GEOLOGICAL SURVEY CIRCULAR 539 

Flood Information for 

Flood-Plain Planning 

By Conrad D. Bue 

--------------------------------~ GEOLOGICAL SURVEY CIRCULAR 539 

Washington 1967 
United States Department of the Interior 

STEWART L. UDALL, Secretary 

Geological Survey 

William T. Pecora, Director 

se¢ond printing 1967 

Free on application to the U.S. Geplogical Survey, Washington, D.C. 20242 
Abstract----------------------------------

Introduction -------------------------------

The flood problem-------------------------

Flood-plain regulation----------------------

Land-use zoning - - - - ----- - - - - - ----- - ---- -

Flood proofing---------------------------

Flood forecasting ------------------------

Hydrologic investigations atlases ------------

CONTENTS 

Page 

1 

1 

1 

2 

3 

4 

4 

4 

Page 

Basic data on floods---------------------.,.-- 6 

Other programs related to flood-plain 

planning--------------------------------- 7 

Corps of Engineers ---------------------- 8 

Tennessee Valley Authority--------------- 8 

Zoning by local governments, by John E. 

McCall---------------------------------- 8 

Selected references------------------------ 9 

ILLUSTRATIONS 

Page 

Figure 1. Photograph showing flood of March 12, 1963, on North Fork Kentucky River at 

Hazard, Ky------------------------------------------------------------------------- 2 

2. Part of a flood inundation map, showing how the flooded area is delineated----------------- 5 

3. Division of the 48 conterminous States into parts and subparts---------------------------- 7 

Flood Information for Flood-Plain Planning 

By Conrad D. Bue 

ABSTRACT 

Floods are natural and normal phenomena. They are catastrophic simply because man occupies the flood plain, the highwater channel of a river. Man occupies flood plains because it is 

convenient and profitable to do so, but he must purchase his occupancy at a price-either sustain flood damage, or provide floodcontrol facilities. Although large sums of money h':lve been, and 

are being, spent for flood control, flood damage continues to mount. 

However, neither complete flood control nor abandonment of the 

flood plain is practicable. Flood plains are a valuable resource 

and will continue to be occupied, but the nature and degree of 

occupancy should be compatible with the risk involved and with 

the degree of protection that i.s practicable to provide. It is primarily to meet the needs for defining the risk that the floodinundation maps of the U.S. Geological Survey are prepared. 

I NTRODUCTI 0 N 

Where flood damages have been relatively minor, 

they are usually permitted to continue. In some places 

this choice has been arrived at by a study which showed 

that the cost of flood protection was greater than the 

anticipated reduction in damage. Where flood damages 

become unbearably high, something is ultimately done 

to lessen them. Just what is done depends upon the 

nature of the developments on the flood plain and the 

physical and economic feasibility of providing protection. 

By the Flood Control Act of 1936, the Federal Government first assumed responsibility for flood control 

on a national scale. At that time the Congress stipulated 

that the Federal Government would participate only in 

projects designed to protect cities and communities 

against catastrophic floods. But subsequent floodcontrol acts became progressively broader in scope, 

and now these acts, although still referred to as floodcontrol acts, constitute the main body of Federal law 

dealing with the development, utilization, and conservation of the ·Nation's water resources. "Floodcontrol law has become the legislative basis for the 

broadest and greatest programs of public works and 

resource development ever undertaken by the United 

States" (U.S. Senate, 1960). 

In the last two or three decades much thought has 

been given to flood zoning as a means of abating flood 

losses and of reducing the mounting requirements for 

flood control. "Flood zoning" is the general term ap1 

plied to the various measures designed to control the 

use of the land within the flood plain. Flood zoning reduces damage by requiring that the flood plain be used 

for purposes not subject to flood damage, and by providing for an unobstructedfloodway. Thefloodimundation maps of the U.S. Geological Survey are intended 

to aid those engaged in planning the best use of a river 

flood plain. 

The purpose of this circular is to give the reader 

a broad view of the flood problem and to acquaint him 

with the nature and use oftheflood-inundationmaps of 

the U.S. Geological Survey. 

THE FLOOD PROBLEM 

Floods have always been recurrent events; they are 

natural and normal phenomena. Floods become a problem to man only when he competes with rivers for the 

use of the flood plains, the high-water channels of 

rivers (fig. 1). This competition between man and 

the rivers has been long and costly. 

There is no complete record of flood damages that 

includes the effects of both the great and the ordinary 

floods. However, White ( 1958) gives an estimate of 

$329 million as an average annual loss for the period 

1936-55, based on figures from the U.S. Weather Bureau adjusted to the 1957 index. Loss oflife as a consequence of floods has diminished during the past half 

century, owing to improved communication facilities, 

greater and more immediate availability of medical 

aid and rescue operations, the Weather Bureau's 

warning system, and perhaps a greater awareness of 

the flood hazard on the part of the public. 

Property damage, on the other hand, is generally 

increasing, despite the expenditure of several billion 

dollars for flood control since the enactment of the 

Flood Control Act of 1936. Hoyt and Langbein (1955) 

found evidence of increased flooding during the past 

half century, but were mindful of the "long-term though 

irregular cycles in river behavior of which the past 

fifty years may represent a :rising phase, which may 

again be reversed." Of the increase in reported flood 

damage, they ascribe about 45 percent to the increase 

in property values, 25 percent to an increase in flooding, and 30 percent to an increase in building and other 

uses on flood-hazard lands. 
Figure 1.-Flood of March 12, 1963, on North Fork Kentucky River at Hazard, Ky. A graphic example of 

man and nature competing for a river flood plain. Photograph by "Courier-Journal and Louisville 

Times. " I 

Flood problems, like our problems of water supply, 

are without any clear-cut solution. There are various 

approaches to the flood problem, all of which hi ve 

been used and found effective to a degree. But no one 

measure is adequate in itself, except perhaps in minor 

floods, .and if the flood is of rare magnitude all measures fail as a s~lution. I 

Solutions to flood problems fall into two broad categories-structural and nonstructural. Structural solutions include reservoirs, levees, floodways, and channel improvement; nonstructural consists mainly of 

flood plain regulation. This report is concerned with 

flood-plain regulation and with the use of Geological 

Survey maps and reports in defining flood risk. 

FLOOD-PLAIN REGULATION 

The purpose of flood-plain regulation is to obtain 

beneficial use of flood plains with a minimum of fldod 

damage and a minimum of expense for flood protec2 

tion. In other words, the objective offlood-plainregulation is to promote uses of the flood plain so that the 

benefits derived from its use exceed the flooddamage 

plus the cost of providing a specified degree of protection. Indiscriminate use of floodplains invites great 

property damage and human suffering, including loss 

of life, whereas at the other extreme, complete abandonment of flood plains would be a sacrifice of a valuable national resource; the answer lies somewhere 

between those extremes, depending upon circumstances. 

The techniques of flood-plain regulation include (1) 

land-use zoning, and (2) flood proofing. Application of 

these techniques depend on delineation of flood zones 

on a map. A subsequent section entitled "Hydrologic 

Investigations Atlases " describes how Geological Survey maps can aid in defining flood zones. 

Non structural measures may be used effectively and 

profitably in conjunction with structural measures. 
For example, land-use zoning and flood proofing might 

be practiced in conjunction with a flood-control reservoir; a .smaller reservoir might thus be required, or, 

a certam amount of potential reservoir storage might 

be released for other uses. 

LAND-USE ZONING 

Land-use zoning is the restriction of the use of 

flood-prone lands to minimize flood damage. "Zoning 

has been the most widely advocated of all the methods 

of regulating development in flood plains. This method 

has been proposed repeatedly for the past thirty years, 

but probably no more than eight communities had effective flood-plain zoning before 1955. ***The reasons 

for non-use revolve mostly around (1) lack of basic 

data and (2) questionable legality" (Murphy, 1958). The 

lack of basic data is rapidly being corrected through 

the flood-information activities of the Geological Survey, th~ Corps of Engineers, and the Tennessee Valley 

Authonty, and the question of legality has largely 

ceased to be a valid argument against zoning. 

Flood protection can seldom be complete. There is 

always a probability that a greater flood will occur 

than . h~s been experienced in recorded history. The 

proVISIOn of even a degree of flood prevention invites 

continued and increased use of the protected area· 

people tend to confuse a degree of protection with com~ plete protection. Then when a flood occurs in excess 

of that for which protection has been provided, damage may be greater than if there had been no protection. Logically, then, some limitations should be placed 

on the type and degree of use of a protected area 

(Leopold and Maddock, 1954). 

~s discussed by Hoyt and ~angbein (1955): "The 

pnmary goal of flood zoning [that is, land-use zoning] 

must be to prevent unwarranted constrictions that reduce the ability of the channel to carry water and thereby add to the height of floods. Thus there should be 

main~ained a channel with capacity adequate to carry 

the d1scha~g.e of a certain specified flood depending on 

local cond1t10ns. Where this is to be done "encroachment lines" b~yond which no structure may extend, 

~ust be established after suitable field surveys. This 

1s not to protect the structures, but so that the structures will not cause damage to other property.*** In 

general, therefore, the practice of setting encroachment limits is a balance between the principle of 

complete exclusion arid no restrictions whatever. Coupled with regulations for flood-plain use outside the 

encroachment limits, it provides a fully economic arrangement." 

Zoning, as described by Hoyt and Langbein requires "*** cons1 'd erauon . o f f 1 . oodmg as a guide • to the use of 

land. Most agriculture, grazing particularly, represents justifiable use of flood lands. So do parks and 

lakes built to replace channel storage lost when buildings and protective works were put up on the flood 

plain.*** Home building, on the other hand, is an ex3 

ample of the most unwise use offloodland. The use of 

flood land must be based, first, on what effects a particular use may have on flood heights, i.e., whether it aggravates the flood problem for users and others***." 

The uses of the flood plain relate directly to the 

frequency of flooding, and regulations usually recognize certain "flood zones," defined as' bandP within 

which floods occur with comparable frequency. Permissible land uses within each flood zone wo·1ld then 

correspond to the frequency of flooding in that zone. 

For example, a flood zone whose upper limit is the 

1.5-year flood would correspond to the channel itself, 

since the bankfull stage is reached with an average 

frequency of once in a 1.5-year period. In ttis flood 

zone, no obstructions would be permitted that would 

interfere with the free flow of water, and particularly 

bridges would be designed so as not to caw:;e back 

water. A flood zonecomprisingtherangefromthe 1.5-

to 10-year floods would also be kept free of f:.xed obstruction, and reserved for such uses as agriculture, 

parks, and roads. In a flood zone for the 10- to 100-

year interval, buildings might be permitted, either 

with first floor above the 100-year level or flood 

proofed. These possibilities are only examples of the 

application of flood maps to the delineation of flood 

zones, and of flood zones to flood-plain regulation. 

According to Hogan ( 1963 ), "The constitutionality of 

zoning as a proper exercise ofthepolicepower l'as been 

established for some time. ***While their [zoning ordinances] application to particular situations is sometimes held so arbitrary as to violate the due process 

clause, zoning ordinances have been held valid in virtually every case in which the zoning was reasonably 

related to the public health, safety, or general welfare." 

Irr further discussing the legal aspects cf floodplain zoning, Hogan states: "In the final analysis each 

ordinance setting up a land-use regulation must, in 

the words of the courts, "be reasonable and rot arbitrary." The principal criterion as to the reasonableness of flood-plain zoning ordinances involves a determination of the extent of the flood hazard. In other 

words, the regulations must bear a reasonable relation 

to the engineering data. In order to be reasorable the 

area, extent and elevation determinations of the land 

placed in the flood plain zone should be bas~d upon: 

historical evidence of flooding; a computed frequency 

of floods; an engineering study of flood potential; an 

analysis of the degree of flood protection afforded by 

other methods of regulation; the degree of flood protection offered by engineering structures and whether 

or not development in the immediate future will increase or lessen the runoff. The uses to be p~rmitted 

on the land subject to flooding should also take into 

consideration the anticipated growth of the area and the 

availability of non-flood land sufficient for t;e needs 

of the community. Once a legislative finding offact as 

to flood hazard has been made, although not ccnclusive 

upon the courts, it will be accorded judicial co"'sidera-
tion and deference. Therefore, there appears to be no 

legal reason why flood-plain zoning is any different 

from any other type of zoning except for the rather 

extensive amount of engineering research which must 

be conducted in order to determine the area and elevation of the land to be included in any such district. 11 

FLOOD PROOFING 

Flood proofing is defined as adjustments to structures and contents to reduce flood damage. In some 

small flood-damage reduction programs, flood proofing alone may suffice; in most flood-damage reduction 

programs; flood proofing can be used effectively in 

conjunction with other measures. 

Sheaffer ( 1960) gives three main classes of floodproofing measures: permanent, contingent, and emergency. Permanent measures provide permanent protection against the flood for which they were designed, 

such as pe:r;manently closing openings in outer walls 

with impervious material or installing automatic gatevalves on sewer lines in such a manner that when flood 

waters back up, the back pressure closes the valve. 

Contingent measures require action to make them 

operative, such as a sewer valve that must be closed 

manually, or a show window equipped with a removable bulkhead that must be installed when a flood is 

imminent. Emergency measures are either improvised when needed or carried out according to prior 

emergency plans, such as temporary removal of merchandise from a threatened level, or rescheduling 

freight shipments to reduce the amount of damageable 

goods on hand. 

FLOOD FORECASTING 

Flood forecasting, although not a measure in itself, 

plays an important role in flood-damage reduction. It 

may save lives by enabling residents to evacuate the 

flood plain, and save property by enabling residents 

to put flood-proofing measures into effect. 

Flood forecasting was started in the United States 

in 1871 by the Signal Service of the U.S. Army. In 1890 

that activity was transferred to the then newly established U.S. Weather Bureau, and it is now performed 

at many River Forecast Centers of the Weather Bureau 

in the basins of large rivers. It is not possible to 

evaluate the dollar benefits of forecasting with any 

degree of accuracy, but Hoyt and Langbein (1955) estimated that the savings accredited to this service 

approximated 10 percent of the total annual flood loss. 

Undoubtedly many lives, too, have been saved through 

forecasting, although experience has shown that many 

people prefer to remain at home and face the flood 

rather than to move out, 

Forecasts that are made public must be dependable; 

a poor or misleading forecast is worse that none. As 

pointed out by Hoyt and Langbein, a forecast that is 

4 

too low catches many unprepared who might otherwise 

have been ready, and a forecast that is too high requires costly and unnecessary expenses and anxiety, 

and may result in the next forecast being greatly discounted. Decisions facing a forecaster maybe exceedingly difficult to make. If, for example, as a flood is 

nearing its crest it threatens to overtop a levee or 

flood wall, a small difference in level may mean the 

difference between no flooding and disastrous flooding. 

HYDROLOGIC INVESTIGATIONS ATLASES 

The Geological Survey started its series of floodinformation atlases to provide information on flood 

hazards in easily read form. These atlases are published in the series entitled 11Hydrohgic Investigations Atlases. 11 The flood:-information atlases contain, 

briefly, a map showing the area inun1ated by one or 

more known floods, graphs showing frequency offlood 

discharges and flood stages at a gagirg: station in the 

area, a graph showing the height of annual floods 

above some specified elevation at a ga~ing station for 

the period of record, and profiles of one or more known. 

floods on one or more principal streams in the area. 

Some show cross-sections through th~ river channel 

and flood plains. The flood-frequency curves are generally for periods ranging from 25-50 years. Thetext 

on the map explains how depth of floocing at points in 

the area can be estimated. 

The primary purpose of the survey's flood-information atlas is to present historic a 1 d')cumentation of 

flooding by one or more floods that are known to have 

occurred. It must be emphasized, however, that the 

mere supplying of information as to where flood water 

has reached, and when, does not necessarily lead people 

to avoid flood danger. B u i I dings are constructed in 

fair weather when no flood hazard is evident. In the 

absence of clear and present danger, the typical citizen may not be easily persuaded by a map to protect 

himself from a danger that seems remote. The information can, however, be transformed into action by 

land-use planning. 

Flood damages begin with decisions to build on flood 

plains-often in disregard of the facts of flooding. 

Flood-damage abatement begins with definiton of the 

flood hazard, that is, presenting information on flooding 

of specific areas. Figure 2 is an exam":lle of how such 

informat,ion can be presented on a map. I 

Because the flood boundaries shewn on the floodinundation map are for a known flooc. the fact must 

be recognized that the flood might be exceeded at 

some time in the future. Sufficient data are shown to 

enable the user to determine, at a gaging station, the 

probable frequency of the flood that is mapped, unless 

the flood was of such magnitude that it is beyond the 

range through which frequency has been established by 

existing data. But the recurrence inter·.ral determined 

at a gaging station does not necessar~ly apply to the 
Figure 2.- Part of a flood - inundation map, showing how the flooded area is delineated. 

5 
flood level at all points on the map. For example, if 

the data indicated a 50-year recurrence interval at a 

gaging station on the main stream, that recurrence 

interval would not necessarily apply to the main stream 

above an upstream tributary or below a downstream 

tributary, or to the tributary itself. However, as the 

atlas presents a stage-frequency chart for the gaging 

station (or stations) and prof i 1 e s for one or more 

floods, a profile of the desired frequency can be drawn 

parallel to the nearest profile with reasonably reliable 

results. 

Flood-information atlases of the Geological Survey 

present hydrologic data concerning the extent, depth, 

and frequency of flooding that are essential for an 

appraisal of the hazards involved in occupancy and 

development of flood plains. They are intended to be a 

tool for individuals, governmental agencies, and others 

delegated with the responsibilities of solving existing 

flood problems and of formulating effective floodplain regulations that would minimize the creation of 

new flood problems. The maps are useful for, but not 

limited to, preparing building and zoning regulations, 

locating waste aisposal facilities, purchasing open 

space, developing recreational areas, and managing 

surface water in relation to the ground-water 

resources. Examples of the use of flood-hazard in formarion are: 

Flood-plain regulations: Establishment of reasonable controls over development of flood plains by 

local, regional, or State authorities requires information outlining the extent and degree of flood problems. 

Controls must be based on sound, impartial definition 

of the facts if they are to stand up in court as reasonable and fair. 

Mortgage underwriting: Efforts by bankers or private lenders to consider flood hazard in writing 

mortgages usually falter because of the lack of proper 

information. The availability of loans usually controls 

construction. 

Flood insurance: In order that premium rates may 

reflect the actual degree of risk, it is necessary to 

have accurate information concerning area, frequency, 

and depth of inundation. 

Flood warning: Local authorities, civil defense 

workers, corporations, and individuals require precise 

advance information if they are to benefit from flood 

warnings. When, for example, there is a forecast that 

a flood will crest at 18 feet, it must be known precisely 

which homes, factories, and other structures may be 

affected. 

Some examples of the uses of these flood atlases 

in northeastern Illinois, where 31 have already been 

completed, are: The communities of Highland Park, 

Wheeling, Harvey, Northfield, and Rolling Meadows 

have established zoning for residential buildings on 

basis of atlases. The Du Page County Forest Preserve, 

the Cook County Forest Preserve, and the Park District of High 1 and Park have used the atlases in 

acquiring land subject to flooding in order to prevent 

encroachments on the flood plains that would result in 

property damages. Real estate appraisers for the 

Chicago office of the Veterans Administration have to 

refer to any available atlas to determine possible flood 

potential of property on which VA loans have been 

applied for. After some recent flooding in south Cook 

County, the Northeastern Illinois Planning Commission 

was requested by the County Board president to prepare a flood-control plan for an area in the Harvey 

quadrangle; the hydrologic atlas for the Harvey quadrangle which had previously been prepared (Allen and 

May, 1964) was used as a basis·for the commission's 

plan. Scheaffer ( 1964) estimated that the flood mapping 

in northeastern Illinois had a benefit -cost !"atio of 40:1. 

Twelve atlases have been completed to date (August 

1966) for communities in Ohio. These atlases have 

been used for such purposes as highway design, floodinsurance studies, and approval by FHA of proposed 

housing developments. 

BASIC DATA ON FLOODS 

The Geological Survey began to compile streamflow 

records from a few gaging stations before 1890. The 

number of gaging stations increased steadily, and now 

more than 8,000 gaging stations are operated continuously in the conterminous United States and 225 in 

Alaska and Hawaii. Flood information is also available 

at an additional 7,000 stations or more that have been 

operated for periods of various lengths. 

The earliest published records consisted mainly of 

monthly discharges, daily gage heights, and rating 

tables whereby the user of the records could compute 

daily discharge if he wished to. After a few years the 

publication of daily discharge was started, and beginning with the 1914 streamflow reports annual extremes 

of discharge were added. FigurE;! 3 is a map of the 48 

conterminous States showing areas covered by the 

parts of the yearly reports on surface water supply of 

the United States. Since 1951, Parts 1, 2, 3, and 6 have 

been divided into subparts A and B. Part numbers have 

not been assigned to Alaska and Hawaii, for which 

similar reports also are published. 

As a supplement to the annual streamflow reports, 

descriptions of major floods have been reported in 

nearly 100 water-supply papers. Floodreportscontain 

detailed information on stages and discharges not 

presented in the annual streamflow reports, in addition 

to descriptive material and other pertinent data. 

Regional flood-frequency reports are being prepared 

in a series of 19 water-supply papers, 1671-1689 

inclusive, that will cover the conterminous United 

States. Each volume will be for a part, or subpart, as 

now used for publishing streamflow records. As of 

August 1966, 12 have been published-Parts 1-A, 2-A, 

6 
Figure 3.-Division of the 48 conterminous States into parts and subparts. 

3-A, 3-B, 4, 7, 8, 9, 10, 12, 13, and 14-and those for 

Parts 2-B, 6-A, and 11 are in process of publication. 

These reports are titled "Magnitude and frequency of 

floods in the United States," with an areal designation, 

for example, "Part 7, Lower Mississippi River basin." 

The public is, however, usually more interested in 

extent, depth, and probable frequency of flooding than 

in discharge rates. Hence, flood-inundation maps are 

one of the most satisfactory and useful ways of 

presenting flood information for urban areas to the 

public. 

The earliest flood-inundation maps were those that 

appeared in flood reports. The first Geological Survey 

flood report was Water-Supply Paper 88 by G. B. 

Hollister and M. 0. Leighton (1903) describing the 

flood of 1902 on the Passaic River in New Jersey; 

this paper contained such a map. Many subsequent 

flood reports have contained maps showing areas 

inundated by the subject flood. 

In 1959 the Geological Survey started a new series of 

flood-inundation maps published as hydrologic atlases, 

the first of which was Hydrologic Investigations Atlas 

HA-14, "Floods at Topeka, Kansas." Thetempoofthis 

program is accelerating in response to wide demand. 

As of November 1966, 63 atlases in 13 States and 

7 

Puerto Rico have been published and others are in 

preparation. The greatest concentration of atlases is 

in the environs of Chicago, where the Geological Survey is preparing a series of atlases in cooperation 

with the Northeastern Illinois Metropolitan Area Planning Commission. Twelve atlases have been prepared 

for communities in Ohio. 

A manual for the guidance of those engaged in floodplain planning, titled "Hydraulic and Hydrologic Aspects of Flood-Plain Planning," by Sulo W. Wiitala, 

Karl R. Jetter, and Alan J. Sommerville, was prepared 

by the G eo 1 o g i c a 1 Survey in cooperation with the 

Commonwealth of Pennsylvania and publishe1 in 1961 

as Water-Supply Paper 1526. It is a study of Chartiers 

Creek at Carnegie, Pa. The manual gives much the 

same type of information as the flood-inundation maps, 

but is much more comprehensive and describes the 

techniques used in considerable detail. 

OTHER PROGRAMS RELATED TO FLOOD-PLAIN 

PLANNING 

The Corps of Engineers and the Tennessee Valley 

Authority also collect and disseminate data of immediate application to flood-plain plannin~. Their 

programs are described briefly on the next rage. 
CORPS OF ENGINEERS 

Section 206, Public Law 86-645 (Flood Control Act 

of 1960) provides in part "That, in recognition of the 

increasing use and development of the flood plains of 

the rivers of the United States and of the need for information on flood hazards to serve as a guide to such 

development, and as a basis for avoiding future flood 

hazards by regulation of use by States and municipalities, the Secretary of the Army, through the Chief of 

Engineers, Department of the Army, is hereby 

authorized to compile and disseminate information on 

floods and flood damages, including identification of 

areas subject to inundation by floods of various magnitudes and frequencies, and general criteria for guidance in the use of flood plain areas; and to provide 

engineering advice to local interests for their use in 

planning to ameliorate the flood hazard." 

The major objectives under section 206 are: 

A. To compile in a useful form and disseminate to 

State and local governmental agencies, information on floods and potential flood hazarc;ls, 

including identification of areas subject to 

inundation by floods of various magnitudes and 

frequencies. 

B. To encourage optimum use of the Nation's 

river valleys by providing to State and local 

governmental agencies a factual basis for 

( 1) reducing future flood damages and hazards 

through carefully considered and well-planned 

local regulation and use of the flood plains, 

(2) planning such advance protection as may be 

economically justified for prospective land 

uses that could not be undertaken without protection, and (3) preserving adequate floodw:ay 

and channel rights-of-way and channel clearances. 

C. To provide publicly available information for 

the guidance of private citizens and interests 

on use of the flood plains. 

D. To reduce future expenditures for Federal 

projects to protect developments which, in 

the absence of the program, would have taken 

place, or for alleviation of flood problems 

arising from improper flood-plain development. 

TENNESSEE VALLEY AUTHORITY 

When the Tennessee Valley Authority was created by 

the Congress in 1933, it was assigned the control of 

floods in the Tennessee River basin as one of its primary objectives. Under this act TV A has built a system 

of multipurpose reservoirs, about one-fourth the cost of 

which has been allocated to flood control. Since the 

early 1950's TVA has been cooperating with the 

State of Tennessee and the other six Tennessee Valley 

States and many local communities in a flood-damage 

prevention program. As the major part of its contribution to this program, TV A has prepared reports 

outlining the b a s i c flood p r o b 1 e m s of local communities. Additional technical assistan~e and guidance 

is also available to the States and communities. The 

TVA reports do not, however, suggest solutions; 

solutions to the flood problems are left to the communities. 

By letter dated March 9, 1959, the Board of Directors 

of the Tennessee Valley Authority su':lmitted to the 

Congress a report entitled "A Progran for Reducing 

the National Flood Damage Potential.,. The proposed 

program contains three major points: 

A. An expanded program for collection, analysis, 

and wider use of flooq data. 

B. A broad approach to flood darr:age abatement 

which includes preventive as well as corrective 

measures. 

C. More active participation by State and local 

governments in solving flood problems. 

ZONING BY LOCAL GOVERI'1MENTS 

By John E. McCall 

Flood-plain studies are made to assist local communities in delineating or recommerding zones to 

which specific regulations should be applied. 

Difficult problems and a series of technical decisions 

are thus left to the State and local official. Frequently 

these officials and their staffs have nc closely comparable experience to guide them in the hydrologic 

engineering and legal phases of flood zoning. Nevertheless, positive actions must be take1 by the local 

officials if the potential benefits of flood-plain studies 

are to be fully realized. Fortunately, steadily growing 

numbers of engineers, lawyers, planners, and economists are becoming qualified to advise local government officials on the specific steps needed to institute flood-plain· zoning. Likewise, a considerable 

body of precedents is slowly building up in many States 

that furnish a model for others to follow. 

lt is not possible or practical to ou<:line herein a 

specific course of action by local officials because 

State laws on property rights and "police powers" for 

zoning are quite variable and local oriinances even 

more so. Likewise, some but not all States have 

encroachment statutes that regulate b•.tilding in the 

river channel or floodway, the provisions ofwhichare 

far from uniform across the country. Perhaps even 

more importantly, differing local conditions of 

flooding, relative values of flood-plain lands, and 

attitudes of the citizens of the community prohibit any 

standard solution. However, one or more of the following suggestions may prove helpful in putting into 

use the results of a flood-plain study. 

8 
1. Request the engineer or planning director of the 

municipality to contact officials of the State 

agency c on c e r n e d with flood c on t r o 1 and 

stream-channel encroachments. Usually this 

agency will also be coordinating the floodplain studies by the several Federal agencies 

to arrange priorities and to prevent duplication 

of effort. This State agency wi-ll likely be the 

best source of guidance on encroachment statutes, as well as specific State laws relating to 

flood zoning, and may be able to outline the 

steps to be taken and to furnish other staff 

assistance. Hopefully this agency can name 

other municipalities within the State which 

have already adopted flood-zoning codes or 

ordinances and may be able to suggest desirable modifications or alternatives based upon 

experience. 

2. ·consider retaining a firm of engineering or 

planning consultants with experience in the 

field of flood zoning. Such firms can develop 

the details quickly and for m u 1 ate a recommended ordinance, making full use of the 

information contained in the completed floodplain study. A consulting firm will be especially 

useful if the municipality has only a small 

technical staff or if that regular staff is fully 

committed on other work. 

3. Request the cooperation and assistance of a 

river-basin planning commission, a watershed 

association, or a regional-planning group, if 

any exist within the area. Frequently such 

organizations can furnish staff assistance and 

advice and may be especially helpful in sponsoring public meetings to gain public understanding and endorsement of flood zoning. 

4. Contact officials of State and Federalagencies 

concerned with urban redevelopment and acquisition of land for parks, recreation, and 

other open-space uses. FederalandStatefunds 

may be available to assist the municipality 

in obtaining development rights, easements, 

or fee title to flood-prone areas or long-range 

planning for conversion of land use on the flood 

plain. 

5. Refer to published reports listed in the references contained herein. A section on "Implementation of Flood-Plain Regulations" is 

given, for example, on pages 98-106 of the 

American Society of Civil Engineers Task 

Force report cited in the references. 

6. Invite representatives of the Federal agency 

that has prepared the flood-plain study and 

representatives of appropriate State, regional, 

or other Federal agencies to appear before 

the municipal officials, including the planning 

and zoning boards, to presentabriefsummary 

of the work accomplished and to discuss its 

9 

further implementation. Theserepresentatives may also be helpfulinpresentingbackground information at public rneetir~s, provided that their testimony be restricted to 

their sphere of knowledge andassignedagency 

functions. 

7. Recent development pertaining specifically to 

flood-plain management are Executive Order 

11296, signed by the President on August 10, 

1966, and House Document465, 89th Congress, 

2d session, transmitted by the President to the 

Speaker of the House of Representatives by 

letter dated August 10, 1966. The Executive 

Order directs Federal agencies to evaluate 

flood hazard in locating federally owned or 

financed buildings, roads, and other facilities, 

and in disposing of Federal lands and properties. The House Document is a rerort by a 

Task Force on Federal Flood Control Policy; 

it recommends specific action (1) to improve 

basic knowledge about flood hazard, (2) to 

coordinate and plan new developmerts on the 

flood plain, (3) to provide technical services 

to managers of flood-plain property, (4) to 

move toward a practical national pro-rram for 

flood insurance, and (5) to adjust Federal 

flood-control policy to sound criteria and 

changing needs. 

SELECTED REFERENCES 

Allen, Howard E., and May, V. Jeff, 1964, Floods in 

Harvey quadrangle, Illinois: U.S. Geol. Survey 

Hyd. Inv. Atlas HA-90. 

American Society of Civil Engineers, Task Force on 

Flood Plain Regulations, Flood Control Committee 

of the Hydraulics Division, 1962, Guide for the 

development of flood plain regulations, progress 

report: Jour. of the Hydraulics Div., Am. Soc. Civil 

Engineers, v. 88, no. HY5, Proc. Paper 3264, p. 73-

119. 

Burton, Ian, 1961, Education in the human us~ of flood 

plains: v. 60, no. 8, p. 362-371. 

Dalrymple, Tate, 1960, Flood-frequency analyses: U.S. 

Geol. Survey Water-Supply Paper 1543-A, 80 p. 

Goddard, James E., 1963, Flood plain management 

improves Man's environment: Jour. Waterways 

and Harbors Div., Am. Soc. Civil Engineers, v. 89, 

no. WW4, Proc. Paper 3702, Nov. 1963, p. 67-84. 

Hogan, Thomas M., 1963,_ State flood-plain zoning: 

Chicago, De Paul Law Rev., v. 12, no. 2, p. 246-

262. 

Hoyt, William G., and Langbein, Walter B., 1955, 

Floods: Princeton, Princeton Univ. Prees, 469 p. 
Kates, Robert W., 1962, Hazard and choiceperception 

in flood plain management: Chicago, Chicago Univ. 

Dept. Geog. Research Paper 78, 157 p. 

Leopold, Luna B., and Maddock, Thomas Jr., 1954, 

The flood control controversy: New York, The 

Ronald Press Co., 278 p. 

Mitchell, W. D., 1954, Floods in Illinois, magnitude 

and frequency: Illinois Dept. Public Works and 

Bldgs., Div. Waterways, 386 p. 

Murphy, Francis C., 1958, Regulating flood plain 

development: Chicago, Chicago Univ. Dept. Geog. 

Research Paper 56, 204 p. 

Sheaffer, John R., 1960, Flood proofing: Chicago, 

Chicago Univ. Dept. Geog. Research Paper 65, 

190 p. 

1964, The use of flood maps in northeastern 

---ui'inois: Highway Research Board of the National 

Academy of Sciences, National Research Council, 

Highway Research Record no. 58, p. 44-46. 

U.S. Congress, 1966, A unified National program for 

managing flood losses: House Doc. 465, 89th Cong., 

2d sess., 47 p. 

U.S. Senate, Select Committee on Water Resources, 

1960, Floods and flood control: Committee Prilnt 

15, 86th Cong., 2d sess., 77 p. 

Weber, Eugene W., and Sutton, Walter G., 1965, 

Environmental effects of flood plain regulation: 

Jour. Hydraulics Div., V. 91, no. HY4, Proc. Paper 

4402, p. 59-70. 

White, Gilbert F., 1945, Human adjustment to floods: 

Chicago, Chicago Univ. Dept. Geog, 225 p. 

ed., 1961, Papers on flood prob1.ems: Chicago, 

----cFiicago Univ. Dept. Geog. Research Paper 70, 

221 p. 

1964 Choice of adjustment to f10ods: Chicago, 

----chicago Univ. Dept. Geog. Research Paper 93, 

150 p. 

White, Gilbert F., and others, 1958, Changes in urban 

occupance of flood plains in the United States: 

Chicago, Chicago Univ. Dept. Geog. PesearchPaper 

57, 235 p. 

Wise, William S., 1957, Experiences in establishing 

stream channel encroachment limits in Connecticut: Northeastern States Conf. on Streamflow and 

Flood Control Proc, Princeton, N. J., 47 p. 

Wood, Wilmer H., 1965, Federal floodhazardmapping 

in the United States: Chicago, Chicago Univ. Dept. 

Geog., Master's thesis, 34 p. 

10 

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