure of an area. Few

computer models have been developed to analyze

this problem, but progress is being made in defining social structure, and in understanding how it

is affected by natural resource decisions.

The final major area of activity for socioeconomic

analysis is the integration of the various economic

and social concerns discussed above. The models

discussed above provide measures of change in the

economic, demographic, fiscal, and social environment. However, the significance of these changes

ultimately depends on the perceptions and values

of the people who will be affected by them. Current research is underway in identifying groups that

may be affected by resource decisions, and determining their evaluation of the social and economic

changes that may affect them. Methods for quantifying these analyses, however, are in relatively early

stages of development.

Economic and Social Issues

in Water Resource Analysis

Effects of Water Pricing on Use

Severe water shortages in many locations have

prompted investigation into strategies for reducing

the demand for water. Water use restrictions have

commonly been used for managing water use, but

other methods that rely on economic incentives

(water pricing and conservation subsidies) have

potential for reducing the consumption of water

through nonregulatory approaches.

Water demand models, which predict the response of water demand to changes in water costs,

have been developed for residential, industrial, and

agricultural uses. The cost of using water, as considered by these models, includes both prices paid

for water delivery and other acquisition and use

costs, such as costs of disposing of used water.

Residential/ water demand models are based on actual household water use behavior. Consumer demand theory suggests that the quantities demanded

are related to water price, consumer characteristics

(income, family size), and factors such as the

season, and extent of outdoor use. Data are collected on household water use and on factors which

affect that use. Using statistical analyses, the effect of price can be isolated from the effects of all

other variables influencing residential water use.

The models analyze actual consumer responses

to water prices. However, because responses to

prices vary among regions and among income

groups over time, model estimates will be region-,

time-, and income group-specific. These models are

useful planning tools, provided that adequate data

are available and that analysts recognize the theoretical and statistical assumptions underlying the

model.

Industrial and agricultural! water demand can also be

analyzed with mathematical models. Because large

water users are often self-supplied, market prices

for water in the conventional sense do not apply.

However, analyses for these demand sectors are

based on the costs borne for using water. These

models consider the objectives and constraints that

govern agricultural and industrial decisions about

levels of production and amounts of raw materials

to be used, including water. The influence of water

price on use is inferred by examining the models’

predictions of water use changes as water costs

change.

These models are not based on observed responses to price change. Rather, they are simulations of responses that could be expected from ‘ ‘rational’ water users with objectives and constraints

similar to those described in the model. To the extent that water users deviate from the objectives and

constraints assumed in the model, model predictions will be inaccurate. A number of these models

have been developed; however, their use requires

highly skilled analysts and good data bases.

Both types of water demand models are useful

tools for water resource decisionmaking. If properly

developed, they can organize complex information

about the factors that determine water use, and assess the importance of price relative to other factors in determining use. Information provided by

such models is helpful for developing demand management strategies, including changes in prices of

publicly supplied water (e. g., at municipal systems

or Federal irrigation projects) or marketing of water

rights, where market prices are determined by willing buyers and sellers. These models are useful for

comparing alternatives, but are less reliable for pro-
Ch. 6—Modeling and Water Resource Issues 157

vialing quantitative estimates of actual volume demands.

Cost to Industry of Pollution Control

Pollution control costs, like the availability and

cost of water, are one of many factors affecting the

profitability and location of industrial activity.

Models are used to determine the effects of regulations on specific industries, as well as the impact

of pollution control policies on the economy as a

whole. Costs of pollution control can be assessed

at both macroeconomic and macroeconomic levels.

Macroeconomic costs are those associated with a

particular firm or industrial group, and include direct expenditures for pollution control equipment,

costs of changing production processes, and foregone production. Macroeconomic costs are gaged

by calculating the effects of industry expenditures

to meet environmental regulations on employment

levels, the Consumer Price Index (CPI) and GNP.

Macroeconomic models are the most complex of

all economic models. Their development and use

requires highly skilled personnel. For example, the

models of DRI, and Chase Econometrics, Inc.,

which are among the best known of this type, have

been used to evaluate changes in macroeconomic

variables in response to industry expenditures for

compliance with environmental regulations. However, some analysts consider it inappropriate to use

these models to measure ‘ ‘costs of pollution control. While the models can predict movements in

the CPI or GNP, they do not estimate the economic

value of a cleaner environment (e. g., reduced health

care costs, workdays lost due to illness, etc. ) as an

offset to the cost of pollution control equipment.

The reliability of these models is difficult to test;

their use depends largely on the plausibility of assumptions made about inputs and the lack of credible analytical alternatives.

A4zc~oecomrnic moa!ds of costs to industry for pollution control are most often optimization models,

similar to those described in the above section on

water demand. Models of this type can be developed for ‘‘typical firms ‘‘ in specific industries. A

baseline condition is first determined by applying

the model without environmental regulations. Environmental regulations are then introduced as a constraint on the firm’s resources and outputs. Proper interpretation of the results can provide estimates

of the costs that firms incur as a result of regulations. Limitations and potentials of this type of

model are similar to those of water demand models.

Models of this type are used for determining the

least-cost approach to environmental regulations.

These models have been used to a limited extent

by EPA in the water quality regulatory process. It

is likely that greater use of these models will be

made in the future, for reviewing existing or promulgating new environmental regulations.

Benefit/Cost Analysis

Benefit/cost analysis measures the value of a policy, program, project, or regulation in terms of economic efficiency. Procedures for calculating the

benefits and costs of Federal water resource activities are outlined in the P&S of the Water Resources

Council.

A relatively small portion of Federal activities in

water resource protection and development is now

covered by the P&S. Affected agencies (principally the Corps of Engineers, Soil Conservation Service, Bureau of Reclamation, and Tennessee Valley

Authority) prepare estimates of some costs and benefits of their proposed investment projects. However, some of the most common Federal activities

—e. g., waterway and discharge permits, and sewage treatment construction grants—are not required to prepare benefit/cost analyses.

Although economists have developed rigorous

theoretical standards for determining the proper

measure of both costs and benefits, even the most

competent analysts face difficulties in conducting

sound benefit/cost analyses. Many costs and benefits may be known, and yet be difficult to define

or quantify accurately—in water resource activities,

more incommensurable benefits tend to be encountered than incommensurable costs. Construction

costs for building a dam or a sewage treatment

plant, for example, are easier to estimate than the

value of decreased likelihoods of flooding, or the

value of cleaner water to downstream users.

When no professional consensus exists as to the

monetary value of a benefit, or the probable cost

of an activity, standards of accuracy for benefit/cost

analysis are difiicult to establish. Estimating the val-
—

158 Use of Models for Water Resources Management, Planning, and Policy

ue of less tangible benefits necessarily involves an

element of subjectivity; consequently, such estimates are affected by the assumptions of the analyst.

The choice of a particular time frame or discount

rate, for example, while not imparting intentional

bias, may heavily influence results.

As a general rule, benefits and costs of public

projects are easiest to evaluate when the resources,

goods, or services produced are traded in the

market economy (e. g., power production). Benefits

and costs are less easy to measure if the resource,

good, or service either contributes directly to a good

which is traded (e. g., irrigation water as a factor

in agricultural production), or if the private market

offers a comparable substitute for the public project’s output (e. g., railroad transportation as a

substitute for river transportation). Benefits and

costs are very difficult to estimate for resources,

goods, or services for which few market transactions exist (e. g., recreation, wildlife habitat). In

these cases, the economic value of the public project cannot be inferred from observed market prices.

Institutional limitations on the alternatives that

can be considered for achieving an objective constitute another constraint to effective use of benefit/cost analysis for Federal water activities.

Benefit/cost analysis is most useful when it is used

as a screening device for comparing alternatives.

If an agency, for example, is restricted to funding

flood control structures and cannot propose purchasing flood plain development rights as a nonstructural alternative, the full power of the

analytical technique cannot be effectively used.

Benefit/cost analysis is often used to support normative arguments that no actions should be taken

unless benefits exceed costs. However, such arguments are often rejected for two reasons: First, complete measurements of economic efficiency, benefits, and costs of public actions are limited by data

and time for conducting the analysis. Therefore,

a benefit/cost analysis will often not reflect all

economic benefits and costs. Second, economic efficiency in resource allocation is only one of several

possible aspects of the “public interest” which must

guide decisions. For example, the distribution of

these benefits and costs among the public can be

considered as important as the relative amounts of

these benefits and costs. Nonetheless, benefit/cost

analysis is useful for comparing and screening alternatives according to their relative contribution to

the Nation’s economy.

Implications of Water Resources Policy

for Regional Economic Development

The regional economic impact of water resource

development is an important concern that is not

considered in ‘‘standard’ benefit/cost analysis. To

the locality or region in which a water project is

proposed, the regional economic effects may be as

important as the costs or benefits to the nation as

a whole.

Models have been developed that estimate

changes in the level of local or regional economic

activities (employment or income) and/or economic

base (development potential) due to projects or activities. Standard models include various forms of

simple economic base studies, as well as the more

complex input-output models.

In the past decade, advances have been made

in regional development models for analyzing economic, demographic, and community effects associated with water resources development. The Bureau of Reclamation, for example, has developed

the Bureau of Reclamation Economic Assessment

Model, an economic/demographic simulation model used in both planning and impact assessment procedures. Similar tools are used by the Corps of Engineers and by regional and State water resource

agencies.

These models are used to evaluate the economic

effects of direct expenditures made in a region to

implement a program or build a project, and the

continued effects of the spending generated by these

activities. Such models simulate a complex and dynamic process, accounting for multiplier effects

from expenditures made in direct support of the

activity (wages paid to labor, goods and services

purchases locally, etc.), and assist in comparing the

impacts of alternative programs and projects on the

regional economy. Such comparisons can be of value for both planning and policy.

The use of these models is feasible for most skilled

analysts. The Water Resources Council has published multipliers developed by the U.S. Department of Commerce for simulation purposes. How-
Ch. 6—Modeling and Water Resource Issues ● 159

ever, developing the models and multipliers themselves requires special skills and extensive data.

The results of these models must be carefully interpreted. Such models are based on data that represent the existing regional economy. If the water

resource activity being evaluated significantly alters

the region’s economic structure, the model may be

invalid. The smaller the public action relative to

the regional economy, the more reliable model results will be. Moreover, these models should not

be used with the implicit assumption that economic

activity (e. g., a new industry) will be attracted to

the area solely on the basis of increased water resources development. Many economists consider

water projects to be uncertain means for redistributing income, stimulating regional development, or

achieving employment stability.

Clarification of the regional economic stake in

water development has been and can be further

aided by careful model use. This type of analysis

is best suited to planning activities, such as comparing scenarios for different alternatives. If such

models are used to estimate impacts with more precision, they should only assess the impact of certain, direct expenditures resulting from the public

action, and only for short (1- to 5-year) time

periods.

Forecasting Water Use

Models for forecasting long-range water use

range from simple extrapolations of past trends to

complex models that project water use in response

to changing social, economic, and technological

conditions.

Simple models, often termed the ‘ ‘requirements

approach” to projection, have been favored by Federal agencies in the past. These models extrapolate

historical growth rates in water use, by use category

or for total consumption. The models can be modified to provide separate per capita use rates and

population projections, which are then combined

to produce a total water use projection. Under the

latter approach, per capita use is projected to grow

at historical rates and population projections are

taken from separate demographic studies. The requirements approach has been called into question

because it has failed to project actual water use accurately. The requirements approach also provides

little assistance to the decisionmaker, since it does

not indicate why water use changes over time.

To remedy these shortcomings, more complex

economic forecasting models have been developed.

Complex models are simply applications of the

water demand models described above. First, the

demand models are used to determine the relative

importance of the various independent factors

(price, income, technology, etc. ) that determine

consumption levels for each major category of water

user. Second, future changes in these factors are

projected and incorporated into a demand model

to predict future demands for water. A disadvantage of the complex model approach is that it requires projections into the future for many factors,

a difficult task requiring a large, credible data base.

Water use projections are only guides—’ ’best

guesses’ about an uncertain future. The demand

model approach does, however, serve a useful role

in planning and policy. Models can be used to test

the sensitivity of forecasts to different assumptions

—e. g., they can identify

quences of overinvestment

water supply capacity.

Risk/Benefit “Analysis

and assess the conseor underinvestment in

The consideration of uncertainty in planning or

policymaking processes is a significant recent development in water resources analysis. ‘‘Risk assessment, o r ‘ ‘risk/benefit analysis, is required by

the revised P&S for situations in which uncertainty is an essential element of the planning process.

Risk/benefit analysis deals with uncertain events

so as to reflect both the expected outcome (in a

probabilistic sense) and public attitudes toward

uncertainty and risk. Public attitudes are particularly difficult to gage for those situations in which there

are low probabilities of highly serious accidents.

Since the year-to-year and day-to-day variability of the hydrologic cycle encourages the presentation of information in probabilistic terms, risk

analysis is a particularly suitable approach to water

resources decisionmaking. A flood or a drought or

a pollutant spill of a particular magnitude will cause

quantifiable losses. Estimates of the probability of

that size flood or drought or spill occurring transform the projected loss to a statement of risk. Safety

is generally paid for with time and money. Projects
160 . Use of Models for Water Resources Management, Planning, and Policy

and policies, with their associated costs, work to

either reduce damages or the probability of an undesirable event. Judgments about acceptable levels

of risk and what should be spent to reduce them

are a part of the politics of water resources. Models

can help in clarifying those choices.

Risk/benefit analysis organizes information so the

decisionmaker can compare the reduced risk of alternative policies with the increased costs. The

“benefit” side of risk/benefit analysis is generally

a statement of net costs incurred by choosing a more

costly alternative over a less costly one. These costs

are calculated using estimation models similar to

those used for benefit/cost analyses. The ‘‘risk’ side

of risk/benefit analysis is a statement of the probability and consequences of a particular action or

occurrence. Consequently, risk/benefit analysis is

not the sole domain of social scientists, but must

rather be conducted by engineers, lawyers, and scientists from many disciplines.

Methods for estimating adverse health and safety

risks are relatively new, but the cases in which these

methods have been applied are relatively similar.

One of the major shortcomings of this approach is

the inadequacy of historical data to construct probability functions. Although subjective probabilities

can be assigned by experts, such assignments can

potentially impart biases to the analysis. The high

degree of uncertainty about dose-response relationships, in particular, tends to reduce the credibility

of quantitative estimates of risk.

Social Impact Analysis

The potential social impacts of water resources

programs or projects have received increasing public attention in recent years. As a result, Federal

agencies have begun to develop accounting methods

for social-effects that consider two important factors:

1.

2.

The effects of a program or project fall unevenly on different groups. For example, some

groups may benefit from increased employment, some may experience shifts in recreational opportunities, others may undergo tax

increases.

The desirability of these effects will depend

on the value structures of the groups affected.

The impact of activities can be perceived differently by different groups.

These two factors mean that political decisions

are likely to affect certain groups differently than

others. Decisionmakers need to understand not only

the effects of a project, but also what the effects will

mean to the affected individuals.

Regional economic development models (described above) provide a basis for considering community-level effects—particularly effects on housing, on the demand for public facilities and services,

and on the overall fiscal condition of local governments. Once these consequences of a project have

been determined, consideration must be given to

what the Water Resources Council has referred to

as ‘‘social well-being. The remaining questions

are of two kinds: First, what is the effect of the project on the social structure of an area? Second, how

are the economic, demographic, community, and

social effects of the projects perceived by the affected

people? Models and operational methods to answer

these questions are still in the research stage.

Current research indicates that social structure

is definable in terms of: 1 ) the functional groups

in an area; 2) the characteristics of the groups (e. g.,

size, attitudes towards growth); and 3) patterns of

economic, political, and social interaction among

the groups (e. g., employee/employer relations and

political alliances). Questions can then be asked:

Will a project introduce any new groups into an

area? Will it in any important way affect the characteristics of existing groups? Will it affect the way

in which economic, political, or social interaction

occurs among the groups? Answers to these questions constitute the social effects of a project in the

same sense that economic/demographic and community effects can be defined using the models and

procedures outlined above.

The next step in social well-being analysis is to

determine the significance of the changes to the people affected. This requires that the distribution of

effects among the various groups be known and that

their individual evaluations of these effects be determined. Specifying the distribution of the effects

(economic, demographic, community, social) is

usually possible once both effects and groups have

been clearly defined. Effects can then be evaluated,

largely through direct questioning of group members or knowledgeable individuals. This part of the

social assessment process constitutes ‘‘public involvement.
Ch. 6—Modeling and Water Resource Issues ● 161

In projecting the social impacts of various

changes, models can be used to: 1 ) organize information on the social factors that are affected, and

2) qualitatively determine the direction of the impacts (positive, negative, or no change). Even this

qualitative information can be useful to a decisionmaker. If a systematic approach is not used, the

inventory of social impacts may be incomplete.

Unified River Basin Planning and Management

River basin models consider the simultaneous use

of water resources and the competing values associated with those uses. Such models are one means

of assessing the ‘‘value’ of water for alternative

uses—both for offstream purposes and recreational,

wildlife, and water quality instream uses. These

models form an analytical basis for examining alternative planning and management strategies for an

entire river basin. River basin models require input from a large number of disciplines as well as

information from economic and social models.

Two principles are central to unified river basin

planning and management:

1.

2.

River basin planning stresses comprehensive

analysis of the interrelationships among water

resources and social and economic activity,

rather than the project-specific focus of most

planning activities.

River basin planning emphasizes monitoring

and analyses on a continuing basis, instead

of only at times when specific projects are

being considered.

Since the methods applied in this area are similar

to, or the same as, the methods discussed in the

The first models developed for unified river basin

planning were river basin simulation models completed during the 1960’s. These models linked water

resources to economic activity and demographic

trends. The Susquehanna River basin model developed in the early 1960’s was the first of these efforts, and demonstrated the applicability of a systems approach to river basin analysis. The general

example provided by that work has been repeated

many times since.

Another related application of river basin analysis

has occurred principally in the Western United

States. Models have been developed to analyze the

economic development implications of competitive

demands for water among agriculture, energy-related mining or industrial development, and in recreational stream uses. Analysis of the implications

of alternative allocation schemes has generally been

conducted at the river basin or State level, using

simulation models with hydrologic, econometric,

and demographic components. Models of this kind

were first developed for the purpose of analyzing

different resource management strategies in Utah

in the early 1970’s with the Utah Process Economic

Demographic Model. Similar models now exist in

many States and, among other applications, are

used to analyze water resource management alternatives.

Only in a few basins have there been modeling

and data collection on the scale necessary to relate

in detail both water quality and water demand to

subregions and sectors. To do this comprehensively

requires linking physical and social models that include many subjective inputs from citizens and/or

decisionmakers.

previous sections, all of the justifications and limitations discussed in those instances apply here.
Appendixes
Appendix A

Summary of Findings From OTA

Workshops on Water Resource Modeling

During the fall of 1979, the Office of Technology

Assessment held two series of workshops on water resource modeling. The first series, held on October 24

and 25, addressed issues raised by staff members from

21 Federal agencies. The second series, held on November 28 and 29, brought together 37 representatives of

universities and private consulting firms.

The two sets of workshops were identical in organization and operation. During the first day, both sets considered problems in model development and application; on the second day, they considered problems in

model management and in the use of model results. Participants in each workshop were divided into four topical

discussion groups: 1) surface water flow and supply;

2) surface water quality; 3) ground water; and 4) economic and social factors. Each group, on each day it

met, identified a list of problems that emerged during

the day’s discussion, and then used an idea-writing session to develop solutions to the problems identified.

This appendix synthesizes the results of the two sets

of workshops. Because many of the same problems were

raised and discussed across topical groups and in both

sets of workshops, results will be summarized by problem area. Concerns or suggestions specific to one of the

series or to a topical group will be so identified.

Research and Development (R&D)—

Specific Areas

Participants in each of the four topical discussion

groups identified several specific research needs within

their assigned areas. These needs are summarized below.

Surface Water Flow and Supply

Participants identified the following uses as research

priorities:

● Online operations of water supply systems. Models

need to be developed to aid managers in determining current operating rules on the basis of present

and historical flow and demand conditions.

● Prediction of regional low flows and droughts.

Models for stochastic analysis of regional hydrology

need improvement.

Surface Water Quality

Participants in both workshop series placed high priority on two major research categories: 1 ) erosion and

sedimentation; and 2) the fate and transport of toxicants.

For the first category, Federal participants suggested

several specific areas requiring model development:

● Erosion models that predict the outcome of management alternatives, such as deforestation.

 Models that determine the fate of chemicals before

they reach the stream system.

● Physically based models for sediment detachment,

transport, and channel erosion. Empirically based

models are currently being used.

● Sediment transport models linked with ecosystem

models.

Participants agreed that improving the current state

of knowledge about toxicants is urgently needed before

better models can be developed to help in complementing major regulatory programs. Federal participants emphasized the need to improve understanding of:

● transport mechanisms;

● the long-term fate of toxic materials; and

● the effects of toxics on biological organisms and

communities.

Federal personnel identified two further categories requiring research: reservoir and river mixing; and nonpoint source pollution. The group considered the first

topic a high priority because reservoirs and rivers are

receptors of toxics, and because mixing is an important

component of sediment transport.

Nonpoint source pollution was considered to be increasingly important, as control of this problem becomes

more cost effective than controlling point source pollutants. Specific model needs include:

nonpoint source models that include toxics as wel]

as sediment runoff;

models to predict reductions in nonpoint source

loadings due to various control strategies;

models that translate nonpoint source loadings into

water quality and ecological impacts; and

models that qualify loadings under event-oriented

conditions rather than on an annual basis.

Ground Water

Both series oi workshops advocated R&D of models

to analyze flow through aquifers that are difficult to

165
166 ● Use of Models for Water Resources Management, Planning, and Policy

characterize. The private sector group specifically identified flow through fractured rock as a research need;

one Federal participant gave the example of radioactive waste disposal assessment as an application in which

ground water flow is a highly important component.

Understanding the transport of chemicals through

ground water in order to assess concentrations of contaminants was also identified as a research priority by

both workshop groups. Specific suggestions included:

. improving the numerical accuracy of ground water

transport models;

. incorporating chemical reaction terms into transport models; and

. researching the capability of aquifers to naturally

cleanse themselves of pollutants.

The private sector group unanimously suggested that

the Government sponsor research at specific waste disposal sites. Members suggested that this research be part

of a national program to deal systematically with production, processing, and disposal of potentially hazardous waste.

Economic and Social

Federal representatives considered interregional microeconomics to be a research priority. Participants disagreed about both the adequacy of economic theory and

the availability of data to describe interregional economic effects. Private sector modelers focused on intraregional concerns; specifically, developing methods to

analyze the distributional implications of water policies.

They pointed out problems of cost and availability for

obtaining comparable data on a regional basis, and

problems of determining the proper structure of models—e. g., the proper level of geographical aggregation,

and assigning relative weights to social, economic, and

environmental concerns when characterizing the effects

of water resource activities.

R&D—Methods

Two major themes emerged from workshop discussions about modeling methods: 1 ) improving and characterizing predictive capability; and 2) integrating alternative methods and improving their ease of use.

Methods to Measure Uncertainty

Participants in the private sector workshop stated that

research on quantifying the uncertainty of predictions

is needed. Specifically, they suggested that improved,

standardized methods need to be developed and adopted

for assessing the total uncertainty in model outputs due

to errors in data, sampling, model parameter estimation, and calculation. Knowledge of risks policy makers

would most like to avoid would also aid in designing

methods for reporting uncertainties.

Federal participants in the area of ground water modeling identified a need to improve parameter estimation

and methods for incorporating uncertainty into stochastic models. They suggested: 1) that parameter estimation procedures allow for interaction with the user to

permit initial estimations, and to constrain the range

of values being generated; and 2) that uncertainty of

input and its impact on reliability or confidence in output always be considered during an analysis, to increase

the utility and aid in the acceptance of ground water

models.

Risk Characterization Methods

The surface water flow and supply group in the

private sector placed high priority on two items:

developing methods to characterize both long- and shortterm risk in water systems, including reservoirs; and

conveying the concept of risk to the public. One participant noted that risk is relative, and asserted that

modelers should therefore determine the cost of not

meeting some requirements when judging risk and its

impacts. Another participant argued that this approach

would result in guessing with computer models, which

he considered less reliable than experienced judgment.

The Federal surface water flow and supply group focused on the relationships between extrapolation techniques and risk characterization. The group identified

a need to improve techniques for extrapolating shortterm simulation results for long-term implications.

These extrapolation techniques are critical for extending

the use of available data bases.

Predictive Capability

The surface water quality group from the Federal

workshop recognized a need to make ecosystem models

predictive at higher trophic levels. Participants stated

that development of predictive models appears stalled,

even though the techniques are within the state of the

art. Recently developed theory has not yet been incorporated into predictive models.

-The same group identified a need to improve predictive capabilities and procedures for dealing with ‘ ‘nonpredictive’ events. One participant suggested linking

stochastic models with physical models to generate long

time-series of simulated ‘ ‘data, which, along with

probability analysis, could help improve predictive capabilities, Probabilistic models could also be coupled with

or used as complements to parametric and deterministic

models.
App. A—Summary of Findings From OTA Workshops on Water Resource Modeling ● 167

The surface water quality group was also concerned

over the need to improve current capabilities to model

transient effects.

Model Integration and Coordination

In the private sector workshops, both the surface

water quality and economic/social groups focused on the

need to interrelate different types of modeling capacities.

Participants in the surface water quality group stated

that research should be done on methods to improve

compatibility of components of water quality models.

The major components of these models—sources of materials, transport to and within receiving waters, and

processes occurring within receiving waters—are modeled individually and independently, often at different

times and space scales. Research is needed to make the

individual components compatible over the longer time

and larger space scales needed for effective water quality

models.

Private sector economic/social modelers suggested the

need for methods to integrate their work with physically

based models.

Higher Dimension Models

The need for two- and three-dimensional models for

rivers and other water bodies was mentioned by the surface water quality group. One view was that for planning or screening alternatives, one-dimensional models

are often, though not always, sufficient. For design purposes, two- or three-dimensional models are frequently

important.

Participants suggested developing a research program

to determine the type of models needed for different

types of problems—relating the dimensionality of the

models to different water bodies and pollutants.

Methods To Improve Model Use

Workshop participants suggested several R&D areas

that might result in more efficient and productive uses

of models. These include:

. using models that address a wider range of ahernatives— this is of primary importance in economic

models;

developing more efficient analytical methods to reveal sensitivity relationships to the user; and

 developing improved model calibration methods,

including automated and user-interactive methods.

Finally, members of the private sector surface water

flow and supply group suggested that standard, accepted

models for routine tasks be identified and made available. In addition, they advised that standard computer

programs be designed that include a set of random numbers already specified for comparative and reporting

purposes.

Data

One of the major concerns of both Federal and private

participants was that data are not available to develop,

calibrate, validate, and apply models. Federal modelers

identified the intensive data needs of complex models,

the cost of data collection, and the lack of coordination

and planning of data gathering as major reasons for the

unavailability of data.

Private participants tended to agree that the datagathering process should be related more directly to the

needs of models. Some suggested that modeling should

precede and guide data gathering. Federal participants

stressed the need for model developers to be more sensitive to the potential data requirements and data costs

of their models, and suggested that data collection occur

concurrently with model development.

Federal participants also agreed that improved datacollection techniques are needed to facilitate more economical data acquisition. Some participants expressed

a need for greater attention to the design of data networks. Private modelers felt that the problem of inadequate data often arises because Congress and governmental agencies are unwilling to conduct data collection and review programs. Participants noted that many

model types continue to be developed without adequate

data to support them. They felt that certain model types

should not be developed without commitments to related

data-gathering activities. However, private sector participants noted that if data collection is not funded, regulations will need to be designed to accept qualitative

or semiqualitative solutions.

To improve data availability, Federal participants

suggested that developers, users, and data gatherers

should: 1) share data and identify cooperative data

needs; 2) perform sensitivity analyses to identify the

most critical data needs; and 3) develop mechanisms to

identify and collect long-term data. They also stressed

that continual reprogramming of research funds often

causes long-term data needs to be neglected.

Existing Data Bases

Federal participants felt that it would be cost effective to spend additional time analyzing existing data

bases. The surface water flow and supply group suggested that better agency coordination is needed to consolidate existing data bases. The group recommended

that data base management specialists be employed to

manage agency and interagency data systems.
168 Use of Models for Water Resources Management, Planning, and Policy

National Data Bank

The private sector group held extensive discussions

on the need for a national data bank. Speaking against

the idea, participants stated that data banks in general

are not desirable because data collection should be done

with specific model formulation in mind. People in the

ground water group wanted a standard data base developed for independent model comparisons. Suggestions

for groups to manage a data bank included the Environmental Protection Agency (EPA) laboratory at Ada,

Okla., or the Holcomb Research Institute, with funding

by EPA. Some people in the surface water group wanted

a national data base to supply consistent, experimental

data for establishing the interrelationships between

quantity and quality parameters. In the economic/social

group, some members felt that an agency similar to the

Census Bureau should be established to obtain reliable

and consistent water resource data.

Documentation

Federal and private sector modelers strongly believed

that inadequate documentation restricts the wide use of

good models and contributes to the misuse of models.

Participants agreed that the inadequate allocation of

resources for documentation and the lack of incentives

to promote good documentation greatly contribute to

the problem.

Federal participants suggested the following remedies:

● Assign responsibility for documentation to an organizational unit to ensure that adequate resources

are allocated. This unit might also handle technology transfer, users’ assistance, etc.

● Provide incentives to modelers to allocate time to

documentation efforts.

● Establish minimum guidelines for documentation.

Private sector participants tended to advocate more

prescriptive approaches. They asserted that agencies

should demand acceptable model documentation of all

models developed with public funds. As an added incentive, agencies might withhold a percentage of the project costs until adequate documentation is received. Currently, they complained, Federal agencies such as the

Office of Water Research and Technology and the National Science Foundation may end funding before the

documentation project is complete.

Federal participants specified two separate components for adequate documentation: 1) a technical document; and 2) a users’ document. A separate programmers’

document and an executive summary document were

suggested by a few participants. In the private sector

groups, suggested components for complete documentation of a model included: user’s manual; capabilities and

limitations (including explicit acknowledgments of the

failure to model phenomena that are not well enough

understood to be modeled); case studies and examples

representing previous successes and failures; references

to literature citations and names of people and organizations who have used the model; operation costs; personnel requirements; and a program listing and computer

requirements.

Validation/Credibility

Federal participants identified the lack of model validation as one of the most important problems in water

resource modeling, and discussed three major factors

contributing to the problem.

First, resources are not adequately allocated for model

validation because of its high costs. These costs might

be reduced if interagency cooperation increased (e. g.,

cooperative interagency sampling and funding arrangements).

Second, the lack of necessary data for validation requires attention. The cost of data collection, the absence

of historic data, and the time necessary to collect validation data are all limiting factors.

The third factor was the absence of guidelines for validation, identified specifically by the surface water flow

and supply group. A majority of the group supported

guidelines, while recognizing that guidelines would be

difficult to establish because of the diversity of model

designs and applications. A lead agency might be given

responsibility for suggesting appropriate guidelines.

The private sector groups advocated establishing appropriate incentives for validation. Other suggestions

from the private sector focused on specific procedures

for model validation, requiring sensitivity analyses on

all analyses made, and requiring followup investigation

where model scenarios have been implemented.

Participants from the private sector also felt that models should be subject to peer review. They suggested that

agencies contract for intensive review in key project

stages, such as definition, completion of model development, and review of results.

Technology Transfer and Training

The majority of participants in the Federal workshop

considered improving technology transfer to be a top

priority; private sector participants agreed that appropriate technology transfer and Federal agency policies

on technology transfer do not currently exist.

While most Federal participants believed that responsibility for technology transfer lies with the model developer, they also recognized that agencies need to provide adequate resources for technology transfer programs. They suggested that proper allocation of re-
App. A—Summary of Findings From OTA Workshops on Water Resource Modeling “ 169

sources might be expedited if responsibility for technology transfer were given to a lead agency. Modelers from

the private sector suggested that for agencies currently

without technology transfer mechanisms, either in-house

development or outside contracting would be appropriate.

Private sector participants tended to focus on training in specific disciplines and related model use as an

important component of technology transfer. Participants mentioned the federally supported university

training grant programs in environmental pollution and

environmental health (now discontinued)—a comparable training program in water resources is needed

today. They felt that funding universities to transfer new

developments to the agencies should continue.

Participants from Federal agencies made a number

of suggestions regarding particular methods of accomplishing technology transfer. Most agreed that the most

important mechanism is one-to-one interaction between

the user and the developer. For example, developers

might be temporarily assigned to a user’s organization

to assist the user, and in addition, provide feedback for

the developer. Using a central technical support staff

to help solve operational problems was also suggested.

Workshops that give participants “hands on” interaction with models, and seminars, were considered good

transfer techniques, especially if the developer is directly

involved. Workshops and seminars designed for different levels of users (e. g., managers, technical specialists,

modelers, and laymen) were also deemed necessary.

Generally, Federal participants believed that agencies need to develop incentives for developers to invest

time in technology transfer activities. Many acknowledged that current agency career evaluation systems

discourage modelers from providing adequate technology transfer.

Model Maintenance

Both Federal and private workshop participants

strongly believed that adequate model maintenance is

essential for effective model use. Private sector participants specified that Federal funding should be provided

to support model maintenance and updating, but differed in their views on appropriate institutional arrangements to provide such support. Proposals included:

●

●

●

designating a lead agency to track and disseminate

Federal model information and revisions;

requiring the sponsoring agency itself to maintain

and update the model; and

having the agency provide funds to the developer

(or other outside group) to maintain and update

models.

Federal participants proposed several specific methods

to improve model maintenance:

establish minimum guidelines and standards for

model maintenance;

prepare a written plan for long-term maintenance

and assurance of adequate resources to undertake

such maintenance. Year-by-year requests are inappropriate;

assign responsibility for model maintenance to an

organizational unit and assure that appropriate resources are available to carry out this goal. This

group might also be responsible for model documentation, user assistance, and technology transfer; and

establish an interagency clearinghouse to conduct

a periodic survey of models, and to update and/or

revise model components as needed.

Clearinghouse

Perhaps the most controversial of the subjects addressed at the workshop series was the concept of a clearinghouse for information on available models. Most participants in the private sector agreed on the utility of

some form of a model clearinghouse; Federal modelers

in the surface water quality and surface water flow and

supply groups classified the concept as one of their 15

priority categories. The latter groups stated that a clearinghouse or inventory is needed to aid technology transfer and to serve as an information source for effective

planning for future model development.

In the Federal workshop, the clearinghouse concept

was conceived as having various possible levels of operation. At the simplest level, a periodic inventory might

be established—e. g., a central catalog of models by subject area, listing available models, the agencies that use

the model, and a contact person or agency. While such

an inventory might be adequate, it would likely be difficult to administer.

A fully established clearinghouse could offer several

extra services. The participants felt that responsibility

for the clearinghouse should be assigned to either an interagency group or a particular agency. The clearinghouse could assist future model development by acting

as a focal point for the questions of both developers and

users. It could help to isolate needs for cooperative studies and determine areas of duplication.

Some Federal participants felt that technical literature, conferences, and professional meetings could adequately serve the same function. Other participants

strongly believed that these mechanisms were not sufficient, partly because some operational agencies seldom

publish their modeling efforts. Additional skepticism was
170 . Use of Models for Water Resources Management, Planning, and Policy

expressed about the cost effectiveness of the clearinghouse approach.

Private sector modelers who opposed the idea asserted

that it might cause centralization, resulting in red tape,

regulation and ineffective action; and siphon limited

funding that could be better spent elsewhere.

Coordination

Participants in both sets of workshops concurred on

the lack of coordination of resources and information

for model development among Government agencies.

Private sector participants, while dismissing the issue

of duplication as a minor problem, proposed better regional and interagency cooperation to improve coordination. Federal modelers noted the lack of mechanisms

to promote interagency efforts, and the absence of incentives or precedents for agencies to work together.

Federal participants suggested a number of mechanisms for improving interagency coordination:

●

●

●

a national clearinghouse and periodically published information directory to provide users with

information about the quality, availability, and

characteristics of models;

an interagency model development review committee. This responsibility might be assigned to an existing committee. Some participants felt that the

committee should have only an advisory role, fearing infringement on agency and scientific freedom;

and

a centralized source of expertise to advise on interagency data base creation.

Questions arose as to the practical value of some of

the suggested mechanisms in view of the diversity of

agency needs. Coordinating efforts through interagency meetings were considered to be too broadly philosophical to aid with actual development. However, participants recognized the importance of avoiding new

model development when an existing model can be modified to serve the same purpose.

Educating Managers and

Decisionmakers

The need to educate management and decisionmakers

to the capabilities, assumptions, and limitations of models was stressed by participants in both workshop series.

Private participants emphasized the importance of demonstrating to managers/decisionmakers that models are

simply tools that provide information and insight, rather

than solutions. Federal modelers were concerned about

the loss of credibility suffered by models as a result of

poor user understanding. They noted that users’ lack

of understanding of key concepts leads to model misuse

and distrust of good models. User understanding was

considered especially important for economic models,

because they cannot be easily validated. In this case,

it would be very important for the user to understand

model construction in order to have confidence in the

model.

Workshop participants felt that managers/decisionmakers must be provided with the following information:

●

●

●

●

the underlying conceptual basis of models (rather

than detailed mathematics);

a taxonomy of resource models matched to a corresponding taxonomy of resource problems;

the relative uncertainty of different models’ results;

and

alternative ways to use models to solve ‘‘ realworld’ problems.

Responsive Model Selection

and Development

Federal and private sector modelers concurred in considering the selection and development of inappropriate

models a major problem, and in the need for modelers

to pay greatest attention to policymakers’ needs and objectives in selecting/developing appropriate models. One

participant estimated that 75 percent of all models are

created without a suitable set of specifications defined

by the problems toward which they are directed. Federal

participants further emphasized the need for users to

understand their own needs and the limitations and

assumptions of the models they consider.

Users often want quantitative answers to specific

management questions and issues. However, according

to Federal participants, the users may be unsure of what

information is necessary or may perceive that models

have greater capabilities than they actually do. In general, good documentation can help users understand

model capabilities. The participants suggested several

specific mechanisms to help users gain a better understanding of what models exist and how these models can

be used to solve specific problems:

● Summary documents listing models available in

each agency. These documents would briefly describe operational and developmental models and

their assumptions, capabilities, limitations, appropriateness for specific applications, and the developers’ names and phone numbers. These documents could stress the specific questions that available models can address.

● Seminars for users in each agency on state-of-theart modeling efforts.

A final recommendation from private sector modelers

was that repeated interaction between modelers and pol-
App. A—Summary of Findings From OTA Workshops on Water Resource Modeling ● 171

icymakers is necessary to respond to new objectives and

problems suggested by model results. Federal participants suggested a number of specific mechanisms for

accomplishing these interactions. To develop generalpurpose models, the participants recommended using

modern group management techniques to solicit the

needs of potential users. For more specific models, improved communication between users and developers

was considered necessary. Several participants suggested

predevelopment working sessions to help modelers determine users’ needs and help the users understand what

models can provide.

Legal and Regulatory Problems

Problems mentioned by conference participants from

the private sector in this category ranged from legal liabilities associated with the use of models to interjurisdictional disputes over model use. Participants suggested

that agency contracts be more specific concerning the

legal liability of the model developer.

Conflict among Federal, State, and local decisions

based on the use of different models was also considered.

Communication and cooperation among agencies, including joint model development, was suggested to alleviate these problems. However, participants also noted

that different and conflicting laws, delegations of authority, and organizational interpretation of laws and models

contribute to interjurisdictional disputes.

Participants from the private sector emphasized that

regulations should not require specific methods. Many

thought that models used in regulatory applications

should stress objectives, not specific methods. Others

thought that models used in regulatory applications

should be required to undergo peer review and validation. Another suggestion was to establish a continuously

reviewed listing of models appropriate for certain regulatory applications.
Appendix B

Summary of Model Use by

Individual Federal Agencies

Introduction

This appendix summarizes water resource modeling

activities of Federal agencies, using information supplied

by the agencies and reviewed by OTA contractors and

staff. The information was obtained from three sources:

participants attending an OTA workshop, selected interviews with agency personnel, and a survey requesting

agencies to indicate their model use under specific water

resource laws. Agency representatives to the OTA workshop on Federal agency model use provided OTA with

a written description of their agency’s model use and

model documentation, when available. Further information about model use and model documentation was obtained through selected interviews with agency personnel. The survey yielded information on legislationrelated model use in Federal agencies as of June 1980,

for agencies and ofllces in existence at that time (see survey form, attachment II).

This appendix describes, by agency, the water resource programs in which models are used and the types

of models generally employed. The summary table of

agency model use (table B-1 ) provides an overview of

the water resource modeling activities of most of the

agencies discussed in the text. The 33 water resource

issues used to construct the table are listed in their unabbreviated form in table 1 of chapter 2. References for

the text are listed by agency in attachment 1.

U.S. Department of

Agriculture (USDA)

Economics and Statistics Service (ESS)

ESS provides economic projections of short-term and

long-range agricultural demands for land and water resources. Its analyses focus on how alternative development of such resources could affect the agricultural and

related sectors of the economy. ESS responsibilities include basinwide and interregional economic aspects of

comprehensive river basin planning.

ESS is involved in programs under the Federal Water

Pollution Control Act of 1972 (Public Law 92-500), as

amended by the Clean Water Act of 1977 (Public Law

95-217, hereinafter referred to as the Clean Water Act);

the Soil and Water Resources Conservation Act (Public

Law 95-192, hereinafter referred to as the Resource

Conservation Act); and the Water Resources Planning

Act (Public Law 89-80). It uses models in each program

area.

Under section 201 of the Clean Water Act, which

deals with construction grants for treatment plants, ESS

has used models to assist local groups in Pennsylvania

in choosing among alternatives for treatment facilities.

ESS also uses these models as part of its own general

research and development effort. For its programs in

areawide waste treatment management planning, under

section 208 of the act, ESS has developed a large policy

model to evaluate alternatives for improving water quality in the San Joaquin Valley in California. Among the

factors the model considers are land-use options, zoning, and application of irrigation water. ESS uses models

under section 209 of the act as well, which addresses

nationwide river basin planning. Models are also used

to determine the minimum cost of comporting sewage

sludge in evaluating different projects under section 405

(disposal of sewage sludge) of the Clean Water Act.

ESS is also involved with regional or river basin planning under section 102 of the Water Resources Planning Act. The service uses models to estimate economic

impacts of section 102 programs (regional or river basin

plans). The models help project future economic conditions in rural areas under various scenarios. As is the

case with all USDA river basin studies, these studies

are carried with the cooperation of local sponsors.

In planning conservation programs under section 6

of the Resource Conservation Act, ESS uses models to

project the likely effects of different economic conditions

and conservation programs on land and water use, on

erosion, and on the national economy.

ESS develops and applies computer programs for such

other agencies as the Soil Conservation Service, the Water Resources Council, and the Environmental Protection Agency (EPA). These models generally incorporate

economic criteria and are often of the optimizing or

prescriptive type. An increasingly important service of

ESS is to maintain the Land and Water Resources and

Economic Modeling System (LAWREMS) described in

chapter 4 of this report. This directory aids communication and technology transfer among agencies in

order to reduce duplication in model development.

LAWREMS contains models and data sets developed

and maintained by ESS and other agencies and nongovernmental bodies.

172
App. B—Summary of Model Use by Individual Federal Agencies ● 173

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174 ● Use of Models for Water Resources Management, Planning, and Policy

Forest Service

The Forest Service is responsible for developing, managing, and protecting lands in the national forest system.

Its objectives include fostering multiple use and sustained yield of forest and rangeland resources. Beyond

its research and data-gathering functions, the Forest

Service coordinates planning for the forest~ component

of river basin surveys and investigations, as well as for

the small watersheds program under the Watershed Protection and Flood Prevention Act (Public Law 83-566).

It is also responsible for managing flood plains and protecting wetlands on national forest system lands.

The Forest Service carries out a large number of programs authorized under water-related legislation, and

uses models in connection with many of these programs.

These include:

Under the Clean Water Act:

● section 107—mine-water pollution control;

. section 208—areawide waste treatment;

● section 209—river basin planning;

. section 303—water quality standards and implementation plans; and

. section 3 14—clean lakeso

Under the Endangered Species Act (Public Law

93-205):

● section 7—minimizing impacts of Federal activities

modifying critical habitats.

Under the Surface Mining Control and Reclamation

Act (Public Law 95-87):

. section 506—surface coal mine reclamation permits; and

● section 51 5—environmental protection performance standards for surface coal mine reclamation.

Under the Resource Conservation Act:

● section 5 —collection of data about soil, water, and

related resources; and

. section 6—soil and water conservation programs.

Under Executive Order No. 11988:

. sections 5 and 6—flood plain management.

Under the Water Resources Development Act of 1974

(Public Law 93-251):

● section 73—planning nonstructural measures.

Under the Flood Control Act of 1936 and amendments (33 U.S. C. 701, et. seq.):

. sections 1 -3—choosing and designing flood control

structures.

The Forest Service provided detailed information on

models used under the Forest and Rangeland Renewable Resources Planning Act of 1974, as amended (Public Law 93-378). Under this act the Forest Service creates and implements long-range land and research management plans at local, regional, and national levels.

Models are used to estimate changes in water quality

and supply under alternative management practices,

and to project the economic effects of such management

practices on localities. Models also aid in determining

National Forest Management Act regulations—the

models are used to analyze potential standards and

guidelines and compare results of their applications.

Under planning activities mandated by the Forest and

Rangeland Renewable Resources Act of 1978, the Forest Service uses models to compute soil moisture and

streamflow in forests and rangelands. Information on

soil moisture is used to determine whether and when

to plant trees, and to determine viable levels of livestock

per acre of rangelands. The effects of timber harvesting

on streamflow are evaluated using water yield models,

which determine the maximum levels of harvest consistent with preventing excessive peak flows in rivers. Models are also used to determine harvest designs which increase the water yield in watershed areas.

Science and Education Administration (SEA)

SEA is actively involved in water resources modeling as part of its mission in natural resources research.

The agency’s water resource modeling activities embrace a wide range of topics: climate and weather, the

hydraulics of overland and channel flows, rill and interrill erosion, sediment yields from agricultural watersheds, infiltration, evapotranspiration, irrigation scheduling, subsurface drainage, and the transport of agricultural chemicals, among other topics.

In its program under section 208 of the Clean Water

Act, SEA uses models to estimate the effects of landuse practices on agricultural nonpoint source pollution.

This information is made available to USDA ofilces and

to the public through USDA technical assistance programs. The agency also uses water resource models in

the agricultural research it conducts under section 1402

of the Food and Agriculture Act of 1977 (Public Law

95-1 13). Models are used to predict the effects of different land-use practices on agricultural and nonpoint

source pollution.

SEA extramural funds are used for scientific research

at universities to assist in developing water resource

models for resolving local, State, and regional water and

water-related problems. The research may produce

components and mathematical techniques for use in developing models or in checking the scientific validity of

models. SEA scientists coordinate these research efforts

among the respective States and the intramural research

programs of SEA. In a number of cases, State and Federal scientists are cooperating on the same regional project, working on mutually developed objectives, and

sharing ongoing research progress at least annually.

For the most part, SEA’s modeling program aims to

improve understanding of the fundamental physical,

chemical, and biological processes that control or con-
App. B—Summary of Model Use by Individual Federal Agencies . 175

strain crop production; assist resource conservation; and

reduce present or future impacts of agricultural activities

on the environment. In selected areas such as erosion

and nonpoint source pollution, model development has

reached the point that applying the models to resource

management, planning, and policymaking is considered

both feasible and justified. Examples of these models

are the Universal Soil Loss Equation (USLE) model,

and the Chemicals, Runoff, and Erosion from Agricultural Management System (CREAMS) model.

Soil Conservation Service (SCS)

SCS is authorized to develop and carry out a national

soil and water conservation program in cooperation with

landowners and operators and local, State, and Federal

agencies. Its programs assist farmers, ranchers, and

State and local organizations to prepare plans for resource management, including structural and nonstructural improvement for flood protection, water conservation, use and disposal of water, agricultural pollution

control, environmental improvement, and rural community development.

SCS has a background of mathematical modeling dating back to the 1950’s. It has applied models to flood

and irrigation water control and to erosion and sedimentation problems. The principal physical models deal

largely with hydrologic phenomena: generation of hydrography; flood routing; calculation of areas, elevations, and frequencies of floods; and the mechanics of

irrigation. One model is devoted entirely to applications

of the universal soil loss equation, although this functional relationship also appears in many other models.

Recently, several models for economic evaluation

have been developed. In fact, approximately one-half

of the 30 models SCS currently uses are physical/economic integrative models that serve as planning tools

to help evaluate and select conservation strategies. They

are used, for example, to project floodwater damage to

urban and agricultural areas, and the costs and benefits

of various cropping, conservation, and land-treatment

methods.

SCS reported model use under a number of legislative

mandates. Under the Rural Development Act of 1972

(Public Law 92-419), the agency uses models to assist

qualified local sponsors in initiating and sponsoring resource conservation and development areas.

Through the Watershed Protection and Flood Prevention Act (Public Law 83-566), SCS has primary responsibility for USDA’s cooperation with local organizations

in small watersheds throughout the Nation, and has specific responsibility for flood prevention measures. To

carry out these responsibilities, two types of models are

used—a management information model and models to

determine the effects of water quality projects. The first

type is a System of Watershed Automated Management

Information (SWAMI), used to evaluate present programs and assess needed changes.

SCS river basin and area planning activities use models for planning and evaluating the physical, environmental, and economic aspects of water resources. Most

activities include an inventory of existing resources,

projections of future resource uses, and the evaluation

of alternatives. Some studies develop specific models to

represent unique physical processes where no existing

model can be used.

Other programs involving model use that are authorized

●

●

●

●

●

●

under water-related legislation include:

The Rural Clean Water Program (Public Law

96-108), which uses models to evaluate the quality

and quantity of runoff from agricultural watersheds

and to evaluate alternative systems of best management practices.

The Resource Conservation Act (Public Law

95-192), under which models are used to predict

the effects of conservation programs on erosion

rates and land and water use.

The Clean Water Act (Public Law 95-217; sec.

208j), under which models are used to determine

the effects of conservation practices on nonpoint

source pollution from agricultural land.

The Colorado River Basin Salinity Act (Public Law

93-320), under which models are used to determine

the effects of irrigation practices in specific areas

on salinity levels in the Colorado River Basin.

The Flood Control Act of 1950 (Public Law

81-516), under which models are used to select and

design floodwater-retarding structures built under

this authority.

Floodplain Management (Executive Order No.

11988), under which models are used to delineate

flood plains and to predict the river stage effects

of different levels of flood plain encroachment.

Department of Commerce

National Oceanographic and Atmospheric

Administration (NOAA)

NOAA uses models extensively to support its numerous activities under current water resource legislation.

Under the Clean Water Act, for example, NOAA’s activities in basin planning, secondary treatment re

-

quirements, water qualty standards, standards for

pretreatment of toxic effluents, and clean lakes (sees.

219, 301, 313, 307, and 314, respectively) all involve

some model use. NOAA also uses models in its soil and

water programs under the Resource Conservation Act

and in its programs under the Water Resources Planning Act.
176 ● Use of Models for Water Resources Management, Planning, and Policy

Information from NOAA models is also supplied to

Federal agencies concerned with fish and wildlife habitat

protection under the Fish and Wildlife Coordination Act

(16 U.S.C. 661). These models help project effects on

fish and wildlife habitats when planning or evaluating

projects. NOAA also uses models under sections 101

and 102 of the National Environmental Policy Act

(Public Law 91-190). Models are used to estimate effects on instream flow, evaluate effects on habitats and

on an ecosystem’s trophic relationships, and predict the

probable dispersion of an oil spill.

NOAA’s hydrologic service programs are managed

by the National Weather Service (NWS) under authority of its Organic Act ( 1890) and the Flood Control Act

of 1936($ 1,2,3j, 15 U.S. C. 313, 33 U.S. C. 706). NWS

is responsible for issuing weather and river forecasts and

warnings. Federal, State, and local agencies rely heavily

on NWS for river and flood information for management planning, and for probable maximum precipitation estimates used in designing river and flood control

structures. NWS hydrologic forecasts are important for

reservoir operations, water supply management, navigation, irrigation, power production, recreation, and water

quality management. Most of the information supplied

is output from models.

The agency’s concentrated ongoing effort to implement a system of interrelated mathematical models and

predictive techniques is known as the National Weather

Service River Forecast System (NWSRFS). The system

incorporates models already in use and new hydrologic

forecast techniques. Included are models of snow accumulation and ablation, soil moisture, streamflow routing, and unsteady open channel flow. The system also

includes programs for handling and processing data and

for model calibration and verification. Planned additions

to NWSRFS are an enhanced reservoir operation model, and an extended streamflow prediction technique for

water supply forecasting based on a conceptual watershed model. The extended streamflow prediction technique will eventually complement the current water supply forecasting procedures, which are based on statistical

methods.

The first version of NWSRFS was implemented in

1971 and used for river forecasting in the lower Mississippi River basin. When fully implemented, NWSRFS

will be used by all 13 NWS River Forecast Centers

(RFCS) in preparing daily streamflow forecasts for more

than 2,500 river forecast points and drainage areas covering approximately 97 percent of the United States.

Department of Defense

U.S. Army Corps of Engineers

The Corps of Engineers is authorized to investigate,

develop, conserve, and improve the Nation’s water and

water-related land resources. Its programs include planning and development activities for protecting navigable

waters, flood control, hydroelectric power production,

flood damage reduction, flood hazard information,

urban land drainage, wastewater management, shore

and beach restoration and protection, fish and wildlife

conservation, outdoor recreation, aquatic weed control,

and environmental protection. These responsibilities include consideration of the economic, social, and environmental impacts of public works alternatives.

The Corps’ mandates are based on a wide variety of

water-related legislation and many are carried out with

the use of models. Under the Clean Water Act, the

Corps uses models to help evaluate costs and designs

for water treatment facilities proposed for Federal funding pursuant to section 201 of that act. The Corps also

uses models under section 1444 of the act (Federal facility pollution control).

The Corps employs models in its water resource planning activities. It uses models in its regional or river

basin activities under section 102 of the Water Resources

Planning Act (Public Law 89-80) and in planning and

evaluating nonstructural measures under section 73 of

the Water Resources Development Act (Public Law

93-251).

The Corps makes major use of models in connection

with its flood control and management function. Models

are used in designing and selecting flood control structures to be built pursuant to the Flood Control Act and

in planning or evaluating flood-control projects. The

models help assess flood peaks, compute water surface

profiles, and supply data for flood damage assessment.

The Corps also uses models to assist the Federal Insurance Administration in conducting flood insurance studies under the Flood Control Act.

The Corps’ flood plain management programs under

Executive Order No. 11988 also make use of models.

Models are used to delineate the 100-year flood plain

so that Federal and non-Federal interests may comply

with current regulations. For example, one regulation

requires that flood plain encroachment should not result

in an increase in water surface elevation of more than

1 ft. The models help predict the relationship between
App. B—Summary of Model Use by Individual Federal Agencies ● 177

extents of encroachment and the rise in surface water

surface elevation.

The Corps’ research and development in water resource modeling focuses on solving field problems. In

hydrologic analysis, the Corps’ Hydrologic Engineering Center (HEC) has developed a number of computer

models for evaluating the expected magnitude and frequency of runoff from urban and nonurban watersheds.

The principal urban runoff models are HEC-1 and

STORM. HEC models have also been used to improve

the operation of reservoirs during floods. Both HEC and

the Corps’ Waterways Experiment Station (WES) have

developed several models relating to river mechanics.

These models simulate hydrodynamic and sediment

transport processes in rivers, lakes, and estuaries. The

Corps’ WES and the Coastal Engineering Research

Center (CERC) have also developed and applied various

models to compute hurricane surges and wave heights

for design and planning purposes.

HEC has developed two reservoir-system analysis

models: HEC-3 and HEC-5. These are multipurpose

reservoir operation models used in planning and operating reservoir systems for flood control, hydropower,

and water supply. The models have been used at the

planning level to evaluate the water-supply performance

and hydropower potential of existing and proposed reservoirs, and to study flood control. The HEC-5 model

is currently being used in operational studies of hydropower sites selected from the Phase I screening of the

National Hydropower Survey. The Corps also uses

models to assess the potential impact of a partial or complete dam failure.

Both HEC and WES are developing water quality

models. These models are applied to proposed Corps

projects to predict overall water quality conditions and

to develop appropriate design and operational criteria

for attaining desired water quality levels. Models are

also used to evaluate design of operational modifications

for projects in which water quality problems exist.

The Corps’ water resource planning models focus on

flood control. Flood-damage computation procedures

are part of several of HEC flood forecast and control

models. These procedures evaluate the expected damage

from a series of flood events, with and without various

proposed management measures. An optimization routine in the HEC-1 model analyzes various sizes and

combinations of flood-control measures and allows for

the evaluation of tradeoffs among facilities, performance, and cost. The HEC interactive nonstructural analysis model focuses on analyzing and formulating flooddamage reduction measures other than traditional construction projects.

Department of Energy (DOE)

Office of Environmental Assessments

Within the water resources area, DOE’s OffIce of Environmental Assessments is concerned with the impacts

of energy technologies on water resources, including the

effects of energy-related pollutants on biological systems.

The office is also involved in defining water and land

resource requirements for energy technologies including

coal gasification, coal liquefaction, uranium enrichment,

geothermal development, small-scale hydroelectric development, enhanced oil recovery, and shale oil production.

The majority of the water resource models DOE uses

are deterministic simulations of physical systems, and

they deal primarily with three subjects: assessing surface water supply related to the potential for energy

facilities development; analyzing energy-related environmental impacts including thermal effects and transport of various pollutants; and determining the economic and social effects of water use for energy development,

The Ofllce of Environmental Assessments uses several

water resource models. The Water Assessment System

(WAS), located at Oak Ridge National Laboratory, is

used principally for large-scale regional impact assessments. This model projects variations in streamflow,

water use, and water availability over time to assess

water availability for various energy scenarios. The basic

geographic unit is the Water Resources Council (WRC)

aggregated subregion (ASR) level. In support of

WAS, the Automated Downstream Accounting Model

(ADAM) calculates cumulative water availability and

consumption data for surface streams in hydrologic

sequence.

The Water Use Information System (WUIS) of Hanford Energy Development Laboratory is used for a number of DOE assessments. This is a computerized information system containing comprehensive data on water

resources, on water availability and quality, and on electrical generating plant characteristics and operational

characteristics relating to water use. Its basic geographic

resolution is the WRC cataloging unit. The Los Alamos

Coal Use Modeling System (LACUMS) incorporates

water supply and demand sectors into a linear programing model of energy supply to facilitate water- and

energy-related policy analysis. Water S UPP IY is ac

-

counted for by coal demand regions.

For large-scale water quality impact assessments,

Argonne National Laboratory has de~eloped the Argonne Water Quality Accounting System (AQLJAS), a

new regional screening model. The model utilizes
178 ● Use of Models for Water Resources Management, Planning, and Policy

streamflow data, measured water quality data, and residual discharge data at the accounting unit level to estimate changes in concentrations of selected pollutants.

These several models are used by other agencies and

organizations within and outside of DOE.

The Strategic Environmental Assessment System

(SEAS) is not a water resource model per se, but it calculates wastewater residuals and regional water use for

energy scenarios during the course of general environmental assessments. DOE has supported Fish and Wildlife Service development of an instream flow calculation system to quantify the effects of water consumed

by the energy industry and to determine the effect on

aquatic species, habitat, and the like. Its purpose is to

estimate instream flow requirements that might constrain energy development.

Aquifer modeling, though not a major program, is

being developed to investigate the migration of pollutants, particularly radioactive materials, from wastedisposal sites. Energy storage in aquifers has also been

modeled to determine geothermal reservoir dynamics

in support of this energy source. Other models investigate the effects of thermal energy releases on localized

meteorology —including effects on rainfall and cloud formation—which could influence water supply.

Federal Energy Regulatory Commission (FERC)

FERC in DOE uses models under two major programs of the Federal Power Act (16 U.S.C. 803(f)):

Dam Safety and Headwater Benefits.

A number of models are used to plan or evaluate projects under the Dam Safety Program. Some determine

water surface profiles and downstream water velocities

resulting from a dam break. Other models are used for

preparing flood hydrography, reservoir routing, and design analysis.

Payments under the Headwater Benefits Program are

determined with information provided by models. These

models are used to determine the energy gains at downstream hydropower plants resulting from the operation

of headwater reservoirs.

FERC also indicated model use for its cooperative activities program under the Water Resources Planning

Act, and for its participation in planning Federal water

resources projects under the Flood Control Act of 1936

and amendments. Models are used to plan, evaluate,

and review projects, and for data acquisition, statistical

analysis, and water resources/hydropower system analysis.

Department of the Interior

Bureau of Land Management (BLM)

BLM is responsible for managing, conserving, and

developing 174 million acres of publicly owned land in

the 11 Western States and an additional 162 million

acres in Alaska, BLM also administers the subsurface

minerals underlying approximately 370 million additional acres throughout the Nation managed by other

agencies or owned by private citizens, and on the 1.1

billion acres of Outer Continental Shelf owned by the

Federal Government.

BLM’s use of computer-based resource models is occasional, and is confined to selected models for sitespecific analyses. Stochastic hydrologic models are used

to evaluate alternate grazing systems in preparing grazing environmental impact statements. Hydraulic models

are used to evaluate instream flow needs for adjudicating

water rights, designing fishery habitat improvements

and water facilities such as dams and water distribution systems, and in analyzing overburden materials

associated with surface mining. In addition to these

models, BLM uses technological guidelines developed

through the use of hydrologic models to analyze various

resource problems, including timber harvesting and

planting techniques and their impacts on water quantity and quality; fishing improvements associated with

spawning areas; flood plain identification; soil erosion;

analysis of potential mineral leasing tracts; and the siting

of campgrounds associated with water-based recreation.

BLM currently contributes financially to research

within USDA and the Department of the Interior, as

well as to various university investigators. These research projects are expected to produce a series of water

resource models that will be used on a continuous basis,

and to develop an additional technological guideline to

address routine multiple-resource problems. In addition,

BLM expects to continue to use models developed by

others for solving problems related to public lands.

Bureau of Mines

The Bureau of Mines’ principal responsibilities are

to develop mineral resources, promote mine safety, and

maintain healthful working conditions and environmental quality in the mineral industries. The bureau is concerned with the quality of water discharges in all phases

of mineral production, and it engages in research to develop and improve mining technology, including meth-
App. B—Summary of Model Use by Individual Federal Agencies ● 179

ods of protecting water resources used or affected by

mining.

The bureau uses models in two of the programs it carries out related to the Clean Water Act, section 107,

which authorizes mine-water pollution control demonstration projects. Models are used to predict the effects

of iron ore mining in the Mesabi Range of Minnesota

on the area’s hydrologic system. Another program involving model use is designed to develop management

practices to minimize water quality problems during and

after open pit mining of copper ore in Arizona. The information these models generate is furnished to mining

companies to help them comply with mine-water pollution regulations.

The bureau also uses models in several other programs concerned with the effect of mining on water

quality. These programs stem from various acts dealing with water resources:

Under the Safe Drinking Water Act (Public Law

93-523), section 1421 —the bureau has used models

to help predict the effects of surface coal mining

on the ground water regime of western Tennessee.

This information is made available to mine operators to aid them in complying with existing regulations.

Under the Surface Mining Control and Reclamation Act, section 515—the bureau is using models

to predict the effect of coal mining on hydrologic

regimes in Coshocton, Ohio.

Under the Resource Conservation Act, section 6—

the bureau uses models to predict the effects of coal

mining on the hydrologic system, particularly

ground water, in the Power River Basin in Wyoming. This information is also made available to

mine operators to assist them in preparing EISS,

and in complying with regulatory standards set by

different agencies. This work is also related to the

Surface Mining Control and Reclamation Act.

One Bureau of Mines model, UNSAT2, is used to

predict seepage patterns and quantities from mine-waste

impoundments. Applications of this model include analyses of the stability of spent oil shale deposits and the

flow of leachates into ground water systems.

Office of Surface Mining

The Office of Surface Mining administers portions

of the Surface Mining Control and Reclamation Act,

using models in connection with several of its programs

under title V of the act—Control of the Environmental

Impacts of Surface Coal Mining.

Section 515 authorizes environmental protection performance standards for surface coal mine reclamation.

The office and its contractors use models in assessing

the cumulative effect of surface coal mining on an area’s

hydrologic regime to determine regulations and standards for protecting water quality and quantity. This

information is provided to State and local agencies and

to private sector interests. Under section 510 of the act,

the office uses models to evaluate permit applicants’

assessments of the hydrological consequences of their

proposed mining activities, and as a basis for approving or denying permits. The office aiso uses models to

evaluate protection of the hydrologic balance under the

environmental protection standards set pursuant to section 515 of the Surface Mining Control Act.

Office of Water Research and

Technology (OWRT)

The principal functions of OWRT are to improve

technologies and methods for addressing water resource

problems, train water scientists and engineers, coordinate water research, and disseminate water resource information. These tasks, carried out under the State Institute Program by university water resources research

institutes in each State, are aimed at resolving local,

State, and regional water and water-related problems.

The State water resources research institutes and the

State Institute Program are described in detail in chapter

4 of this report.

Because OWRT is not a mission-oriented agency, it

does not itself use water resource models. It is active

in funding model development, however. Water resource models developed by OWRT grantees and contractors span almost the entire range of issue areas and

model uses. At present, OWRT is assessing the need

to develop simpler, less data-intensive models than those

that now exist. A concomitant concern is to adapt existing models to specific applications.

Fish and Wildlife Service

The primary responsibilities of the Fish and Wildlife

Service consist of conserving and protecting fish and

wildlife resources and ensuring their equal consideration with other aspects of water development planning

as required by the Fish and Wildlife Coordination Act

(16 U.S.C. 661). The service has a vital interest in water

and related land-use programs, including diversions,

impoundments, facilities development, and streamflow

regulation. The service participates actively in studies

leading to the formation of national, regional, or river

basin plans for using water and related land resources.

The service uses models in several of its programs

concerned with managing water resources for the benefit

of fish and wildlife. When asked to analyze construction projects and alternatives proposed by other agencies in EISS, the service uses models to project the relative impacts of the proposed construction and its alter-
180 ● Use of Mode/s for Water Resources Management, Planning, and Policy

natives over a number of years. Models also help determine the potential effects of a project on endangered

and threatened species, as well as on water flow requirements for these species. The service also uses models

in surveys and investigations of the fish and wildlife impacts of water resource projects under the Federal Reclamation Act (43 U. S.C. 421 and 422), dealing with irrigation distribution systems and construction of small

water resource projects, respectively.

The Fish and Wildlife Service uses models for several

purposes in its programs in accordance with the Fish

and Wildlife Coordination Act. Under this legislation

the service recommends modifications in project design

and operation consistent with sound wildlife management principles.

Some of these uses are:

●

●

For water resources planning: the service uses

models to help assess water availability and instream flows, to predict the effects on habitats surrounding such projects, and to assess the impacts

of water development projects.

For operation and management activities: the service uses models to help determine waterflow regimes and how to mitigate impacts from construction projects.

The service also acts in an advisory capacity to State

and local agencies that use models to assess instream

flow needs and the effects of construction and energyrelated activities on aquatic populations.

For evaluating the effects of powerplant design and

siting, the Fish and Wildlife Service principally uses two

types of models. One type includes fairly large simulation models for investigating and predicting physical impacts of powerplant operation (specifically, cooling) on

the aquatic environment. Such impacts include fish

entrainment-impingement, as well as habitat modification. The service also uses a Multiple-Objective Programing (MOP) model to study regional alternatives

for powerplant location. The regional energy location

model (RELM) was recently modified to incorporate

biological/ecological considerations into an economic optimization model. This modified model is intended to

include ecological criteria in siting decisions at the

earliest possible planning stage, thus reducing the likelihood of expensive litigation over the development of

future energy resources.

Bureau of Reclamation

The Bureau of Reclamation is involved in developing water and related land resources in the 17 Western

States. Planning such development is a multiobjective

and multipurpose activity directed at irrigation, municipal and industrial water supply, hydroelectric power,

flood control, navigation preservation, propagation of

fish and wildlife, outdoor recreation, drainage, pollution abatement, water quality control, streamflow augmentation, watershed protection, and erosion control.

All the bureau’s water and land resource development

activities are authorized under the Federal Reclamation

Act (43 U.S.C. 421).

During the last 15 years, considerable attention has

been directed toward developing and managing Western

resources. As a result of this attention, a large body of

water-related legislation has been passed that relates to,

and has some impact on, the basic water and land resources development mission of the bureau. Sections

208, 209, and 303 of the Clean Water Act require the

bureau to consider areawide wastewater treatment facilities and management, river basin planning and management, and quality standards and implementation in

plans, respectively. The National Environmental Policy

Act of 1969 in section 102 requires evaluation of impacts from water resource development projects both

during construction and for the long term.

The Colorado River Salinity Control Act was established to define and implement effective salinity control

measures to meet established water quality standards.

Other legislative acts affecting the bureau’s water resource development activities include: the Endangered

Species Conservation Act; Executive Order No. 11988,

sections 2 and 3 (flood plain management); the Water

Resources Development Act, section 73, (nonstructural

measures); and the Flood Control Act (building flood

control structures).

To assist in accomplishing its basic water and land

resource planning, development, and management mission, the Bureau of Reclamation has developed several

water resource-related models. These models are used

in the planning, design, and operational phases of the

agency’s mission, and are employed extensively to evaluate the effects of planned actions as they relate to and

affect the legislation described previously. These models

were not developed for any specific legislation or as a

result of it, but are used as tools to assess the impacts

of planned actions or change in operating strategies to

see how they relate to and comply with the various statutes.

The bureau uses physical/ecological ground and surface water models, as well as various economic/social

models. All of the bureau regional offices and many

of its project offices use surface water models. These

models are usually developed or adapted by the office

using them. Most of these models are project-specific,

and simulate project operations over various time periods and with various hydrological inputs. The models

are used for single projects, multiple projects, or entire

river basins. Model applications include developing reservoir operation strategies; hydropower simulation; and
App. B—Summary of Model Use by Individual Federal Agencies ● 181

water quality, water rights, water availability, and flood

control studies.

The bureau uses models to help determine how temperature changes or peaking power releases resulting

from various reservoir operation, release, and withdrawal schemes would affect downstream fisheries and recreation and power users. This information is communicated

to States, localities, and other Federal agencies so that

reservoir operations can comply with State and Federal

fish habitat temperature guidelines, optimize power generation, and meet water user contract agreements.

Models are also used to evaluate the impact of reservoir and stream operations on fish habitat and populations.

The bureau makes extensive use of simulation models

to evaluate the impacts and effectiveness of irrigation

systems. The models provide information for determining whether projects should be modified to exclude lands

that irrigation would affect adversely. They are also used

to help predict the quality and quantity of irrigation

return flows and the effects of project development on

aquifer quality, receiving stream quality, and chemical,

physical, and biologic properties of project soils. The

Return Flow Quality Simulation model has been used

to calculate salinity and other ground and surface water

quality changes from major irrigation projects in California, Colorado, and the Dakotas. This model can also

be used to schedule the timing and amounts of water

required for a variety of crops and climates.

Models are used in developing salinity level standards and in evaluating the effects of specific actions on

salinity levels in the Colorado River Basin. Specifically, the models estimate the effect of future water uses

on salinity and the cost effectiveness of salinity control

measures for meeting established standards. The models

also help determine the technical feasibility of proposed

salinity control measures at point, nonpoint, and agricultural sources. In addition, the models are used to

develop operating strategies for reservoirs, determine

the optimum size of desalting plants and reservoirs, and

maximize the water supply for all competing uses, including power, municipal and industrial, irrigation, instream flows for fisheries and recreation, and water quality.

Other types of surface water models used by the bureau include unsteady flow routing models to predict

outflows and downstream routings of floods from hypothetically breached dams. These models assist in developing maps of expected inundation areas for emergency

preparedness planning. The bureau also employs and

continues to develop synthetic models to describe extreme storm precipitation and meteorologic conditions.

These are used to determine maximum probable flood

values for sizing spillways and to describe atmospheric

modification potential for precipitation augmentation.

The bureau also uses a wide variety of ground water

models in water resource planning, system design, and

project operation. With few exceptions, these are theoretically based models that simulate the movement of

both water and solutes.

A major recent effort by the Bureau has been to develop and implement the Bureau of Reclamation Economic

Assessment Model (BREAM), a simulation-type model.

BREAM’s basic function is to provide a systematic,

theoretically sound approach to projecting population,

employment, and income. The bureau envisions using

BREAM principally for alternative futures analyses,

public involvement, projection of municipal and industrial water requirements, and economic/demographic

impact assessments related to water resource construction activities and long-run uses and outputs of water

resource development. The economic and demographic

outputs of BREAM are also major inputs and driving

variables necessary for evaluating the social impacts of

water resource development activities. The bureau uses

other economic models to analyze and optimize farm

enterprises in determining irrigation benefits and payment capacity, and to analyze hydropower additions to

existing power system networks.

The bureau has also developed data management and

scheduling systems based on models of management

functions. These provide for scheduling program activities, and funding and manpower requirements.

U.S. Geological Survey (USGS)

USGS conducts research on the physical features of

the Nation, including its mineral and water resources.

This research is based on the fields of hydroloW, geology, geochemistry, and geophysics, and aims at developing new technologies and methods for appraising and

conservin g minerals and water. The Water Resources

Division of USGS is responsible for investigating and

appraising the source, quantity, quality, distribution,

movement, and availability of both ground and surface

water. The legal authority for this work stems from the

act of October 2, 1881 (25 Stat. 505, 526), augmenting

the organic act establishing USGS in 1879, and has been

reinforced by the general language of annual appropriation acts for the Department of the Interior since 1894.

AIso, USGS has been the indirect recipient of program

responsibilities under many different water resource laws

that are primarily directed toward resource management

agencies.

USGS uses models in connection with many of its

programs. Models are used to study flow, ion transport,

and geochemistry in aquifer systems; information thus

generated is made available to Federal and State agencies, and to the general public. Modeling activities of

the USGS Water Resources Division—in particular, the
182 ● Use of Models for Water Resources Management, Planning, and Policy

Federal-State Cooperative Program—are described in

detail in chapter 4 of this report. Models are used in

connection with USGS activities relating to sections of

the Clean Water Act, namely:

● section 201 —grants for construction of treatment

plants;

. section 3 I l—oil and hazardous substances liability;

. section 3 14—clean lakes;

. section 3 16—thermal discharges and exemptions;

and

. section 404—guidelines and permits for use of

dredge or fill materials.

USGS also develops models for use by itself and

others in programs under the Resource Conservation

and Recovery Act (Public Law 94-580).

USGS develops models to study many aspects of quality in selected rivers of the United States. These models

analyze flow and transport, dissolved oxygen, and thermal discharges. Use of these models is generally related

to provisions of the Water Resources Planning Act,

which requires a continuing study of the adequacy of

the Nation’s water supply. USGS is also developing

models that will be used to assess the impact of surface

coal mining on the hydrology of mined river basins, an

activity relating to section 515 environmental protection standards under the Surface Mining Control and

Reclamation Act.

USGS is also concerned with flood control and uses

models in connection with its activities under the Flood

Control Act and sections 2 and 3 of Executive Order

No. 11988, dealing with flood plain management.

USGS models determine flood discharges for specified

recurrence intervals, flood profiles, and flood routings.

The information the models produce is available to appropriate Federal, State, and local authorities and to

the public.

In addition to these uses of models, USGS indicated

that it uses or is developing models in connection with

its activities under the following acts:

● The Safe Drinking Water Act (Public Law 93-523):

— section 1421—protection of underground

sources of drinking water; and

— section 1444—special study and demonstration

project grants for wastewater reuse, reclamation, and recycling processes.

 The Surface Mining Control and Reclamation Act:

— section 506—surface mining permits; and

— section 5 15—environmental protection standards for reclamation.

● The Resource Conservation Act:

— section 5—data collection about soil, water, and

related resources;

— section 6—soil and water conservation programs.

● The Water Resources Development Act of 1974:

— section 73—nonstructural measures.

● The Federal Reclamation Act:

— 43 U.S.C. 421—irrigation distribution systems.

USGS has made significant contributions to the development of models for analyzing ground water problems.

Specific areas include: physical characteristics of ground

water flow, effects of ground water depletion on surface

lands, flow in coupled ground water/stream systems, integration of rainfall-runoff basin models with soil moisture accounting and aquifer-flow models, interaction of

economic and hydrologic considerations, prediction of

pollutant transport in aquifers, and estimation of the

effects of development schemes for geothermal systems.

USGS is actively involved in updating and improving

most of these models.

USGS surface-water modeling efforts include: flow

routing in streams, estuaries, lakes, and reservoirs; sedimentation; transport of physical, chemical, and biological constituents; coupled stream-aquifer flow systems; physical hydrology for rainfall-runoff relations,

stream simulations, channel geometry, and water quality; statistical hydrology for synthetic streamflows,

floods, reservoir storage, and water quality; management and operations problems; and water quality problems that result from environmental pollution, such as

thermal loading, pesticide pollution, and freshwater

eutrophication.

 Independent Agencies

Council on Environmental Quality (CEQ)

CEQ has responsibilities for national overviews of

environmental quality conditions and trends. To satisfy

these responsibilities, CEQ with the cosponsorship of

other agencies and organizations, has developed the

UPGRADE computerized environmental analysis system. This system of models and data bases is used to

analyze water quality, air quality, environmental health,

and socioeconomic data. The system permits cross-analysis (e. g., water pollution vs. health) at the county level.

It is an interactive system and is completely Englishlanguage prompted. Data bases on wide-ranging subject areas are being added to the system in order to

broaden and deepen the system’s analytical capabilities.

Environmental Protection Agency (EPA)

The responsibilities of EPA include establishing and

enforcing environmental standards, conducting research

on the impacts of pollution and ways to control it, and

assisting CEQ in developing and recommending to the

President new policies for protecting the environment.
App. B—Summary of Model Use by Individual Federal Agencies ● 183

With respect to water resources, EPA is concerned with

providing water supplies that are adequate in quality

for all beneficial purposes. The following EPA offices

indicated use of water resource models in connection

with program responsibilities.

1. Office of Research and Development (ORD)—

ORD is actively involved in developing and using water

resource mathematical models and predictive techniques. The major thrust of its modeling activity is to

develop capabilities to translate water quality standards

into maximum allowable pollution loadings, select the

most cost-effective combination of controls, and assess

environmental risks associated with production, transport, use, and disposal of toxic chemicals. ORD has conducted special studies of the Great Lakes, Chesapeake

Bay, James River, and other areas where other EPA

offices have requested technical assistance.

Two principal types of models have been developed

as part of the ORD Great Lakes program. The first,

a series of physical/ecological models, focus on the relationship of phytoplankton biomass to nutrient loadings. These models were developed to understand and

control accelerated eutrophication in portions of the

Great Lakes; they are being used to recommend guidelines for nutrient discharges. The second type of model

describes the transport and fate of toxic pollutants introduced into the Great Lakes, in order to determine

the levels of control required to keep environmental risks

within acceptable levels.

ORD has also developed nonpoint source, toxic pollutant, eutrophication, and circulation models for the

Chesapeake Bay. These address the problems of accelerated eutrophication in portions of the bay, the decline

of submerged aquatic vegetation, and associated impacts

on aquatic life and commerce.

ORD assists EPA’s operational programs in selecting

and using models to deal with specific problems. These

models include urban and rural runoff models and receiving-water quality models. The models are used in

determining control requirements to be placed on discharges and in planning studies required under section

208 of the Clean Water Act. ORD also provides technical assistance with the Exposure Analysis Modeling System (EXAMS), a major mathematical model for assessing the primary pathways, persistence, and fate of toxic

organic chemicals in freshwater systems.

Future water resource modeling needs ORD is addressing concentrate on providing the capability to assess

environmental risks associated with toxic chemicals in

ground and surface water, and identifying cost-effective

pollution control measures to attain and maintain water

quality goals.

2. Office of Water Regulations and Standards

(OWRS)—EPA’S OWRS uses some models in developing guidelines for toxic and pretreatment effluent

standards pursuant to section 307 of the Clean Water

Act. The models OWRS currently uses address three

main problem areas: the fate of pollutants discharged

into receiving waters, and their effect on water quality;

the quantity and quality of runoff from urban and agricultural areas, and its impact on receiving waters; and

the economic effects of water pollution regulations on

industries.

A principal model in the first category is EXAMS.

The Water Quality Analysis Branch of OWRS currently

uses EXAMS to evaluate different control strategies for

selected pollutants in order to determine whether these

pollutants should be subject to best available technology

(BAT) requirements or to more stringent controls. The

EXAMS model is being used in conjunction with agricultural runoff models, such as ARM-II, and receiving-water quality models, such as QUAL-H, for screening analyses of new pesticides.

Another major use of models of this type is in establishing and enforcing wasteload allocations for National

Pollutant Discharge Elimination System (NPDES) permits. These models are used to assess the assimilative

capacity of a water body and to relate stream water quality levels to pollutant discharges. The models are also

used to determine whether dischargers are complying

with permit allocations.

OWRS’S Office of Analysis and Evaluation assesses

the economic impact of water pollution regulation on

industrial sectors by one of two techniques, depending

on industry size. For small industries, the office performs

industry-specific financial analyses to determine if compliance with point-source BAT regulations will force

firms to close. The office uses econometric models to

study larger industries. These models deal with capital

requirements, pricing, future demand for products, and

the effects of regulation on industry growth.

3. Office of Water Program Operations (OWPO)—

Urban and agricultural runoff models are used to a limited degree by the national office of the Water Planning

Division of OWPO in planning studies. These models

are used at the State level to estimate potential runoff

and to evaluate different pollution control strategies, as

required under section 208 of the Clean Water Act.

4. OffIce of Water and Waste Management—EPA’s

Drinking Water Program in the Office of Water and

Waste Management has the responsibility to implement

provisions of the Safe Drinking Water Act, and it uses

some models to improve the decisionmaking process.

Under section 1412, for example, it uses health effects

models as part of the background information base for

setting standards and promulgating regulations. These

models provide data on the health risk from exposure

to contaminants in drinking water. Information from
184 . Use of Models for Water Resources Management, Planning, and Policy

such models has been used in the standard-setting process for radioactive and organic contaminants. The program also uses economic and benefit/cost models to

determine the economic effects of alternative policy and

regulatory options on the water supply industry.

Protection of underground sources of drinking water,

prescribed in section 1421 of the Safe Drinking Water

Act, is also a responsibility of the Drinking Water Program. Hazardous and toxic wastes have frequently been

disposed of through injection into underground formations. The program uses models to provide information

on the impact of injection practices on the natural system, the costs of constructing new wells, and the economic costs of shutting down existing wells. By comparing regulatory and remedial alternatives available, programs can be developed to balance the risks and costs

of contamination prevention measures.

The Drinking Water Program has also conducted a

major surface impoundment assessment authorized by

section 1442 of the act. The assessment includes a nationwide survey of surface impoundments in order to

determine their potential for contaminating ground

water. Uniform criteria were developed and used to

assess current and potential leakage of contaminants into

ground water. These criteria include, among others,

type of geology underlying the site, type of waste involved, proximity of aquifers, and capability of soil to

attenuate pollutants. Based on data collected, ground

water models can be developed to account for these factors in predicting an impoundment’s potential for contaminating ground water.

The Drinking Water Program also uses models to

evaluate State needs and capabilities in order to determine the appropriate grant amounts States receive

under section 1443 of the Safe Drinking Water Act.

These are financial models, but they take into consideration such factors as the number and type of injection

wells in the State, the number of wells used as part of

a water supply system, the geographic area, and the

manpower available in the State.

Models have also been used to develop a more complete understanding of sole-source aquifers. These

ground water resources may, in some parts of the country, provide the only available source of water. Models

provide information on the impact of discharges and

other economic activities on these sources of drinking

water. Facilities that may adversely affect these aquifers

include: leaking underground gasoline storage tanks,

waste disposal sites, improper land use, construction of

roads and buildings in the recharge zone, and pollution

of adjacent streams. Once the relative impacts of sources

of contamination are determined and evaluated, EPA

works with State agencies and communities to establish

and enforce procedures to prevent future aquifer contamination.

5. Office of Toxic Substances (OTS)—EPA’S OTS

uses models in several of the programs it carries out

under current water resource legislation. The principal

focus of its model use is the transport and fate of toxic

chemicals released into the aquatic environment. Currently, models are being used in OTS for risk assessment studies, to estimate the movement of pollutants

through the environment and their expected environmental concentrations. The office uses models in connection with activities under the Toxic Substances Control Act. Its models help measure the effectiveness of

regulatory options in order to set standards according

to sections 4, 5, and 6 of the act, which deal with testing, issuing manufacturing and processing notices, and

regulating hazardous chemical substances and mixtures.

OTS uses a three-step analysis to determine whether

a substance should be regulated, and, if so, how stringent the regulation should be—such regulation could

range from labeling a substance as hazardous to banning its use entirely. The office first determines the exposure of human and nonhuman populations to the toxic

substance. It then combines this exposure information

with estimates of health and ecological effects for various

exposures. Finally, the office weighs these costs against

the benefits of using the substance. Models are used in

accomplishing the first step of the analysis.

In addition to this use of models, OTS uses models

to help design chemical testing programs and to develop

monitoring studies carried out under provisions of the

Toxic Substances Control Act.

OTS is also involved in programs under the Federal

Insecticide, Fungicide, and Rodenticide Act of 1972

(Public Law 92-516), and uses models in conducting

these programs. In its review of pesticide product registrations, OTS must consider the potential effect of the

substance on ground and surface waters. In this connection, OTS uses models to assess pesticide runoff

potential and the likelihood of ground water contamination by pesticides, and to predict pesticide concentration in streams. OTS also uses models for advising State

and local agencies of the likelihood of ground water contamination by pesticides.

OTS mainly uses the EXAMS model, although its

Evaluation Division makes limited use of ARM-II in

pesticide screening studies. OTS is developing multimedia (water, air, land) models for preliminary assessments of a chemical’s behavior in the environment.

These models provide concentration estimates used in

the exposure calculations that support risk analysis. The

multimedia formulations are capable of accommodating

various types of chemicals and modes of release into the

environment. In addition, two ground water contamination models are being developed for OTS.

6. Office of Water Enforcement—EPA’s Office of

Water Enforcement uses models in connection with its
App. B—Summary of Model Use by Individual Federal Agencies ● 185

activities under the NPDES permit program and sections 301 and 316 of the Clean Water Act. The NPDES

program under section 402 of the Clean Water Act requires issuance of permits to regulate discharge of pollutants into the Nation’s waters. Permit limits are either

technology or water quality based. When technology-based limits are unavailable or inadequate to meet

water quality standards, permits are based on ‘‘best professional judgment, ’ which may include the use of

wasteload allocation or other water quality models. In

addition, water quality models, dispersion models, and

hydrological models are used to measure compliance

with water quality standards.

Under section 316 of the Clean Water Act, which

authorizes variances from thermal discharge standards,

the office uses predictive studies of entrainment and impingement losses to populations of fish and shellfish in

enforcing regulations governing powerplant siting. It

also uses fish population models and hydrological models

for the cooling intake structures program.

Section 301, which includes environmental and economic variances, demands the use of models when predictive demonstrations are needed to establish ambient

concentrations of nonconventional pollutants.

National Science Foundation (NSF)

NSF does not use water resource models, nor does

it directly fund the development of specific models. It

does, however, fund basic research at universities that

may contribute to the formulation of water resource

models. Such research may also produce components

and mathematical techniques that can be used in developing such models or in checking their scientific

validity.

The research NSF funds in the area of water resources

is for the purpose of building a firm scientific foundation, wherever possible, for empirical procedures and

practices that are used in developing water resource

models. Well-known examples are rainfall-runoff relationships and rainfall-soil erosion relationships.

NSF responds only to unsolicited basic research proposals in water resource engineering. During fiscal year

1979, NSF supported hydrologic and water resource

studies on hydrologic data, irrigation, planning, flood

forecasting, reservoir control, and surface runoff, among

others. Any or all of these topics may have models associated with the project.

Water Resources Council (WRC)

WRC encourages Federal, State, and local governments and private enterprise to conserve, develop, and

use water and related land resources on a comprehensive and coordinated basis. WRC also conducts periodic

national water assessments to identify the Nation’s critical water problems.

For its Second National Assessment in 1978, WRC

developed a water supply adequacy model. This model

is based on the concept of a balance between water use

and water supply for both ground and surface water.

The model is comprised of 21 water resource regions

and 106 subregions. The subregions have data on water

inflow or supply from upstream subregions, interbasin

imports, precipitation runoff, and ground water. Water

uses include interbasin exports, consumption, and

evaporation. Ground water recharge is accounted for

in the model and is not considered a loss. The hydrologic

and water-use data fed into this model were derived

through models incorporating precipitation records,

runoff estimates, economic growth projections, and

other measured or calculated variables at the wateraccounting-unit level (352 nationwide). These models

were produced or operated for WRC by various Federal,

State, and regional agencies.

The water supply adequacy model helped identify

several water supply problems. These included shortages

resulting from poor distribution of supplies, instream -

offstream conflicts, competition among various offstream users, ground water overdraft, quality degradation of ground and surface water, and institutional conflicts that prevent a unified approach to water management.

WRC’S Water and Energy Program was authorized

by the Federal Nonnuclear Energy Research and Development Act of 1974 (sec. 13 of Public Law 93-577),

which directs WRC to conduct regional and site-specific

water resource assessments of potential energy developments. For this purpose, a number of computerized

models have been used by various WRC contractors and

other Federal and State agencies, e.g. , the Colorado

River System Simulation (CRSS) of the Bureau of

Reclamation and the respective models of the White

River developed separately by Utah and Colorado.

These, and similar models, evaluate flow regime, hydropower impacts, salinity and suspended solids concentrations, and other water quantity and quality changes

anticipated from energy developments.

WRC presently evaluates river basin plans pursuant

to section 209 of the Clean Water Act. It is testing a

model that assesses water quality impacts of existing or

proposed river basin management schemes—specifically, in its Yadkin-Pee Dee Level-B study.

Some river basin commissions under the purview of

WRC use models to help plan or evaluate projects developed under section 102 of the Water Resources Planning Act. This section deals with regional or river basin

plans and programs and their relationship to other considerations. The commissions use models to analyze the

impacts of potential projects on water supply, to estimate depleted flows at key gaging stations, and to com-
186 . Use of Mode/s for water Resources Management, Planning, and Policy

pare the cost effectiveness of alternative wasteload reduction strategies.

Federal Emergency Management Agency

The Federal Emergency Management Agency,

through the Federal Insurance Administration (FIA),

administers the National Flood Insurance Program as

established by the National Flood Insurance Act of 1968

(Public Law 90-488). The program provides flood insurance availability to property owners within communities

that adopt and enforce minimum flood plain management measures to mitigate future flood losses. The act

also requires the identification of flood-prone areas and

risk zones within such areas.

Flood insurance studies are conducted for individual

communities to establish flood plains, floodways, regulatory flood elevations, and insurance risk zones. These

data are often developed using models and are subsequently provided to participating communities as the

basis for their flood plain management program. They

are also used to establish actuarial flood insurance rates.

Several different hydrologic models have been used

by FIA to establish flood flow frequencies and for flood

hydrography routing. The most commonly used hydrologic models are the HEC-1 Flood Hydrography Package, developed by the Corps of Engineers, and the

TR-20 Computer Program for Project Formulation, developed by SCS. These models simulate the rainfallrunoff process on watersheds and flood hydrography progression in downstream channels.

Several hydraulic models have been used to establish

flood elevations and floodways in streams. The most

commonly used hydraulic models are the HEC-2 Water

Surface Profile Package, developed by the Corps of Engineers, WSP-2 (TR61) and FLDWY (TR-64), developed by SCS, and E431, developed by USGS. These

models simulate open channel steady uniform flow using

the standard step backwater method.

FIA has also developed two coastal storm surge models, including one for northeasters and one for hurricanes. These models utilize joint probability techniques

and coastal hydrodynamic principles to establish regulatory flood elevations on the Atlantic and Gulf coasts of

the United States. A finite element model has also been

established to simulate storm surges in the Chesapeake

Bay.

Nuclear Regulatory Commission (NRC)

NRC water resource activities are related to determining hydrologic factors in nuclear facility site evaluations, ecological effects of water use, and radionuclide

transport in ground and surface waters. NRC has used

models in connection with all of these programs. For

example, to comply with regulations under section 102

of the National Environmental Protection Act, NRC

used models to evaluate powerplant intake effects on

Hudson River striped bass.

NRC has specific responsibilities under the Uranium

Mill Tailings Radiation Control Act and the Atomic Energy Act. Under the first act, NRC uses models to determine the movement and concentration of ground water

pollutants from uranium mill tailings. Information provided by these models was used to prepare a generic environmental impact statement on uranium milling and

associated rule changes. NRC also uses models to support various licensing actions. Models help support

licensing decisions for uranium mills, tailings disposal

systems, and uranium extraction operations. Models

also help measure compliance with regulations and license conditions.

Under the Atomic Energy Act, NRC uses models to

help it evaluate proposed sites for nuclear powerplants,

fuel cycle facilities, and waste disposal sites. Models are

used to help determine whether a plant’s water supply

is adequate for safety-related functions, as specified in

regulations. NRC also uses models to evaluate whether

proposed nuclear facilities are in compliance with regulations governing flood protection.

Models have been used by NRC in carrying out its

responsibilities under the Atomic Energy Act to limit

radioactive liquid effluents to ground and surface waters.

NRC is using models to help prepare an EIS and to formulate proposed regulations governing the disposal of

low-level radioactive waste and low-activity bulk solid

waste. The models are presently being used to evaluate

siting criteria and alternative disposal techniques in

terms of radionuclide transport and concentrations at

site boundaries. When disposal site regulations are

adopted, site-specific models will be used to determine

whether adequate protection exists to prevent radionuclide migration from exceeding acceptable limits.

Models are also used to help determine whether other

types of nuclear facilities are in compliance. These models help evaluate potential concentrations of radionuclides in ground and surface waters as a result of both

accidental and normal releases.

NRC provides assistance to States in the use of models

to evaluate radionuclide migration from disposal sites.

This is done as part of the agreement State program,

through which certain States, pursuant to section 274

of the Atomic Energy Act, have entered into an agreement with NRC for assuming regulatory control of byproduct, source, and small quantities of special nuclear

materials.
App. B—Summary of Model Use by Individual Federal Agencies . 187

ATTACHMENT I.—REFERENCES BY AGENCY

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Economics and Statistics Service

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Modeling System, LA WREMS Directoxy, version

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‘‘LAWREMS, Land and Water Resources and

Economic Modeling System, Current Capabilities,

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1979.

Forest Service

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Agricultural Management Systems, Science and

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537, 1978.

Soil Conservation Service

9. Ecology Simulations, Inc. , Athens, Ga. ,

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for Assessment, Evaluation and Optimization of

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Projects, With Application to Horse Range

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1979.

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mimeograph, 1979.

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for Hydrologic Forecasting in the National

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E. L., “National Weather Service Extended

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App. B—Summary of Model Use by Individual Federal Agencies 189

Department of Energy

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of Data Bases, Graphics Packages, and Models in

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Jackman, Alan P. and Yotshkura, Nobuhiro,

“Thermal Loading of Natural Streams, ” U.S.

Geological Survey professional paper 991, 1977.

Jennings, Marshall E. and Yotshkura, Nobuhiro,

“Status of Surface-Water Modeling in the U.S.

Geological Survey, ’ Geological Survey circular

No. 809, 1979.

Konikow, Leonard F., “Modeling Chloride

Movement in the Alluvial Aquifer at the Rocky

Mountain Arsenal, Colorado, ” U.S. Geological

Survey water supply paper 2044, 1977.

Konikow, L. F. and Bredehoeft, J. D., “Computer Model of Two-Dimensional Solute Transport and Dispersion in Ground Water, USGS

book 7, ch. 2, 1978.
190 ● Use of Models for Water Resources Management, Planning, and Policy

68.

69.

70.

71.

72.

73,

74.

75.

76

77.

Konikow, Leonard F., and Bredehoeft, John D.,

“Modeling Flow and Chemical Quality Changes

in an Irrigated Stream-Aquifer System, Water

Resources Research, vol. 10, No. 3, June 1974.

Laird, L. B., “Response to OTA Questionnaire:

Task Force on Water Resource Modeling in the

Federal Agencies, ” personal correspondence,

October 1979.

Larson, Steve, personal interview, August 1979.

McKenzie, Stuart W., et al., “Steady-State Dissolved Oxygen Model of the Willamette River,

Oregon, ” U.S. Geological Survey circular 715-J,

1979.

Plummer, L. Niel, et al., ‘‘ WATEQF-A

FORTRAN IV Version of WATER, A Computer

Program for Calculating Chemical Equilibrium of

Natural Waters, ” USGS, Water Resources Investigations 76-13, September 1976.

Trescott, Peter C., ‘‘Documentation of Finite-Difference Model for Simulation of Three-Dimensional Ground-Water Flow, ” U.S. Geological Survey

report 75-438, September 1975.

Rickert, David A., and Hines, Walter G., “River

Quality Assessment: Implications of a Prototype

Project, ’ Science, vol. 200, pp. 1113-1118, June

1978.

Trescott, Peter C., ‘‘Documentation of Finite-Difference Model for Simulation of Three-Dimensional Ground-Water Flow, U.S. Geological Survey

report 75-438, September 1975.

Trescott, P. C., Pinder, G. F., and Larson, S. P.,

‘‘Finite-Difference Model for Aquifer Simulation

in Two Dimensions with Results of Numerical Expediments, ” ch. 1, book 7 of Techniques of

Water-Resources Investigations of the U.S. Geological Survey.

U.S. Geological Survey, “Computer Programs for

Modeling Flow and Water Quality of Surface

Water Systems, ” September 1978.

Bureau of Reclamation

78.

79.

Bureau of Reclamation, ‘‘Response to OTA Questionnaire: Task Force on Water Resource Modeling, ” personal communication, November 1979.

Bureau of Reclamation, “Response to OTA Questionnaire: Task Force on Water Resource Modeling in Federal Agencies, personal correspondence, October 1979; Bureau of Reclamation, Bureau of Reclamation Economic Assessment Model

(BREAM) Technical Description, January 1978;

Ribbens, Richard W., Technical Description of

Return Flow Quality Simulation Model, Water

and Power Resources Service, January 1980.

Independent Agencies

Council on Environmental Quality

80

81

82

Buffington, J. D., Milask, L. J., “An Overview

of the UPGRADE Data Analysis System.

CEQ Executive Summary, response for OTA

Water Resources Workshop.

C E ~ “ ‘Strawman’ Responses to Objectives of

the OTA Task Force on Water Resourses Modeling, “ Oct. 24-25, 1979.

EPA: Office of Research and Development

83.

84.

Office of Research and Development, “Response

to OTA Questionnaire: Task Force on Water Resource Modeling in Federal Agencies, personal

correspondence, October 1979.

Richardson, W. L., and Thomas. N. A.. “A

Review of EPA’s Great Lakes Modeling ‘Program, ‘‘ in Proceedings of the EPA Conference on

Environmental Modeling and Simulation, W. R.

Ott (cd.), report No., EPA-600/9-76-106 (Cincinnati, Ohio: Environmental Protection Agency,

1976).

EPA: Office of Toxic Substances

85.

86<

87.

Wood, B., “Response to OTA Questionnaire:

Task Force on Water Resource Modeling in Federal Agencies, personal correspondence, October

1979.

Survey and Analysis Division, Office of Toxic Substances, “Response to OTA Questionnaire: Task

Force on Water Resource Modeling in Federal

Agencies, personal correspondence, October

1979.

Zweig, G., “Response to OTA Questionnaire:

Task Force on Water Resource Modeling in Federal Agencies, personal correspondence, October

1979.

EPA: Office of Water Planning and Standards

88.

89.

90.

Athway, D., and Somers, P., staff, Urban Runoff

Program, Implementation Branch, Water Planning Division, Office of Water Planning and

Standards, EPA, personal interview, Aug. 17,

1979.

Cogger, B., “Response to OTA Questionnaire:

Task Force on Water Resource Modeling in Federal Agencies, personal correspondence, October

1979.

Dupuis, L., staff, Office of Analysis and Evaluation, Water Planning and Standards, EPA, personal interview, Aug. 17, 1979.
App. B—Summary of Model Use by Individual Federal Agencies . 191

91.

92.

93

94.

95.

96

Ehreth, D., Callahan, M., Frederick, R., and

Slimak, M., staff, Water Quality Analysis Branch,

Monitoring and Data Support Division, Office of

Water Planning and Standards, EPA, personal interview, Aug. 17, 1979.

Myers, C., staff, Implementation Branch, Water

Planning Division, Office of Water Planning and

Standards, EPA, personal interview, Aug. 17,

1979.

Office of Analysis and Evaluation, “Response to

OTA Questionnaire: Task Force on Water Resource Modeling in Federal Agencies, personal

correspondence, October 1979.

Stuart, T., Chief, Monitoring Branch, Office of

Water Planning and Standards, EPA, personal interview, Aug. 17, 1979.

Swader, F., staff, Agricultural Runoff Program,

Implementation Branch, Water Planning Division,

Office of Water Planning and Standards, EPA,

personal interview, Aug. 22, 1979.

Water Quality Analysis Branch, “Response to

OTA Qestionnaire:” Task Force on Water Resource Modeling in Federal Agencies, personal

correspondence, October 1979.

EPA: General References

97.

98<

99.

100.

101.

Beckers, C. V., Parker, P. E., Marshall, R. N.,

and Chamberlain, S. G., ‘‘ RECEIV-11, A Generalized Dynamic Planning Model for Water Quality

Management, in Proceedings of the EPA Conference on Environmental Modeling and Simulation,

W. R. Ott (cd.), report No. EPA-600/9-76-100

(Cincinnati, Ohio: Environmental Protection

Agency, 1976).

Environmental Protection Agency, ‘‘A Statistical

Method for the Assessment of Urban Stormwater, report No. EPA 440/3-79-023, prepared

for Environmental Protection Agency, Washington, D. C., May 1979.

Falco, J. W., and Mulkey, L. A., “Modeling the

Effect of Pesticide Loading on Riverine Ecosystems, ‘‘ in Proceeding-s of the EPA Conference on

Environmental Modeling and Simulation, W. R.

Ott (cd.), report No. EPA-600/9-76- 106 (Cincinnati, Ohio: Environmental Protection Agency,

1976).

Leytharn, K. M., and Johnson, R. C., “Watershed Erosion and Sediment Transport Model,

Report No. EPA-600/3-79-028, prepared for Environmental Protection Agency, Athens, Ga. ,

March 1979.

Pechan, E. H., and Luken, R. A., “Watershed

Erosion and Sediment Transport Model, ’ report

102.

103

104

No. EPA-600/3-79-028, prepared for Environmental Protection Agency, Athens, Ga., March 1976.

Taylor, P. L., “STORET: A Data Base for

Models, ‘‘ in Workshop on Verification of Water

Quality Models, report No. EPA-600/9-80-016,

prepared for Environmental Protection Agency,

Athens, Ga., April 1980.

True, H. A., ‘ ‘Planning Models for Non-Point

Runoff Assessment, in Proceedings of the EPA

Conference on Environmental Modeling and Simulation, W. R. Ott, (cd.), report No. EPA-600/

9-76-106 (Cincinnati, Ohio: Environmental Protection Agency, 1976).

Versar, Inc., ‘‘ Environmental Assessment of Priority Pollutants: A Review of Evaluative Models

in Assessing the Fate of Pollutants, Final Report,

contract No. 68-01-3852, prepared for Environmental Protection Agency, Washington, D.C.

February 1979.

National Science Foundation

105. Ezra, A. A., “Executive Summary and ‘Strawman’ Responses to Objectives of the OTA Task

Force on Water Resource Modeling, ’ Oct. 24-25,

1979.

Water Resources Council

106. Walker, Lewis D., Water Supply Adequacy Analysis Model, for the OTA Task Force on Water Resource Modeling in the Federal Agencies, Oct.

24-25, 1979.

General References

107.

108.

109

110,

111,

Brandstetter, A. G., ‘ ‘Assessment of Mathematical

Models for Storm and Combined Sewer Management, report No. EPA-600/2-76- 175a, prepared

for Environmental Protection Agency, Cincinnati,

Ohio, August 1976.

Bugliarello, G., and Gunther, F. C., Developments in Water Science I: Computer Systems

and Water Resources (New York: Elsevier Publishing Co., 1974).

Chung, Sang Chu, et al., Computer programs in

Water Resources, Minnesota University Water

Resources Research Center, November 1977.

Grimsrud, G, Paul, et al., Evaluation of Water

Quality Models: A Management Guide for Planners (Palo Alto, Ca]if.: Systems Control Inc.,

1976).

Hinson, M. O., and Basta, D. J., “Analyzing Receiving Water Systems, ‘‘ in Analysis for Residuals
192 ● Use of Models for Water Resources Management, Planning, and Policy

112

113

—Environmental Quality Management: Analyzing Natural Systems, Resources for the Future,

D. J. Basta and B. T. Bower (eds. ), Washington,

D. C,, prepared for the Office of Research and De- 114.

velopment, Environmental Protection Agency,

December 1979.

Horton, M. L., et al., Analysis and Dissemination 115.

of Water Resources Information, South Dakota

State University Water Resources Institute, 1979.

Huber, W. C., and Heaney, J. P., “Analyzing

Residuals Generation and Discharges From Urban

and Nonurban Land Surfaces, in Analysis for 116,

Residuals-Environmental Quality Management:

Analyzing Natural Systems, Resources for the

Future. D. 1. Basta and B. T. Bower (eds.\. Washington, D. C., prepared for the Office of Research

and Development, U.S. Environmental Protection

Agency, December 1979.

Marks, David H., “Models in Water Resources,

in A Guide to Models in Governmental Planning

and Operations, EPA, August 1974.

U.S. Environmental Protection Agency, Environmental Modeling and Simulation, Washington,

D. C., Office of Research and Development and

Office of Planning and Management, EPA-600/

9-76-016, 1976.

Viessman, W., Jr., Knapp, J. W., Lewis, G. L.,

and Harbaugh, T. E., Introduction to Hydrology,

2d ed. (New York: Harper & Row, 1977).

, “ \ / >
App. B—Summary of Model Use by Individual Federal Agencies 193

ATTACHMENT II. —SURVEY OF FEDERAL AGENCY

MODEL USE RELATED TO MAJOR LEGISLATION

July 14, 198 0

CONGRESS OF THE UNITED STATES

Office of Technology Assessment

Washington, D C 20510

1 .

7. .

3 .
194 . Use of Models for Water Resources Management, Planning, and policy

?. . ——————.—— pro~rarn T f t 1 e and l,e~ is la t ive —.—Autbor ~ za t ion ——

Fi 11 in the proqram t i tle a t the top of eacb quest i onna ire .

Provide the author i za t ion i f i t is not on the “a ter ?ro~ram

Checklist or otber than authorization 1 istecl .

3. —- r~~plete the O~]est —.—>.—_—.—.-–?.- i onna ire (s)

A part ia 1 example quest ionna ire is c iven bel ow:

LeCi slat i ve Author 5 za t i on - Puhl ic law Q5-? 17

T’elevant qec t ion of

Specific Purpos e Law, Rule, Renul a t ion T<ane o f ‘!o Ae 1 (s ~

Act i vitv lfode 1s are Used -or ARency C(I i de 1 i nr ——- .or Cener ic Tvpe —.————. . .——. . ——.— J——.

En fore e Power Plan t Sect i on 316 t enp. mode 1s

~e~u- S i t infi 1!SP and l!n ECW

lat ions,

St an[la rcls,

Cu ide 1 ines

4 . ——————— .4c!cI i t i ona 1 Comments - Any add i t i o na 1 c omnc n ts may be wr i t t e n o n

the hack of the Tncl i vidual Pro~ram (?uest i onna i res.

If yotl have any quest ions ahout the survey, pl ease do not hesi tatc t o

cal 1 Robert Friedman, Project Director, a t ( 2n? ) 2?4-7031 .

?1 ease ma i 1 the compl e ted !.!a ter Vropram Checkl i st and Intlividual

l’roflram Questionnaire(s) to :

-—

IX. Rot~ert ~~. Frje~man

Project Director

Office of TechnoloFv Assessmen t

U.S. ConRress

IIashinpton, ~.C. ?(-151~
—

App. B—Summary of Model Use by lndividual Federal Agencies ● 195

PART I : WATER PROGRAM CHECKLIST

- .

Co I umn

One

Program

Involve -

ment

[ 1

[ 1

[ 1

[ 1

[ 1

[ 1

[ 1

L]

[1

[ 1

[ 1

[ 1

[ 1

[ 1

[ 1

[ 1

[ 1

Lo 1 umn

Two

Model

Use

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

FEDERAL WATER POLLUTION CONTROL ACT AMENDMENTS OF 1972

(AS AMENDED BY THE CLEAN WATER ACT OF 1977)

Grants for pollution control programs

Mine water pollution control programs

Grants for construction of treatment works

Areawide waste treatment management

Basin planning

Water quality related effluent limitations

Water quality standards and implementation plans

Toxic and pretreatment effluent standards

Oil and hazardous substances liability

Clean lakes

Thermal discharges and exemptions

Guidelines. . . permits for dredged or fill material

Disposal of sewage sludge

SAFE DRINKING WATER ACT

Protection of underground sources of drinking water

Special study and demonstration project grants for waste

water reuse, reclamation and recycling processes

TOXIC SUBSTANCES CONTROL ACT

Testing of chemical substances and mixtures

Regulation of hazardous chemicals and mixtures

Section

S. 106

s. 107

s. 201

S. 208

S. 209

S. 302

s. 303

s. 307

s. 311

s. 314

S. 316

s. 404

s. 405

S. 1421

s. 1444

s. 4

S. 6
196 ● use of Mode/s for water Resources Management, planning, and Policy

Column Column

One Two

Program

Involve- Model

ment Use

[1 [1

[1 [1

[1 [1

[1 [1

[1 [1

[1 [1

[1 [1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

[1

RESOURCE CONSERVATION AND RECOVERY ACT

Solid waste management guidelines

Identification and listing of hazardous wastes

Standards for owners and operators of hazardous

treatment, storage and disposal facilitie s

Page 2

Section

S. 1008

s. 3001

waste

Consolidated permits for hazardous waste management

facilities

Grants for state resource recovery and conservation

Full scale demonstration facilities grants

Resource recovery systems and improved solid waste

disposal facilities

ENDANGERED SPECIES ACT

Minimizations of impacts of Federal activities

modifying critical habitats

SURFACE MINING CONTROL AND RECLAMATION ACT

Surface coal mine reclamation permitting

Environmental protection performance standards for

surface coal mine reclamation

SOIL AND WATER RESOURCE CONSERVATION ACT OF 1977

Data collection about soil, water and related

resources

Soil and water conservation programs

WATER RESOURCES PLANNING ACT

s. 3004

s. 3005

plans S. 4008

S. 8004

s. 8006

s. 7

S. 506

s. 515

s. 5

S. 6

Regional or river basin plans and programs and their

relation to larger region requirements s. 102

Coordinating Federal water and related land resources

programs and policies s. 102
App. B—Summary of Model Use by Individual Federal Agencies ● 197

Page 3

Column Column

One Two

Program

Involve- Model

ment Use Section

COASTAL ZONE MANAGEMENT ACT

[1 [1 State coastal zone land and water resources management

program development and management grants s. 305

EXECUTIVE ORDER 11988

[1 [1 Floodplain management S. 2&3

FLOOD CONTROL ACT OF 1936 AND AMENDMENTS

[1 [ 1 Flood control structures S. 1,2,3

WATER RESOURCES DEVELOPMENT ACT OF 1974

[1 [ 1 Nonstructural measures s. 73

FEDERAL RECLAMATION ACT OF 1902 AND AMENDMENTS

Irrigation distribution systems

Construction of small projects

[1

[1

[ 1

[1

(43 U.S.C. 421)

(43 U.S.C. 422)

OTHER ACT

[1 Other Programs

[ 1

[1

[1 s.

s.

s.

[1

[1

OTHER ACT

[1

[1

[1

[1

[1

[1

Other Programs s.

s.

s.
198 . Use of Models for Water Resources Management, Planning, and Policy

PART I I : INDIVIDUAL PROGRAM QUESTIONNAIRE

PROGRAH Respondent

(fill inonly one program on each Questionnaire)

— ——— —

OffIce

Legislative authorization Agency

(If not on OTA program list or other than

——— — —

authfi~zation listed on Water Program Checklist) Phone Number

●

Relevant Section of Law,

Actlvlties Specific Purposes for which Models are Used Rule, Regulation or Name of Model(s

Agency Guideline or Generic Type

—

Program Planning

and Scope

Promulgate Regulations,

Set Standards, Oevelop

Guidelines

Enforce Regulations,

Standards, Guidelines

Comply with Regulations,

Standards, Guidelines

Plan or Evaluate

Projects, Activities

Allocate Plannlng or

ConstructIon Funds

State or Local

Advisory Assistance

Operation and Management

Other Program Activities

.
.

Appendix C

Summaries of Related Modeling Studies

This appendix summarizes five previously completed

studies of model development, use, and dissemination—

three conducted wholly within the United States, one

from Canada, and one international assessment. The

five were chosen for their currency and relevance to the

issues raised in this report, and largely corroborate OTA

findings regarding current modeling issues. They are:

1.

2.

3.

4.

5.

“Federally-Supported Mathematical Models: Survey and Analysis, National Science Foundation

(NSF), 1974.

“Ways to Improve Management of FederallyFunded Computerized Models, ” General Accounting Office (GAO), 1976.

‘‘A Study for Assessing Ways to Improve the Utility of Large-Scale Models, ’ National Bureau of

Standards (NBS), 1978.

“Survey of Environmental Management Simulation Models in Canada, ’ R. D. Miller.

“SCOPE International Assessment Project on

Groundwater Model Modeling”

1. “Federally-Supported Mathematical

Models: Survey and Analysis” (Fromm,

Hamilton, & Hamilton)

This survey was completed in 1974 by NSF. It surveyed a universe of over 650 models which addressed

some aspect of social decisionmaking, and which were

used by or developed for nondefense Federal agencies.

Responses were received for 222 models, from over 230

project directors and 80 Federal agency monitors.

Respondents indicated that the most important constraints limiting model utility were: 1 ) data availability, and 2) ease of use by nontechnicians. Responses also

indicated a prevailing tendency for actual use of models

to fall short of intended use. Policy-related model uses

appeared to have the greatest shortfall—between onethird and two-thirds of the models failed to achieve their

stated purposes with respect to direct application to policy problems.

Based on survey responses, staff attributed low policy

utilization rates for models primarily to lack of communication between model builders and potential policymakers during model development, and secondarily to

policy makers’ limited capabilities to use models once

they had been developed. The study found very little

interaction between developers and users during model

development— actual briefings were held in only 19 percent of the projects, and user agencies ran models and

analyzed results in only 34 percent; written reports alone

were provided in over 50 percent of surveyed modeling

projects. Most of the projects were supported by grants,

with very infrequent specification of performance requirements or desired detail and characteristics by the

funding agency.

The survey identified two dimensions to the “ease

of use” problem: 1) decisionmaker understanding of

models, and 2) the adequacy of developer-supplied instructions for operating the model. Both developers and

agency personnel noted that policy makers frequently

lack the training that would equip them to use models

appropriately. On the other hand, in about 75 percent

of the surveyed cases, the documentation supplied by

the developer was considered inadequate to enable nonproject personnel to set up and run the model. The majority of the documentation efforts failed to include user

manuals, operating instructions, or computer programs.

Use rates were found to be highest for models having

user manuals; these tended to be produced when funding agencies specified desired model characteristics, and

when funding was carried out under contracts rather

than grants.

2. “Ways to Improve Management of

Federally-Funded Computerized Models”

This 1976 survey conducted by GAO was based on

responses to questionnaires regarding 519 federally

funded models developed and/or used in the U.S. Pacific

Northwest. Fifty-seven of those models costing over

$100,000 to develop were selected for detailed review—

and 33 of these were described by respondents as having encountered ‘‘major problems’ in development.

GAO characterized these problems as being due to:

. inadequate management planning (70 percent);

. inadequate management commitment (15 percent);

and

● inadequate management coordination (15 percent).

GAO found that model development problems tended

to result in models not being used once they are developed, cost overruns for models, and prolonged development time, The reasons most frequently given for model

development problems were: 1) the unreliability of model results, 2) developers’ inability to obtain necessary

data, and 3) users’ failure to allocate enough funds to

complete the model. GAO further outlined development

problems stemming from deficiencies in management

planning, commitment, and coordination:

● Problems attributable to inadequate management

planning:

199
200 Use of Models for Water Resources Management, Planning, and Policy

— Management did not clearly define the problem

to be modeled; thus, the developer had to guess

what had to be modeled.

— The developer was not able to obtain the data

needed to make the model function.

— Management allocated insufficient funds to

complete the model.

— Management did not make workable provisions

for updating the model for future use; thus, the

model soon began to produce outdated information.

— Management did not make provisions for evaluating the model.

— Management did not clarify documentation requirements for the model. As a result, only the

developer understood how it worked and the relationship maintained by the variables incorporated into it.

● Problems attributable to inadequate management

commitment:

— Management did not actively participate in

planning of the model. Thus, the model did not

clearly reflect their needs.

— Management did not understand computer

modeling techniques and applications. Consequently, they could not effectively use information obtained from the models.

● Problems attributable to inadequate management

coordination:

— Management did not monitor the model development effort on a cent continuous basis. Thus,

management allowed development efforts to

continue after they should have been terminated.

— Managers did not coordinate the development

effort with the developer. As a result, the model

was developed without reasonable assurance

that it would meet user needs.

Two major solutions for these problems were proposed in the GAO report: First, the use of a phased approach to model development, requiring the funding

agency to review projects and decide whether to continue development at the end of each of five stages:

1) problem definition, 2) preliminary design, 3) detail

design, 4) evaluation, and 5) maintenance. This suggested procedure is seen as promoting a more thorough

early investigation of the nature of the problem and of

possible solution methods, as well as providing a method

of controlling commitments to modeling efforts.

GAO’s second proposal was that the Department of

Commerce and the General Services Administration,

using their respective authorities under the Brooks Act

(Public Law 89-306), formulate Government-wide

standards and guidance on developing and procuring

computerized models, and coordinate with other Federal

agencies to obtain advice regarding such standards and

guidance.

3. “A Study for Assessing Ways to Improve

the Utility of Large-Scale Models”

(S. I. Gass, Z. F. Landsdowne,

R. P. Harvey, and A. J. Lemonine)

This study, completed in December 1978 for NBS,

surveyed a group of modelers selected for their recognized expertise and their interest in the modeling profession. Of 57 modelers who were requested to participate, 39 responded, yielding the following cross-section

of affiliations and expertise:

Affiliation Expertise

University 8 Analytic . . . . . . . . . .......19

Not-for-profi[ . . . . . . 8 Simulation . . . . . . . .. ....12

Profit . . . . . 9 Economics . . . . . 9

Government . . . . . . .*

Total ... . . .......3 9 Total . . . . . . . . . . . . . ~

These participants, responding to propositions and

statements in 18 model improvement area categories,

gave highest priority to proposals to clarify the relationship between model developer and user, and increase

the interaction between them. Strongest support was

voiced for such specific proposals as:

1.

2.

3.

4

5.

Model developers should specify a documentation plan in their contract, detailing the documents

to be produced, the resources allocated, and personnel responsibilities.

The Federal Government should establish a flexible set of model documentation guidelines that can

be used by model developers and sponsors to create

a project’s documentation plan.

Requests for proposals (RFPs) should indicate the

ultimate user of the model, and require meetings

between model developers and users to aid in designing models to meet user requirements.

Model developers should be required to prepare

verification and validation test plans, report results

of the tests, and describe their implications for future use of their models.

Model forums should be established by professional organizations, industrial groups, and-the Federal Government.

Participants also indicated strong support for coordinated model development and data collection. They supported mandatory data availability and costing assessments prior to the issuance of an RFP for a model, and

requirements for parallel data collection efforts to be

specified in the ‘ ‘scope of work‘‘ if necessary data are

not already available.

Moderate support was also expressed for: 1) requiring greater specificity in the RFP statement of work,
App. C—Summaries of Related Modeling Studies ● 201

including explicit statements of model scope and objectives; 2) Federal exploration of phased management approaches to model development; and 3) requiring all

model development contracts to address the issue of user

training.

Participants strongly disapproved of centralized Government-sponsored review and analysis relating to models, specifically rejecting model clearinghouses; a model

testing, verification, and validation center; and a Government modeling research center.

4. “Survey of Environmental Management

Simulation Models in Canada”

(R. D. Miller)

Simulation modelers in Canada who were involved

with developing environmental management models

were requested to complete questionnaires regarding the

models they had developed. Questions were directed toward

1.

2.

3.

4.

5.

five general areas:

purpose of the model, including the audience to

which it was directed;

degree of success, including implementation of the

model and its use in decisionmaking;

problems encountered during model development

and implementation;

planning and managerial factors that might serve

as predictors of success; and

technical details of how the simulation was carried out.

The overall results of the survey suggest that the surveyed model development projects suffered from lack

of involvement and meaningful contribution by decisionmakers in the early stages of model development.

A lack of user credibility accorded to the model was reported only in cases where users had not been involved

in managing the project. In these cases, user credibility was cited as a problem with far greater frequency

than the modeler’s willingness to help, suggesting that

modelers neglect to involve decisionmakers more often

than decisionmakers refuse to consider the advantages

of developing models.

Specific correlations were found between:

perceived success and attempts to involve users at

early stages of development, specifically by giving

system managers some voice in managing the simulation project;

perceived success and preproject literature searches

or state-of-the-art surveys;

perceived success and intended audience. Cases

where model output was to be used by technical

or research staff had a significantly better success

level than cases where model results were to be used

by policy formulation groups, or middle- or highlevel management; and

● model purpose and difficulties encountered during

the project. Where models were constructed primarily for research purposes, lack of understanding

of mechanisms, and lack of available data, were

most often cited as problems; where models were

intended for policy recommendations, lack of user

credibility was the most frequently named problem.

5. “SCOPE International Assessment Project

on Groundwater Model Modeling’

The SCOPE project was carried out between 1975

and 1977, primarily through surveys of two groups:

1) active model developers, and 2) those active in

applying models to management problems. Reports on

approximately 250 models were submitted in response

to the project survey.

The purpose of the assessment was to provide guidance on measures for improving the utility of models

in ground water management. Four major problem

areas were identified during the course of the project,

and were ranked by project staff and an international

steering committee in the following order of importance:

1. accessibility of models to users;

2. communications between managers and technical

personnel;

3. inadequacies of data; and

4. inadequacies of modeling.

The survey found difficulties in gaining access to existing models to be the most serious impediment to effective use of models in ground water management. Major

problems of accessibility revolve around the usability

of model documentation, model distribution, adequate

training in the use of models, and user certification.

Project staff suggested that improvements in these areas

would require shifts in the incentive structures of institutions, or even modifications to the institutions themselves. Their primary recommendation involved establishing public agency requirements for adequate documentation as a prerequisite for funding any model development effort.

To improve communication between managers and

technical personnel, the study staff recommended measures to increase interactive participation in problem definition and model application, so that managers become

directly involved in developing the models they commission. Additional recommendations included designing

model outputs to be easily understandable by nontechnical personnel, and encouraging further development of

management “decisionmaking” models.

Data-gathering recommendations stressed improved

methods for routine data collection, storage, and retrieval, and sensitivity analysis as a method of determining

the most critical data needs for modeling purposes.

. .- I .r{ - 11,
Appendix D

Additional References to Models

and Modeling Studies

Surface Water Flow and

Supply References

Table of Model Types (with

reference numbers)

General (50, 54, 66, 75, 82, 86, 112)

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

202

Watershed Soil/Water Process Models (5, 7, 9, 16,

18, 19, 23, 40, 41, 43, 53, 57, 59, 61, 88, 91, 95,

97, 98, 104, 108, 116, 117, 118, 119)

Snow Accumulation and Melt Models (1, 2, 3, 9,

16, 23, 40, 41, 43, 53, 59, 61, 98, 106, 118, 119)

Baseflow Models (5, 7, 9, 16, 19, 23, 34, 40, 41,

43, 52, 53, 57, 59, 61, 88, 98, 117, 118, 119)

Channel Routing Models (5, 9, 16, 18, 19, 28, 40,

41, 43, 47, 74, 91, 95, 97, 98, 104, 108, 119)

Lake and Reservoir Routing Models (19, 43, 47,

57, 97, 98)

Flood Formulae (24, 32, 37, 39,62, 73,80,93, 108)

Regional Flood Equations (24, 26, 48, 62, 64, 73,

87, 92, 115)

Regional Flood Simulation Models (24, 45, 62, 65,

125)

Flow Frequency Models (73, 78, 85)

Evapotranspiration Models (5, 9, 16, 18, 19, 23,

31, 40, 41, 43, 53, 57, 58, 59, 60, 61, 76, 77, 83,

91, 96, 97, 98, 107, 116, 117, 118, 119)

Unit Hydrography Models (22, 24, 39, 62, 94, 108)

Dam Failure Models (5, 10, 44)

Reservoir Water Accounting Models (9, 57, 98)

Annual Data Generation Models (27, 67,68,69, 79)

Regional Data Generation Models (20, 26, 36, 51,

64, 70, 79, 87, 111)

Reservoir Sedimentation Models (8, 15, 57, 98)

Ice Formation and Breakup Models (21, 25, 33, 71,

72, 81, 89, 102, 103, 120)

Freezing and Breakup Formulae (12, 21, 25, 33, 72,

81, 89, 102, 103, 120)

Plot Size Soil/Water Process Models (29, 31, 53,

57, 58, 59, 60, 61, 88, 95, 96, 108)

Plot Snow Accumulation and Melt Models (31, 53,

59, 60, 61, 96)

Bank Sloughing Models (109)

Flood Inundation Models (46)

Channel Erosion and Deposition Models (4, 84, 90,

101, 105)

Channel Geometry Equations (63, 99)

25. Irrigation Water Demand Models (57, 100)

26. Land Drainage Models (49, 57, 110, 114)

27

28.

29.

30<

31,

32,

1.

2.

3

4.

5.

6.

7.

8.

9.

(

1

1

Conduit Capacity Models ( 11)

Pipe Network Models (56, 113)

Regional Water Use Relationships (30, 42)

Annual Use Generation Models (17)

Plant Water Use Models (6, 13, 14, 35, 38, 55, 76,

77, 83, 107)

System Water Need Models (56)

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Surface Water Quality Model References

The following tables and figures are from:

D. J. Basta and B. T. Bower (eds. ), Analysis for

Regional Residuals— Environmental Quality

Management: AnaJyzing Natural Systems,

Resources for the Future Research Paper

(Baltimore, Md.: Johns Hopkins University Press

for Resources for the Future, 1982).

Figure D-1 displays 14 of the most widely used surface water runoff models, and the types of problems each

model is capable of analyzing. The following table (table

D-1) lists and identifies the originator of over 40 surface water runoff models, including the 14 from figure

D-1. Table D-1 is organized by the following categories:

screening procedures, simplified computer models, continuous simulation models, and single event simulation

models. The table includes those models that have

received most extensive use (both private and governmental models) and less widely used models developed

by governmental agencies.

Figure D-2 displays 27 of the most widely used receiving water quality models and the types of water bodies

and problems they address. Again, table D-2 follows

with a more extensive list of models, concentrating on

those most widely used and/or developed by a Government agency.
App. D—Additional References to Models and Modeling Studies . 207

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208 . Use of Models for Water Resources Management, Planning, and Policy

TABLE D-1

Commonly Used Surface Water Runoff Models

Model Name Commonly Used Acronym Originator

SCREENING PROCEDURES

Hydroscience Simplified Model

Storm Water Management Model,

Level I

Midwest Research Institute

Loading Functions

SIMPLIFIED COMPUTER

Rational Method

Los Angeles Hydrography Method

Santa Barbara Urban Hydrography

Method

--- Hydroscience, Inc.,

Westwood, N.J.

SWMM-Level I Dept. of Environmental

Engineering Science,

University of Florida,

Gainesville, Florida

MM

-—

---

SBUH

Environmental Pollution Assessment- EPARRB

Erosion, Sedimentation and Rural

Runoff Model

TVA Stormwater Model

Midwest Research Institute,

Kansas City, Missouri

---

City of Los Angeles,

Los Angeles, California

Santa Barbara County Flood

Control and Water

Conservation District,

Santa Barbara, California

National Environmental Research

Center, Environmental

ProtectIon Agency, Athens,

Georgia

Division of Water Control

Planning, Tennessee Valley

Authority, Knoxville,

Tennessee

Simplified Storm Water Managemnt Simplified SWMM Metcalf and Eddy, Inc.,

Model Palo Alto, California

CONTINUOUS SIMULATION

Stanford Watershed Model Variants

Stanford Watershed Model IV SUM-IV Department of Civil Engineering,

Stanford University, Palo

Alto, California
App. D—Additional References to Models and Modeling Studies ● 209

TABLE D-1 (Continued)

Commnlv Used Surface Water Runoff Models

Model Name Commonly Used Acronym Originator

Kentucky Watershed Model KWM University of Kentucky,

Lexington, Kentucky

Self-Optimizing, Continuous OPSET University of Kentucky,

Hydrologic Simulation Model Lexington, Kentucky

National Weather Service River NWSRFS Office of Hydrology, National

Forecast System Weather Service, Silver

Spring, Maryland

Sacramento Model

TVA Daily Flow Model

Hydrocomp Simulation Program

Pesticide Transport and Runoff

Model

Agricultural Runoff Management

Model

Nonpoint Source Model

Terrestrial Ecosystem Hydrology

Model

Other Continuous Simulation Models

Agricultural Chemical Transport

Model

Streamflow Synthesis and Reservoir

Regulation

---

TVA

HSP

Pm

ARM

NPS

TEHM

ACTMO

SSARR

National Weather Service River

Forecast Center and State of

California Dept. of Water

Resources, Sacramento,

California

Division of Water Control

Planning, Tennessee Valley

Authority, Knoxville,

Tennessee

Hydrocomp, Inc.,

Palo Alto, California

Hydrocomp, Inc.,

Palo Alto, California

Hydrocomp, Inc.,

Palo Alto, California

Hydrocomp, Inc.,

Palo Alto, California

Oak Ridge National Laboratory,

Oak Ridge, Tennessee

Agricultural Research Service,

USDA, Beltsville, Maryland

North Pacific Division, Corps

of Engineers, Portland,

Oregon
210 ● Use of Models for Water Resources Management, Planning, and Policy

TABLE D-1 (Continued)

Commnlv Used Surface Water Runoff Models

Model Name Commonly Used Acronym Originator

Conversational Streamflow Synthesis COSSARR North Pacific Division, Corps

and Reservoir Regulation Program of Engineers, Portland,

Oregon

Storage, Treatnusnt, Overflow, and STORM Hydrologic Engineering Center,

Runoff Model Corps of Engineers, Davis,

California

Quantity-Quality-Simulation Model QQS Dorsch Consult, Munich, Germany

and Toronto, Ontario

MIT Catchment Model MITCAT Dept. of Civil Engineering,

Massachusetts Institute of

Technology, Cambridge,

Massachusetts and Resource

Analysis, Inc., Waltham,

Massachusetts

SINGLE EVENT SIMULATION

U.S. Dept. of Agriculture USDAHL-74

Hydrological Laboratory Model

Problem Oriented Computer Language HYMo

for Hydrologic Modeling

Computer Program for Project TR-20

Formulation Hydrology

Urban Hydrology for Small TR-55

Watersheds

Agricultural Runoff Model AGRUN

U.S. Geological Survey Rainfall USGS

Runoff Model for Peak Flow

Synthesis

Calcul des Reseaux D’assainissement CAREDAS

(Calculation of Sewage Networks)

Agricultural Research Service,

USDA, Beltsville, Maryland

Agricultural Research Service,

USDA, Soil and Water

Conservation Research

Division, Riesel, Texas

C-E-I-R, Inc., for Soil

Conservation Service, USDA,

Washington, D. C.

Soil Conservation Service,

USDA, Washington, D. C.

Water Resources Engineers, Inc.

Walnut Creek, California

U.S. Geological Survey,

Reston, Virginia

SOGREAH, Grenoble, France

(also New York, New York)
App. D—Additional References to Models and Modeling Studies ● 211

TABLE D-1 (Continued)

Commonly Used Surf ace Water Runoff Models

Model Name Commonly Used Acronym Originator

Chicago Hydrography Method City of Chicago Bureau of

(also NERO) Engineering, Chicago,

Illinois

Chicago Flow Simulation Program FSP Metropolitan Sanitary District

of Greater Chicago, Chicago,

Illinois

HEC-1 Flood Hydrography Package

Hydrography Volume Method

Illinois Urban Drainage Area

Simulator

Road Research Laboratory Model

Storm Water Management Model

University of Cincinnati Urban

Runoff Model

HEC-1

HVM

ILLUDAS

RRL

UCUR

Hydrologic Engineering Center,

Corps of Engineers, Davis

California

Dorsch Consult, Munich, Germany

and Toronto, Ontario

Illinois State Water Survey,

Urbana, Illinois

Transport and Road Research

Laboratory, London, United

Kingdom

Metcalf and Eddy, Palo Alto,

California; University of

Florida, Gainesville,

Florida; Water Resources

Engineers, Walnut Creek,

California

Dept. of Civil Engineering,

University of Cincinnati,

Cincinnati, Ohio
212 . Use of Mode/s for Water Resources Management, Planning, and Policy

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App. D—Additional References to Models and Modeling Studies 213

TABLE D-2

Commonly Used Receiving Water Quality Models

Model Name Commonly Used Acronym Originato r

CHEMICAL REACT ION MODELS

AnalyticallyIntegrated

Streeter-Phelps Dissolved

Oxygen Equation

Lumped Parameter Nutrient

Budget Model

Indiana State Board of Health ,

Bloomington, Indiana

Center for Inland Waters,

Canadian Fisheries Research

Board, Burlington, Ontari o

Long Term Phosphorus Balance

Model

Steady-State Stream Network

Model

Simplified Stream Mode l

Simplified Estuary Mode l

Numerically Integrated

Dissolved Oxygen Sag Model

Dissolved Oxygen Sag Model

(revised version)

SCI DOSAG Modification

Estuary Model

Automatic Quality Model

SNSIM

SSM

SEM

DOSAG-I

DOSAG-3

DOSCI

Esool

AUTO-QUAL

Battelle Pacific Northwest

Labs, Richland, Washington

U.S. Environmental Protection

Agency-Region II, New York,

New York

Hydroscience, Inc.,

Westwood, New Jersey

Hydroscience, Inc.,

Westwood, New Jersey

Texas Water Development Board,

Austin, Texas

Water Resources Engineers,

Austin, Texas

Systems Control Inc.,

Palo Alto, California

U.S. Environmental Protection

Agency-Region II, New York,

New York

U.S. Environmental Protection

Agency, Washington, D. C.
214 . Use of Models for Water Resources Management, Planning, and Policy

TABLE D-2 (Continued)

Commonly Used Receiving Water Quality Models

Model Name Commonly Used Acronym Originator

River Quality Model QUAL-I Texas Water Development Board,

Austin, Texas

Dynamic Estuary Model DEM Water Resources Engineers,

Walnut Creek, California

Tidal Temperature Model TTM U.S. Environmental Protection

Agency, Pacific Northwest

Laboratory, Corvallis, Oregon

Receiving Water Model RECEIV

Module of SWMM

Receiving Water Model RIVSCI

(modification)

Receiving Water Model WRECEV

(modification)

Deep Reservoir Model DRM

Lake Ecologic Model LAKSCI

(modification of Deep

Reservoir Model)

Reservoir Water Quality Model EPARES

Hydrocomp Hydrologic Simulation HSP

Program

Water Quality Feedback Model

(HA~3 modification)

FEDBAK03

Coastal Circulation and CAFE/DISPER

Dispersion Model

Estuary Water Quality Model EXPLORE-I

Nutrient Accumulation Model SPLOTCH

Two-Diunsional Stream Mixing ---

Model

Water Resources Engineers,

Walnut Creek, California

Systems Control, Inc.,

Palo Alto, California

Water Resources Engineers,

Austin, Texas

Water Resources Engineers,

Walnut Creek, California

Systems Control, Inc.,

Palo Alto, California

Water Resources Engineers,

Austin, Texas

Hydrocomp, Inc.,

Palo Alto, California

U.S. Environmental Protection

Agency-Region II, New York,

New York

Ralph M. Parsons Laboratory,

Massachusetts Institute of

Technology, Cambridge,

Massachusetts

Battelle Pacific Northwest

Labs, Richland, Washington

U.S. Environmental Protection

Agency, Rochester, New York

Water Resources Division, U.S.

Geological Survey,

Washington, D. C.
App. D—Additional References to Models and Modeling Studies ● 215

TABLE D-2 (Continued)

Commnly Used Receiving Water Quality Models

Model Name Commonly Used Acronym Originator

Outfall Plume Model PLUME U.S. Environmental Protection

Agency, Pacific Northwest

Laboratory, Corvallis, Oregon

Willamette River Model WIRQAS Water Resources Division, U.S.

Geological Survey,

Washington, D. C.

Estuary Hydrodynamic/ HYD/SAL

Salinity Model

ECOLOGIC MODELS

(All Numerically Integrated)

River Quality Model QUAL-11

(QUAL-I modification)

Lake Ecologic Model LAKECO

(DRM modification)

Estuary Ecologic 140del ECOMOI)

Estuarine Aquatic Ecologic ESTECO

Model

Lake Phytoplankton Model LAKE-1

Eutrophic Lake Quality Model ---

Lake Ecologic Model CLEAN<LEANER

Water Quality in RiverReservoir SystemsWQRRS

Narragansett Bay Hydrodynamic ---

Model

Texas Water Developnwnt Board,

Austin, Texas

Water Resources Engineers,

Walnut Creek, California

Water Resources Engineers,

Walnut Creek, California

U.S. Environmental Protection

Agency, Washington D. C.

Texas Water Development Board/

Water Resources Engineers,

Austin, Texas

Department of Civil Engineering

Manhattan College, New York,

New York

Battelle Pacific Northwest

Labs, Richland, Washington

International Biological Program,

Rensselaer Polytechnic

Institute, New York

U.S. Army Corps of Engineers,

Hydrologic Engineering

Center, Davis, California

Department of Ocean

Engineering, University of

Rhode Island, Narragansett,

Rhode Island
Appendix E

Tables of Responses to OTA Survey of

Actual and Potential State-Level Model Use

OTA surveyed State agency employees in June, 1980 to determine their current use of models

and their perceptions of potential model use; data from Part I of this survey are tabulated in the

following pages. The respondents were asked to indicate their use of models in 33 water resource

issue areas (left-hand column) for three categories of use (across the top of the tables): A) operations and management, B) planning and policy, and C) other. In these tables, the letter ‘X’

represents some model use, and ‘O’ indicates extensive model use. The fourth category at the

top of the tables, labelled ‘N, reports instances in which State agency personnel specifically indicated that models are not used, or that no potential for model use exists.

216
App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use 217

ALABAMA ALASkA ARIZONA

Exist ing Potential Existing Potential Existing Potential

ABC N ABC N ABC N ABC N ABC N ABC N

1. Flood Forecast. x x x x x x

2. Drought/L.Flow x x x x x x x x

3. Streamflow Reg. X X x x x x x x

4 . Instream Flow x x x x x x x x

5. Dem. Water S. x x x x x x x x

6, 1rr. Agri. x x x x x

7. Offatream Use x x x x x x x x

8 . W. Use Effic. x x x x x x x

9. Urban Runoff x x x x x x x x

10. Erosion/Seal. x x x x x x x x

11. Salinity x x x x x x

12. Agrlc. Runoff x x x x x x x x

13. Airborne Poll. x x x x x x

14. Waste L. Alloc . O o x O o x x x x x

15. Thermal Poll. x x x x x

16. Toxic Materials x x x x x x x

17. Drink.Water Qual. x x x x x x

18. W.Q. Impacts x x x x x x x

19. G.W. Supplie8 x x x x x x x x

20. Conjunct. Use x x x x o x x

21. Accid. Contain. x x x x x x x x

22, Ag . Poll.-gow. x x x x x x x x x

23. W. Disposal-g.w. x x x x x x x x x

24. Salt W. Intrus . x x x x x x x x

25. Water Pricing x x “ x x

26. Costs/Poll.Con. x x x x

27. Benefit/Cost x x x x

28. Dev. Impllcst. x x x x

29. Forecast. Use x x x x x x

30. Social Imp . x x x x

31. Risk/Benefit x x x x

32. Comp. W. Use x x x x x x

33. Unified R.B.M. x x x x x x x

84-589 D - 82 - Is
218 ● Use of Models for Water Resources Management, Planning, and policy

ARKANSAS CALIFORNIA CDLORADO

Exist ing Potential — Existing Potential Existing Potential

ABC N ABC N ABC N ABC N ABCl! l ABC N

10 Flood Forecast. x x O x x x x

2 . Drought/L.Flow x x x x x x x x

3. Streamflow Reg, 0 0 0 0 x x

4. Instream Flow o x 00 x x

5. Dem. Water S. 0 0 x x x x

60 Irr . Agr lo 0 0 x x x x

7. Offstream Use x x x x x

8e W. Use Efflc. 0 0 x x x x

9. Urban Runoff x x x x x

10. Erosion/Seal. x x x x x x x x

1 10 Salinit y x X o x x x

12. Agric. Runoff x x x x x x

13. Airborne Poll. x x x x

14. Waste L. Alloc. X X x x x x x x x x

15. Thermal Poll. x x x x

16. Toxic Materials x x x x x x

17. Drink.Water Qual. x x x x x x x x

18. W.Q. Impacts x x x x x x x x

19. G.W. Supplies x x x x x x o 0

20. Conjunct. Use x x x x x x o 0

21. Accid. Contain. x x x x x

22, Ag ● Poll.-g.w . x x x x x x

23. W. Disposal-g.w. x x x x x x

24. Salt W. Intrus. xx x x x x x

25, Water Pricing x x x x x

26. Costs/Poll.Con. x x x x

27. Benefit/Cost x x x x x

28. Dev. Implicat. x x x x

29. Forecast. Use x x x x x

30. Social Imp, x x x x

31. Risk/Benefit x x x x x

32. Comp. W. Use x x x x x x

33. Unified R.B.M. x x 0 0 x x
App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use 219

CONNECTICUT DELAWARE FLORIDA

Existing Potential Exist ing Potential Existing Potential

ABC N ABC N ABC N ABC N ABC N ABC N

10 Flood Forecast. XX x x x x x x

2. Drought/L.Flow x X o x O x x x x x

3. Streamflow Reg. X x x x 0 0 x x

4. 1nstream Flow x x x x x x x

5* Dem. Water S . x x x x x x x x x

6. Irr. Agri. x x x x x

7. Offstream Use x x x x x x

8e W. Use Effic. x x x x x

9. Urban Runoff x x x x x x x x x

10. Erosion/Seal. x x x x x xx

11. Salinity o x x x x x x

12. Agric. Runoff x x x x x x x

13. Airborne Poll. x x x x x x x x

14. Waste L. Alloc . O o x o x x x

15. Thermal Poll. X x o x x x

16. Toxic Materials x X o x x xx x x

17. Drink.Water Qual. X x x x x x

18. W.Q. Impact s x x X o x x x x

19. G.W. Supplies x O o x x x x x x x

20. Conjunct. Use x O o x x x x x x

21. Accid. Contain. x x x x x x x x x

22. Ag. Poll.-g.w. x x x x x x

23. W. Disposal-g.w. X x x x x x x x x x

24. Salt W. Intros. x x x x x x x x x

25. Water Pricing x x x x x x x

26. Costs/Poll. co. x x x x

27. Benefit/Cost x x x x x x x

28. Dev. Impli=t. x x x x x x x

29. Forecast. Use x x x x x x

30. Social Imp. x x x x x x

31. Risk/Benefit x xx x xx

32. Comp. W. Use x x x x x x x

33. Unlfled R.B.M. x x x x x x x
220 ● Use of Models for Water Resources Management, Planning, and Policy

GEORGIA HAWAI1 IDAHO

Exi.sting Potential Existing Potential Existing Potential

ABC N ABC N ABC N ABC N ABC N ABC N

1. Flood Forecast. x x x x x x

2. Drought/L.Flow x x x x x x x

3. Streamflow Reg. x x x x x x x

4 . Instream Flow x x x x x x

5. Dem. Water S. x x x x x x x x

60 Irr. Agrl. x x x x x

7. Offstream Use x x x x x

8. W. Use Effic. x x x x x x x

9. Urban Runoff x x x x x x x

10. Erosion/Seal. x x x x x x x

1 10 Salinit v x x x x x x x

12. Agric. Runoff x x x x x x x x

13. Airborne Poll. x x x 0 0 0 0

14. WasteL. Alloc. 0 0 0 0 x x x o x x x

15. Thermal Poll. x x x x x x

16. Toxic Materials x x x x x x x x

17. Drink.Water Qual. x x x x x x x

18. WeQ . Impacts x x x x x x x x

19. G.w. Supplies o x x x x x x x x

20. Conjunct. Use x x x x x x x

21. Accid. Contain. x x x x x x x x

22. Age Poll.-g.w. x x x x x x x x

23. W. Msposal-g.w. x x x x x x x x

24. Salt W. Intrus. x x x x x x x

25. Water Pricimz x x x x x x

26. Costs/Poll.Con. x x x x x x x x

27. Benefit/Cost x x x x x x x x

28. Dev. Im~licat. x x x x x

29. Forecast. Use x x x x x x x x

30. Social Imp. x x x x x x

31. Risk/Benefit x x x x x x x x

32. Comp. W. Use x x x x x x x x

33. Unified R.B.M. 0 0 0 0 x x x x x x
App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use ● 221

ILLINOIS INDIANA IOWA

Existing Potential Existing Potential Existing Potential

ABC N ABC N ABC N ABC N ABC N ABC N

1. Flood Forecast. X X x x O o x O o x X o x

2. Drought /L. Flow x x x x x x x x x x x x

3. Streamflow Reg. X X x x x x x x x

4. Inatream Flow x x x x x x x x

5. Dem. Water S. x x x x x x x x x x

6. Irr. Agri. x x x x x x x

7. Offstream Use x x x x x x x

8. W. Use Effic. x x x x x x x x x x

9. Urban Runoff x x x x x x

10. Erosion/Seal. x x x x x x x x

11. Salinity x x x x x x

12. Agric. Runoff x x x x x

13. Airborne Poll. x x x x x

14. WasteL. Alloc. X x x 0 0 o x x

15. Thermal Poll. x x x x x

16. Toxic Materials x x x x x

17. Drink.Water Qual. x x x x x

18. W.Q. Impacts x x x x x

19. G.W. Supplies x x x x x x x x

20. Conjunct. Use x x x x x x x x x

21. Accid. Contain. x x x x x x x

22, Ag . Poll.-g.w. x x x x x x x

23. W. Disposal-g.w. x x x x x x

24. Salt W. Intrus. X x x x

25. Water Pricing x x x x x x

26. Costs/Poll.Con. x x x

27. Benefit/Cost x x x x x

28. Dev. Implicat. x x x x x

29. Forecast. Use x x x x x x x

30. Social Imp. x x x

31. Risk/Benefit x x x x

32. Comp. W. Use x x x x x x

33. Unified R.B.M. x x x x x x
222 ● Use of-Models for Water Resources Management, Planning, and Policy

KANSAS KENTUCKY LOUISIANA

Existing Potent Ial Existing Potent ial Existing Potential

ABC N ABC N ABC N ABC N ABC N ABC N

1. Flood Forecast. x x x x x x o x x x

2. Drought/L.Flow x x x x x X o x x x x x x

3. Streamflow Reg. X X x x x x x o 0

4. Instream Flow x x x x x x x x x x

5. Dem. Water S. x x x x x x x x x x x x

6- Irr. Agri. x x x x x x x x x

7. Offstream Use x x x x x x x x x x x

8. W. Use Effic. x x x x x x x x x x

9. Urban Runoff x x x x x x x x x x

10. Erosion/Seal. x x x x x x 0 0 0 x x x

11. Salinity x x x x x x x x x x x

1 2 . Agric. Runoff x x x x x x x x x x

13. Airborne Poll. x x x x x x x x x x

14. WasteL. Alloc. X x x x x x x x o x x x

1 50 Thermal Poll. x x x x x x x x x

16. Toxic Materials x x x 0 0 0 x x x x

17. Drink.Water Qual. x x x 0 0 0 x x x x

18. W.Q . Impacts x x x x 0 0 0 x x x x

19. G.W. Supplies x x x x x x x x 0 0 0 x x 0 0

20. Conjunct. Use x x x x x x x x x x 0 0

21. Accid. Contain. x x x x x x x x x

22. Ago Poll.-g.w. x x x x x x x x

23. W. Disposal-g.w. x x x x x x x x x

24. Salt W. Intrus. x x x x x x x

25. Water Pricing x x x x x x x x x

26. Costs/Poll.Con. x x x x x x x x x

27. Benefit/Cost x x x x x x x x

28. Dev. Implicat. x x x x x x

29. Forecast. Use x x x x x x x x x

30. Social Imp. x x x x x

31. Risk/Benefit x x x x x x

32. Comp. W. Use x x x x x x x x x

33. Unified R.B.M. x x x x x x x x x x
App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use ● 223

MAINE MARYLAND MASSACHUSETTS

Exist ing Potential Existing Potential Existing Potential

ABC N ABC N ABC N ABC N ABC N ABC N

10 Flood Forecast. XX x x x x x x x x

2. Drought/L.Flow x x x x x x

3. Streamflow Reg. XX x x x

4. Instream Flow x x x x x x

5. Dem. Water S. x x x x x

6. 1rr. Agrl. x x x x x

I

7. Offstream Use x x x x

8. W. Use Effic. x x x x x x x

9. Urban Runoff x x x x x x x x x

iO. Erosion/Seal. x x x x x x x x x

11. Salinity x x x x x x x x x x

12. Agric. Runoff x x x x x x x x x x

13. Airborne Poll. x x x x x x x x x

14. Waste L. Alloc. x x x x x x x x x x x

15. Thermal Poll. x x x x x x x x

16. Toxic Materials x x x x x x x x

17. Drink.Water Qual. X X x x x x x x x

18. W.Q. Impacts x x x x x x x x x

19. G.W. Supplies x x x x x x x x x x

20. Conjunct. Use x x x x x x x x

21. Accid. Contain. x x x x x x x x x

22. Ag. Poll.-g.w. x x x x x x x x x

23. W. Disposal-g.w. x x x x x x x x x

24. Salt W. Intrus. x x x x x x x

25. Water Pricing x x x x x x x

26. Costs/Poll.Con. x x x x x x

27. Benefit/Cost x x x x x x x

28. Dev. Implicat. x x x x x x

29. Forecast. Use x x x x x x x

30. Social Imp. x x x x x x

31. Msk/Benefit x x x x x x x

32. ComD. W. Use x x x x x x x
224 Use of Models for Water Resources Management, Planning, and Policy

MICHIGAN MINNESOTA MISSISSIPPI

Existing Potential Existing Potential Existing Potential

ABC N ABC N ABC N ABC N ABC N ABC N

1. Flood Forecast. x x x x x x x x

2 . Drought/L.Flow x x x x x x x x

3. Streamflow Reg. x x x x x x x x

4. Instream Flow x x x x x x x x x

5* Dem. Water S. x x x x x x x

6. Irr. Agri. x x x x x x x x

7. Offstream Use x x x x x x x

8. W. Use Effic. x x x x x x x

9. Urban Rmoff x x x x x x x x x x x

10. Erosion/Sed. x x x x x x x x x x x

11. Salinity x x x x x x x

12. Agric. Rtmoff x x x x x x x x x x

13. Airborne poll. x x x x x x x x x x

14. Waste L. Alloc. x x x o x x x x X o x x

15. Thermal Poll. x x x x x x x x x x x

16. Toxic Materials x x x x x x x x x x x

17. Drink.Water Qual. x x x x x x x x x

18. W.Q. Impacts x x x x x x x x x x x

19. G.W. Supplies x x x x x x x x x x

20. Conjunct. Use x x x x x x x x x x

21. Accid. Contain. x x x x x x x x x x x

22. Ago Poll.-g.w. x x x x x x x x x x

23. W. Disposal-g.w. x x x x x x x x x x

24. Salt W. Intrus. x x x x x x

25. Water Pricing x x x x x x x

26. Costs/Poll.Con. x x x x x x x

27. Benefit/Cost x x x x x x x

28. Dev. Impliat. x x x x x x x

29. Forecast. Use x x x x x x

30. Social Imp. x x x x x x

31. Risk/Benefit x x x x x x

32. Comp. W. Use x x x x x x x x

33. Unified R.B.M. x x x x x x x x
App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use 225

MISSOURI MONTANA NEBKASKA

Existing Potential Existing Potential Existing Potential

ABC N ABC N ABC N ABC N ABC N ABC N

1. Flood Forecast. x x x x o x o x x x

2. Drought/L. Flow x x x x o

3. Streamflow Reg. x x x x o x x

4. Instream Flow x )$ x x x x x x

5. Dem. Water S. x x x x x x

6. Irr. Agri. x x x x x x x x

7. Off stream Use x x x x x

8. W. Use Effic. x x x x x x x

9. Urban Runoff x x x x

10. Erosion/Seal. x x x x x

11. Salinity x x x x

12. Agric. Runoff x x x x x x x

13. Airborme Poll. x x x x x x x x x x x

14. Waste L. Alloc . x x x x

15. Thermal Poll . x x x x

16. Toxic Material s x x x x

17. Drink. Water @al. x x x x x x

18. W .Q. Impacts x x x x x x x

19. G.W. Supplies x x x x x x 0 0 X o

20. Conjunct. Use x x x x x x o x x x

21. Accld. Contain. x x x x x x

22. Ag . Poll. -g. w. x x x x x x x x x x

23. W. Disposal-g .w. x x x x

24. Salt W. Intrus. x x x x x

25. Water Pricing x x x x x x

26. Costs /Poll .Con. x x x x x

27. Benefit/Cost x x x x

28. Dev. Impli=t. x x x x x

29. Forecast. Use x x x x

30. Social imp. x x x x x x x

31. Risk/Benefit x x

32. CoIQp. W. Use x x x

33. Unified R.B.M. x x x x
226 Use of Models for Water Resources Management, Planning, and policy

NEVADA NEW HAMPSHIRE NEW JERSEY

Existing Potential Existing Potential Existing Potential

ABC N ABC N ABC N ABC N ABC N ABC N

10 Flood Fore-st. XO x x

2. Drought/L.Flow x x X o

3 . Streamflow Reg. X X o

4 . Instream Flow X o o

5. Dem. Water S. x x x x x

6. Irr. Agri. x x x

7. Offstream Use x x x

8. W. Use Effic. x x x x x

9. Urban R-off x x x x x

10. Erosion/Seal. x x x x x x

11. Salinity x x x x x x x x x x

12. Agric. Runoff x x x x x x x

13. Airborne Poll. x x x x x x

14. Waste L. Alloc. O 0 x x x x x x x x

1 50 Thermal Poll . X o x x x x

16. Toxic Materials XX x x x x x x

17. Drink.Water Qual. X x x x x x x

18. W. Q. Impacts 0 0 x x x x x

19. G.W. Supplies x x x x x x x

20. Conjunct. Use x x x x x x x

21. Accid. Contain. x x x x x x

22. Ago Poll.-g.w. x x x x x

23. W. Disposal-g.w. x x x x x x

24. Salt W. Intrus. x x x x

25. Water Pricing x x x x x x x x

26. Costs/Poll.Con. x x

27. Benefit/Cost X o x

28. Dev. Impli@t. X x x

29. Forecast. Use x x x

30. Social Imp. x x

31. Risk/Benefit x x

32. Comp. W. Use x x x x x

33. Unified R.B.M. x x x x x
App. E— Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use . 227

—.————.-——.——— —.—

NEW MEXICO NEW YORK NORTH CAROLINA

Existing Potential Existing Potential Existing Potential

ABC N ABC N ABC N ABC N ABC N ABC N

10 Flood Forecast. X x x x x x x x x

2. Drought /L. Flow x x x X o x x x x

3* Streamflow Reg. X x x o x x x x x

4. Instream Flow x x o x x x x x

5. Dem. Water S. x x x x x x x x

6. 1rr. Agri. x x x x x x x x x

7. Off stream Use x x x x x x x x

8. W. Use Effic. x x x x x x x x x

9. Urban Runoff x x x x x x x x

10. Erosion/Seal. x x x x x x x

11. Sallnity x x x x x

12. Agric. Runoff x x x x x x x

13. Airborne Poll. x x x x x x x x x

14. Waste L. Alloc. X X x x x x o x x x

15. Thermal Poll. x x x x x x x x

16. Toxic Materials X X x x x x x x

17. Drink. Water Oual . x x x x x x x

18. W.Q. Impacts x x x x x x x x x x x x

19. G.W. Supplies o x x x o x x x x

20. Conjunct. Use o x x x x x x x x

21. Accid. Contain . x x x x x x x

22. Ags poll.-~.ti. x x x x x x

23. W. Disposal-g. w. x x x x x

24. Salt W. Intrus. XX x x x x x x

25. Water Pricing x x x x x x x

26. Costs /Poll .Con. x x x x x x x x

27. Benefit/Cost x x x o x x x x x x

28. Dev. Implicat. x x x x x x x x x

29. Forecast. Use x x x x x x x x

30. Social Imp. x x x x x x x x

31. Risk/Benefit x x x x x x x x

32. Comp. W. Use x x x x x x x x

33. Unified R.B.M. x x o x x x x x
228 . Use of Models for Water Resources Management, Planning, and Policy

NORTH DAKOTA OHIO OKLAHOMA

Existing Potential Existing Potential Existing Potential

ABC N ABC N ABC N ABC N ABC N ABC N

1. Flood Forecast. x x 0 0 0 0 x x x

2 . Drought /L. Flow x x x 0 0 0 0 x x x

3 . Streamflow Reg. X o x 0 0 0 0 x x x

4. Inatream Flow x x x x x x x x x

5. Dem. Water S. x x x x x x x x x

6. Irr. Agri. x x x x x x x x

7. Off stream Use x x x x x x x x x

8. W. Use Effic. x x x x x x x x x

9* Urban Runoff x x 0 0 x x x

10. Erosion/Seal. x x x x x x

110 Salinity x x x x x

12. Agric. Runoff x x x x x x

13. Airborne Poll. 0 0 0 0 x x x

14. Waste L. Alloc. 0 0 0 0 x x x

15. Thermal Poll. 0 0 0 0 x x x

16. Toxic Materials x 0 0 x x x

17. Drink.Water @al. x x x x x x

18. W.Q. Impacts 0 0 0 0 x x x

19. G.W. Supplies o x x x 0 0 0 0 x x x x x

20. Conjunct. Use x x x x x x x x x x

21. Accid. Contain. x x x x x x x x

22. Ag. Poll.-g.w. x x x x x

23. W. Disposal-g.w. x x x x x x x x x

24. Salt W. Intros. x x x x x x

25. Water Pricing x x x x x x

26. Costs/Poll.Con. x x x x x x

27. Benefit/Cost x x x x x x

28. Dev. Impllmt. x x x x x x x

29. Forecast. Use o x x x x

30. Social Imp. X o x x x x x x

31. Risk/Benefi t x x x x x

32. Comp. W. Use x x x x

33. Unified R.B.M. x x x x
App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use . 229

1. Flood Forecast.

OREGON PENNSYLVANIA RHODE ISLAND

Existing Potential Existing Potential Existing Potential

ABC N ABC N ABC N ABC N ABC N ABC N

x x x x x x x x x x

2* Drought /L .Flow x x x x x x x X o

30 Streamflow Reg. x x x o x x x x

4. Instream Flow x x x x x x x x

5. Dem. Water S. x x x x x x x x

6. 1rr. Agrl. x x x x x x x

7. Off stream Use x x x x x x x

8. W. Use Effic. x x x x x x

9. Urban Runoff x x x x x x

10. Erosion/Seal. x x x x x

11. Salinity x x x x x

12. Agric. Runoff x x x x x

13. Airborne Poll. x x x x x x

14. Waste L. Alloc. o x x x x x x x

15. Thermal Poll . o x x x x x x

16. Toxic Materials 0 0 x x x x

17. Drink.Water Qual . 0 0 x x x x

18. W.Q. Impact s 0 0 x x x x x

19. G.W. Supplles x x x x x x 0 0

20. Conjunct. Use x x x x x 0 0

21. Accid. Contain. x x x x x x

22. Age Poll.-g.we x x x x x

23. W. Disposal-g.w. x x x x x x x

24. Salt W. Intrus. x x x x x

25. Water Pricing x x

26. Costs/Poll.Con. x x x x x x

27. Benefit/Cost x o x x x x x

28. Dev. Implimt. x x x x x

29. Forecast. Use x x x x x

30. Social Imp. x x x x x

31. Risk/Benefit x x x x x x x

32. Comp. W. Use x x x x x x

33. Unified R.B.M. x o x x 0 0
230 Use of Models for Water Resources Management, Planning, and Policy

SOUTH CAROLINA SOUTH DAKOTA TENNESSEE

Existing Potential Existing Potential Existing Potential

ABC N ABC N ABC N ABC N ABC N ABC N

1. Flood Forecast. x x x x

2. Drought/L.Flow x x

3. Streamflow Reg. x x x x x

4. Instream Flow x x

5. Dem. Water S. x x

60 Irr. Agri. x x

7. Offstream Use x x

8. W. Use Effic. x x

90 Urban Runoff x x x x x

10. Erosion/Seal. x x x x x x x x x x

11. Salinity x x x x x x

12. Agric. Runoff x x x x x

13. Airborne Poll. x x x

14. Waste L. Alloc. O 0 x x x x o 0

15. Thermal Poll. x x x o

16. Toxic Materials X x x x

17. Drink.Water Qual. X x x x x x

18. W.Q . Impacts x x x x x x x

19. G.W. Supplies x x x o x x x

20. Conjunct. Use x x x x x x x

21. Accid. Contain. x x x x x x

22. Ago Poll.-g.w. x x x x x x

23. W. Disposal-g.w. x x x x x x

24. Salt W. Intrus. x x x x x x

25. Water Pricing x x x x x x x x

26. Costs/Poll.Con. x x

27. Benefit/Cost x x x

28. Dev. Implicat. x x

29. Forecast. Use x x

30. Social Imp. x x

31. Risk/Benefit x x

32. Comp. W. Use x x x x x

33. Unified R.B.M. x x x
App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use ● 231

TEXAS UTAH VERMONT

Existing Potential Existing Potential Existing Potential

ABC N ABC N ABC Ii ABC N ABC N ABC N

1. Flood Forecast. 0 0 x x x x x x x x x

2. Drought/L.Flow x x x x x x x x x

3. Streamflow Reg. x x x x x x x x x x x

4. Instream Flow 0 0 x x x x x x x x x

5. Dem. Water S. x x x x x x x x x x

6. Irr. Agri. X o x x x x x x x x x x x

7. Offstream Use o x x x x x x x x x x x

8. W. Use Effic. O o x x x x x x x x x x

9. Urban Runoff o x x x x x x x x x x

10. Erosion/Seal. x x x x x x x x

11. Salinity x x x x x x x x x

12. Agric. Runoff o x x x x x x x

13. Airborne Poll. x x x x x x x x x x 0 0 0 0

14. Waste L. Alloc. x x x x x x o x 0 0

15. Thermal Poll. X o x x x x x x x x x x x x

16. Toxic Materials O o x x x x x x x x x x

17. Drink.Water Qual. O x x x x x x x x x x

18. W.Q . Impacts x x x x x x x x x x

19. G.W. Supplies X o x x x x x x x x x x x x

20. Conjunct. Use X o x x x x x x x x

21. Accid. Contain. x x x x x x x x x x

22. Ag. Poll.-g.w. x x x x x x x x x

23. W. Disposal-g.w. x x x x x x x x x

24. Salt W. Intrus. x x x x x x x x x

25. Water Pricing x x x x x x x x

26. Costs/Poll.Con. x x x x x x

27. Benefit/Cost o x x x x x x

28. Dev. Implicat. o x x x x x x

29. Forecast. Use o x x x x x x x

30. Social Imp. x x x x x x

31. Risk/Benefit x x x x x x x x

32. Comp. W. Use x x x x x x x

33. Unified R.B.M. x x x x x x x
.

232 . Use of Models for Water Resources Management, Planning, and Policy

VIRGINIA WASHINGTON WEST VIRGINIA

Existing Potential Existing Potential Existing Potential

ABC N ABC N ABC N ABC N ABC N ABC N

1. Flood Forecast. x x x x X o X o

2* Drought/L.Flow x x x x x X o X o

30 Streamflow Reg. x x x x x x X o X o

4. Instream Flow x X o x x x

5. Dem. Water S. x x x x x

6. Irr. Agri. x x x x x

7. Offstream Use x x x

8. W. Use Effic. x x x x

9* Urban Rutoff x x x x x

10. Erosion/Seal. x x x x x

11. Salinity x

12. Agric. Rmoff x

13. Airborne Poll. x

14. Waste L. Alloc. X o x X o X o

15. Thermal Poll. x X o X o

16. Toxic Materials x x x x x

17. Drink.Water Qual. x

18. W.Q. Impacts x x x X o X o

19. G.W. Supplies O x x x x x

20. Conjunct. Use x x X o x o

21. Accid. Contain. x x

22. Ag. Poll.-g.we x x x

23. W. Disposal-g.w. x x o

24. Salt W. Intrus. x x x

25. Water Pricing x x x

26. Costs/Poll.Con. x

27. Benefit/Coat x x

28. Dev., Impliat. x x

29. Foreumt. Use x x x x

30. Social Imp. x x

31. Risk/Benefit x x

32. Comp. W. Use x x

33. Unified R.B.M. x x x x
App. E—Tables of Responses to OTA Survey of Actual and Potential State-Level Model Use . 233

WISCONSIN WYOMING WASHINGTON, D.C.

Existing Potential Existing Potential Existing Potential

ABC N ABC N ABC N ABC N ABC N ABC N

1. Flood Forecast. X X x x x x x x x x

2. Drought/L.Flow x x o x x x x x x x x x

3. Streamflow Reg. x x x x x x x x x x x

4. Instream Flow x o x x x x x x

5. Dem. Water S. x x x x x x x x

6. Irr. Agri. x o x x x x x x

7. Offstream Use x o x x x x x x

8. W. Use Effic. x x x x x x x x

9. Urban Runoff x x x x x x x x x x x X o

10. Erosion/Seal. x x x x x x x x x x x x

11. Salinity x x x x x x x

12. Agric. Runoff x x x x x x o x

13. Airborne Poll. x x x x x x x x

14. Waste L. Alloc. 00 x x x x x x

15. Thermal Poll . x x x x x x x

16. Toxic Materials x x x x x x

17. Drink.Water Qual. x x x x x x

18. W.Q . Impacts x x x x x x x x x x x

19. G.W. Supplies x x x x x x x

20. Conjunct. Use x x x x x x x x x x x

21. Accid. Contain. x x x x x x x x x x

22. Ag . Poll.-g.w. x x x x x x x x x x x

23. W. Disposal-g.w. x x x x x x x x x x x

24. Salt W. Intrus. x x x x x x

25. Water Pricing x x x x x x

26. Costs/Poll.Con. x x x x x x x x x

27. Benefit/Cost x x x x x x

28. Dev. Implicat. x o x x x x x

29. Forecast. Use x x x x x x x

30. Social Imp. x x x x x x

31. Risk/Benefit x x x x x x x

32. Comp. W. Use x x x x x x

33. Unified R.B.M. o x x x x x
Index
Index

Ada, Okla., 168

agriculture

as greatest user of water, 31

irrigation in, 109, 128-129

as a water pollution source, 33

aquatic life

water quality impacts on, 140-141

Argonne National Laboratory, 177

Army Corps of Engineers, 9, 11, 110, 135, 136,

157, 158

assistance to States, 99

Coastal Engineering Research Center

(CERC), 177

drought and low-flow models provided by, 109

Engineering Computer Programs Library, 60

Hydrologic Engineering Center (HEC), 10, 15,

17, 20, 51, 53, 60, 84-85, 92, 108, 177

models used by, 176-177

Office of the Chief of Engineers, 60

role in water resources, 176

thermal pollution modeling services of, 112

training programs conducted by, 106, 108

Waterways Experiment Station (WES), 177

Athens, Ga., 91

Bay St. Louis, Miss., 86

Bureau of Mines, 72

Canada

survey of environmental management simulation

models in, 201

carbon tetrachloride, 140

Catalog of Information on Water Data, 81

Center for Water Quality Modeling (see

Environmental Protection Agency)

Chase Econometrics, Inc.

macroeconomic model of, 157

Chesapeake Bay, 183, 186

Kepone in, 136

storm surges in, 186

coastal areas

index to stations in, 81

coastal zone management, 85

Colorado River Basin, 87

Colorado River Basin Salinity Control Program, 70

Congress

acts of (see legislation)

options available to, 11-12, 13-14, 16, 17-18,

20-21

Senate Select Committee on National Water

Resources, 25

Connecticut River, 7

Cooperative Instream Flow Service Group (see

Instream Flow Group

Cornell university, 6

Corps of Engineers (see Army Corps of Engineers)

Council on Environmental Quality (CEQ

models used by, 182

Department of Agriculture (USDA), 111

assistance to States, 99

drought and low-flow models provided by, 109

Economic and Statistics Service (ESS), 172

Forest Service, 71, 72, 174

Land and Water Conservation Task Force, 92

Land and Water Resources and Economic

Modeling System (LAWREMS), 17, 88,

92-93, 172

models used by, 172-176

Science and Education Administration

(SEA), 174-175

Soil Conservation Service (SCS), 75, 78, 108,

135, 136, 157, 172, 175

Department of Commerce, 82, 158

models used by, 176-177

National Oceanic and Atmospheric

Administration (NOAA), 175-176

Department of Energy (DOE)

Federal Energy Regulatory Commission

(FERC), 178

Office of Environmental Assessments, 177-178

Department of the Interior (DOI), 72, 77, 78

79, 82, 87

Bureau of Land Management (BLM), 178

Bureau of Mines, 178-179

Bureau of Reclamation, 157, 158, 180-181

Fish and Wildlife Service, 179

models used by, 178-182

Office of Surface Mining, 179

Office of Water Data Coordination

(OWDC), 80-82

Office of Water Research and Technology

(OWRT), 19, 20, 21, 79, 168, 179

State Institute Program, 79-80

University Water Research Program,

9, 10, 19, 20

U.S. Geological Survey (USGS), 181-182

Department of Transportation, 78

I.)01, (see Department of the Interior)

DRI

macroeconomic model of, 157

drought and low stream flow

forecasting of, 109, 126

237
238 . Use of Models for Water Resources Management, Planning, and Policy

economi c cand c and social issues, 29

competitive water use, 116

cost/benefit analysis, 115, 157-158

costs of pollution control, 114-115, 157

effects of pricing on water use, 114, 156-157

forecasting water use, 116, 159

models for analysis of, 152-161

regional economic development, 115-116, 158-159

risk/benefit analysis, 116, 159-160

social impact, 116

unified river basin management, 116, 161

Economic and Statistics Service (see Department of

Agriculture)

Economic Assessment Model, 158

energy development, 85

environmental impact evaluation, 85

Environmental Protection Agency (EPA), 8, 9, 13,

14, 33, 72, 78, 87, 136, 137, 138, 139,

157, 168, 172

Center for Water Quality Modeling, 17, 18, 50,

88, 91-92

Cleveland Electric Illuminating Co. v. EPA, 62

Environmental Research Laboratory, 91, 92

Holcomb Groundwater Model Clearinghouse,

14, 18

Holcomb Research Institute, 50, 88, 168

International Clearinghouse for Groundwater

Models (ICGWM), 17, 88-89

models used by, 182-185

Office of Research and Development (ORD),

90, 183

Office of Toxic Substances (OTS), 184

Office of Water Enforcement, 184-185

Office of Water Program Operations

(OWPO), 183

Office of Water Regulations and Standards

(OWRS), 183

Office of Water and Waste Management, 183

Stormwater Management Model (SWMM), 15,

20, 50, 89-91, 105, 135

thermal pollution modeling services of, 112

Executive Office of the President (EOP), 77

Executive Order No. 11988 (see flood plain

management

Federal Council for Science and Technology

Committee on Water Resources Research

(COWRR), 77

Federal Emergency Management Agency, 71, 108

models used by, 186

Federal Insurance Administration (FIA), 186

Federal Software Exchange Center (FSEC) (see

General Services Administration

Fish and Wildlife Service, 87, 110

Flander’s Bay (Long Island, N.Y. ), 41, 42, 43

flood plain management, 85, 109, 176

Executive Order No. 11988, 8, 69, 174, 175

floods

assistance to States in control of, 99

control of, 4, 30, 108, 124-126

damage from, 30, 124

distribution of information by Federal

agencies, 108

forecasting of, 108, 124-126

insurance, 109

warning systems for, 85

Forest Service (see Department of Agriculture)

GAO (see General Accounting Office)

General Accounting Office (GAO), 60, 61, 73, 74,

75, 84

survey on improving management of federally

funded computerized models, 199

General Services Administration (GSA)

Federal Property Management Regulations, 83

Federal Software Exchange Center (FSEC), 17,

18, 49, 83-84

Great Lakes, 183

polychlorinated biphenyls (PCBS) in, 141

ground water, 29, 34, 37, 85

availability of, 34, 146-147

conjunctive use of surface water and,

113-114, 146

model types available for analysis of, 151-152

model types used in resource analysis of, 144-146

pollution of, 43, 114

quality, 147-151

quantity and quality of, 143-152

saltwater intrusion in, 37-38, 40, 114

SCOPE International Assessment Project on

models of, 201

as sole source of drinking water in Long Island,

N. Y., 40

subsidence caused by withdrawal of, 147

supplies and safe yields of, 113

GSA (see General Services Administration)

Gulf Coast Hydroscience Center, 86

Holcomb Clearinghouse (see Environmental

Protection Agency)

Holcomb Research Institute (see Environmental

Protection Agency)

Hudson River

polychlorinated biphenyls (PCBS) in, 141

hydroelectric power, 4, 109

hydrologic cycle, 121

Hydrologic Engineering Center (HEC) (see Army

Corps of Engineers)

Illinois Pollution Control Board, 63

Index to Stations in Coastal Areas, 81
Index . 239

Instream Flow Group, 12, 20, 51, 87-88, 110

Interagency Advisory Committee on Water

Data, 81

International Clearinghouse for Groundwater

Models (ICGWM) (see Environmental

Protection Agency)

James River, 183

Kepone in, 136, 141

Johnson, Dr. William, 53

Kepone, 136, 141

Lakewood, Colo., 86

Land and Water Resources and Economic Modeling

System (see Department of Agriculture)

land-use planning, 85

legislation

Atomic Energy Act, 8, 70, 186

Brooks Act, 83

Clean Air Act, 137

Clean Water Act, 6, 8, 14, 70, 72, 97, 102, 110,

111, 112, 114, 115, 135, 137, 138, 139, 140,

172, 174, 175, 176, 179, 180, 182, 183, 185

Coastal Zone Management Act, 8, 69

Colorado River Basin Salinity Act, 175

Colorado River Salinity Control Act, 180

Endangered Species Act, 8, 69, 174, 180

Energy Conservation Standards for New

Buildings Act, 64

Federal Insecticide, Fungicide, and Rodenticide

Act, 184

Federal Power Act, 178

Federal Reclamation Act, 8, 69, 180, 180, 182

Federal Water Pollution Control Act, 40, 68,

138, 172

Fish and Wildlife Coordination Act, 176, 179

Flood Control Act, 8, 69, 174, 175, 176,

178, 180

Food and Agriculture Act, 174

Forest and Rangeland Renewable Resources

Act, 71

Forest and Rangeland Renewable Resources

Planning Act, 174

Intergovernmental Personnel Act, 87

National Environmental Policy Act, 8, 69, 139,

153, 176, 180

National Environmental Protection Act, 61, 186

National Flood Insurance Act, 8, 69, 71, 186

National Forest Management Act, 71, 174

Organic Act, 176

Resource Conservation Act (see Soil and Water

Resources Conservation Act)

Resource Conservation and Recovery Act, 8, 68,

97, 140, 182

Rural Clean Water Program, 175

Safe Drinking Water Act, 8, 14, 68, 72, 97, 140,

179, 182, 183, 184

Soil and Water Resource Act, 69

Soil and Water Resources Conservation Act, 8,

172, 174, 175, 179, 182

Surface Mining Control and Reclamation Act, 8,

69, 174, 179, 182

Toxic Substances Control Act, 8, 72, 140, 184

Watershed Protection and Flood Prevention Act,

174, 175

Water Research and Development Act, 8, 11, 13,

77, 79, 82

Water Resources

Water Resources

115, 172, 175,

Water Resources

Long Island, N,Y.

Development Act, 174, 180, 182

Planning Act, 8, 69, 97, 114,

178, 182, 185

Research Act, 79

as-a case study of model use, 40-43

Long Island Regional Planning Board, 6

mathematical models (see models)

Menlo Park, Calif., 86

Model Annotation Retrieval System (MARS), 89

models

access to Federal, 106

of agricultural runoff, 111, 136-137, 183

of agricultural soil/water interaction, 122

of airborne pollution, 112, 137-138

alluvial process, 123

appropriateness of, 170-171

aquatic life impact, 112-113

of aquifer characteristics, 102

Argonne Water Quality Accounting System

(AQUAS), 177

Automated Downstream Accounting Model

(ADAM), 177

baseflow, 121

Bureau of Reclamation Economic Assessment

Model (BREAM), 181

calibration of, 56-57

channel process, 123

characteristics affecting ease of using, 52-53

Chemicals, Runoff, and Erosion from

Agricultural Management System

(CREAMS), 175

clearinghouse for, 169

Colorado River System Simulation (CRSS), 185

of competitive water use, 116

for conjunctive use of ground and surface water,

113-114

constraints to use by States, 104-107

of contaminant transport, 144-146

coordination of information on, 170

coordination mechanisms for, 80-84
240 . Use of Models for Water Resources Management, Planning, and Policy

in cost/benefit analysis, 115

data availability for, 73, 105, 167-168

in data management, 29

decisionmaker understanding of, 73-74, 170

definition of, 26-30

descriptive, 28, 29-30

deterministic, 30

dissemination of, 75

documentation of, 107, 168

for drinking water quality, 112

in drought and low-flow forecasting, 109, 126

economic and social, 152-161, 166

of erosion and sedimentation, 135-136

in erosion and sedimentation studies,

33, 110, 136

evaluation of, 55-59

Exposure Analysis Modeling System

(EXAMS), 183

Federal agency publications on, 187-192

Federal agencies using, 172-186

Federal approaches to management of, 76-93

Federal expenditures on water-related, 4, 9

Federal programs using (table), 68-70

Federal use and support of water resource

models, 67-93

in flood control, 30, 124-126

in flood and drought frequency analysis, 124

general uses of, 5-8, 25-30

in ground water assessment, 34-37, 38-39, 43,

146, 165-166

of ground water flow, 144

of ground water pollution, 39

higher dimension, 167

of instream flow, 110

of instream needs, 127-128

interaction between modelers and decisionmakers,

53-55

interagency (Federal) coordination on, 75-76

in irrigation, 7, 122

issues related to, 10-21, 47-64

lack of coordination among agencies using, 9

land drainage, 122

legal aspects of, 61-64, 171

legislation associated with use of, 8

in Long Island, N. Y., 41-43

Los Alamos Coal Use Modeling System

(LACUMS), 177

maintenance of, 52, 75, 107, 169

to meet State needs, 104-105

Multiple-Objective Programing (MOP), 180

National Weather Service River Forecast System

(NWSRFS), 176

of offstream water use, 109

in operations and management, 29, 43

oversight in development of, 59-61

personnel shortage for, 105-106

in planning and policy development, 29, 41

in pollution control, 39, 112, 114-115

potential at the State level, 10

predictive, 28

prescriptive, 30

in the private sector, 167

probabilistic (stochastic), 30, 166

process, 121

of receiving-water quality, 183

references to studies of, 187-192, 202-206

in regional economic development, 39, 115-116

Regional Energy Location Model (RELM), 180

in regulation, 29

reliability and credibility of, 106-107

research and development needs on, 165-167

Return Flow Quality Simulation Model, 181

in risk/benefit analysis, 39-40, 116

of river basins, 27-28, 39, 116

for salinity control, 136

in social impact assessment, 116

standardization of, 107

statistical, 121, 123-124

State funding of, 107

State government use of, 97-116

Strategic Environmental Assessment System

(SEAS), 178

stream process, 123

in streamflow regulation, 31, 59, 109, 126-127

support services for, 9, 47-53, 84-93

of surface water flow and supply, 165

in surface water flow and supply analysis,

121-124

of surface water quality, 165

of surface water salinity, 111

System of Watershed Automated Management

Information (SWAMI), 175

of thermal pollution, 112, 139-140

of toxic materials, 34, 140

training in, 50-51

Universal Soil Loss Equation (USLE), 175

of urban runoff, 110, 123, 134-135

used by Army Corps of Engineers, 176-177

used by Council on Environmental Quality, 182

used by Department of Energy, 177-178

user assistance in, 51-52, 88-93

user support of, 74-75

validation of, 56, 57-58, 168

of wasteload allocation, 8, 33, 112, 138-139

Water Assessment System, 177

for water budgeting, 41

in water conservation, 32

in water current studies, 41-42
Index ● 241

in water pricing, 40, 114

of water quality, 140

in water use forecasting, 40, 116

Water Use Information System (WUIS), 177

Nassau-Suffolk Regional Planning Board, 40, 41

National Academy of Sciences (NAS), 79

Water Resources Research Review

Committee, 78

National Bureau of Standards (NBS), 75

study of ways to improve utility of large-scale

models, 200

National Commission on Water Quality, 138

National Dam Safety Program, 108

National Oceanic and Atmospheric Administration

(NC)AA), 108

National Pollution Discharge Elimination

System, 63

National Research Council, 11

National Science Foundation (NSF), 21, 73,

74, 75, 168

survey of federally supported mathematical

models, 199

water resources research funded by, 185

National Technical Information Service (NTIS), 17,

49, 82, 82-83

National Water Data Exchange (NAWDEX), 81-82

Nationwide Weather Service (NWS), 6, 7, 176

drought and low-flow models provided by, 109

Nationwide Urban Runoff Program, 134-135

Nebraska, 7

Nuclear Regulatory Commission (NRC), 72, 139

models used by, 186

Occoquan Reservoir (Virginia), 6

Office of Management and Budget (OMB), 12, 80

Office of Science and Technology Policy (OSTP),

12, 77, 78, 79

Office of Technology Assessment (OTA), 5, 9, 10,

11, 13, 16, 49, 50, 53, 67, 70, 73, 74, 75, 79,

84, 108

State modeling survey, 97-98

Technologies for Determining Cancer Risks From

the Environment, 140

workshops on water resource modeling, 165-171

Office of Water Data Coordination (OWDC), 80-82

Office of Water Research and Technology (OWRT)

(see Department of the Interior)

Ohio River, 140

carbon tetrachloride in, 140

OSTP (see Office of Science and

Technology Policy)

Peconic River (Long Island, N.Y. ), 41

Pecos River Basin (New Mexico), 6

Pennsylvania, 172

pollution

from agricultural runoff, 33, 41, 149-150

airborne, 33, 112

costs of controlling, 114-115

of drinking water by bacteria and viruses, 34

of drinking water by toxic chemicals, 33-34

effects on aquatic life, 33

from erosion, 33

of ground water, 39, 43, 147-152

in Long Island, N. Y., 40

point sources of, 38-141

from seawater intrusion, 150-151

thermal additions to streams, 33, 72, 112

from urban and industrial areas, 147-149

from urban storm runoff, 33

from waste disposal sites, 150

polychlorinated biphenyls (PCBS), 141

President Carter, 77

President of the United States, 77

reservoirs, 121

as multiple-purpose facilities, 6

operations, 109

sedimentation in, 136

Resources for the Future, 25

Reston, Va., 86

San Joaquin Valley (California), 172

Secretary of Interior, 11, 77

Smithsonian Scientific Information Exchange

(SSIE), 82

social issues (see economic and social issues)

Soil Conservation Service (see Department of

Agriculture)

Stormwater Management Model (SWMM) (see

Environmental Protection Agency)

streamflow regulation, 109

support services (see models)

Supreme Court, 61

surface water, 85

agricultural runoff, 111-112, 136-137

aquatic life, 112-113

availability of, 120-121

conjunctive use of ground water and,

113-114, 146

drinking water, 112

erosion and sedimentation, 110-111, 135-136

eutrophication of, 133

evaporation of, 122

flow and supply of, 29, 108-110, 119-131,

130, 165

model types used in quality analysis of, 132-134,

141-143

pollution of, 112, 132, 133, 137-138
— .

242 ● Use of Models for Water Resources Management, Planning, and Policy

quality of, 29, 110-113, 131-143, 165

salinity of, 111, 136

urban runoff, 110, 134-135

use of, 121

watershed models, 121, 121, 121

Tennessee Valley Authority (TVA), 6-7, 157

University Water Research Program (see

Department of the Interior)

U.S. Geological Survey (USGS), 9, 10, 11, 15, 20,

51, 82, 84, 108, 110, 111, 113, 135

Federal-State Cooperative Program, 86

National Training Center, 86

training programs conducted by, 106

Water Resources Division, 85-87

wasteload allocation

definition, 138

waste storage and utilization, 85

water (see specific entries, e.g. , surface water,

ground water, water resources)

water resources

activities involved in managing, 30

conservation of, 32-33, 110, 129

demand for professionals in, 9

domestic water supplies, 109-110, 128, 140

drought and low stream flow, 30, 109

effect of urban storm runoff on, 33

Federal expenditures for, 4

Federal-State cooperation on, 12-13

instream flow needs, 31, 110

irrigation, 109

issues in, 26, 30-40, 99, 101, 101-102, 102-103,

113-116

in Long Island, N. Y., 40-43

mathematical models of, 5-8, 26-30, 55-59

offstream uses of, 31, 109, 129

pollution of, 32, 33, 72, 138-141

quality of, 85

research on, 11-12, 77, 78-80

sedimentation in waterways, 33

State research institutes on, 79-80

State use of models for, 101

streamflow regulation, 31-33, 59, 109

Water Resources Council, 12, 30, 81, 158, 172, 177

models used by, 185

Principles and Standards of, 153

Water Resources Scientific Information Center

(WRSIC), 16, 18, 49, 82

World Meteorological Organization, 59

Us. GOVERNMENT PRINTING OFFICE : 1982 0 - 84-589