CECW-EH-Y

Engineer 

Pamphlet

1110-2-9

Department of the Army

U.S. Army Corps of Engineers

Washington, DC 20314-1000

EP 1110-2-9

31 July 1994

Engineering and Design

HYDROLOGIC ENGINEERING STUDIES

DESIGN

Distribution Restriction Statement

Approved for public release; distribution is 

unlimited.
EP 1110-2-9

31 Jul 94

Foreword

Hydrologic engineering is a critical element in planning and evaluating flood damage

reduction measures and actions. Successful study completion of the hydrologic analysis

requires management of time, money and human resources. The hydrologic engineering

study products must satisfy study team and project sponsor needs. It is important to plan the

technical work at the beginning of the study for effective and efficient implementation.

Development of a hydrologic engineering management plan for the study is a crucial first step

towards accomplishing these objectives. This document describes activities required to

design and prepare a hydrologic engineering management plan for a Corps water resources

investigation. It is intended that such plans be used as a basis for determining firm estimates

of hydrologic engineering study resources and as a technical guide throughout the conduct of

the study.

FOR THE COMMANDER:

WILLIAM D. BROWN

Colonel, Corps of Engineers

Chief of Staff
DEPARTMENT OF THE ARMY EP 1110-2-9

U.S. Army Corps of Engineers

CECW-EH-Y Washington, DC 20314-1000

Pamphlet

No. 1110-2-9 31 July 1994

Engineering and Design

HYDROLOGIC ENGINEERING STUDIES DESIGN

Table of Contents

Subject Paragraph Page

Chapter 1

Introduction

Purpose . . . . . . . . . . . . . . . . . . . . . . 1-1 1-1

Applicability . . . . . . . . . . . . . . . . . . . 1-2 1-1

References . . . . . . . . . . . . . . . . . . . . 1-3 1-1

Chapter 2

The Hydrologic Engineering

Management Plan

General . . . . . . . . . . . . . . . . . . . . . . . 2-1 2-1

Use . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2-1

Personnel Involved . . . . . . . . . . . . . . . 2-3 2-1

HEMP . . . . . . . . . . . . . . . . . . . . . . . 2-4 2-2

Chapter 3

Scoping the Investigation

General . . . . . . . . . . . . . . . . . . . . . . . 3-1 3-1

Study Objective . . . . . . . . . . . . . . . . . 3-2 3-1

Type of Study . . . . . . . . . . . . . . . . . . 3-3 3-1

Key Items to Evaluate . . . . . . . . . . . . 3-4 3-3

Major Hydrologic Engineering

Activities Required . . . . . . . . . . . . . 3-5 3-4

Primary Hydrologic Engineering

Investigation Products . . . . . . . . . . . 3-6 3-4

Chapter 4

Development of an Initial HEMP

General . . . . . . . . . . . . . . . . . . . . . . . 4-1 4-1

Field Inspection . . . . . . . . . . . . . . . . . 4-2 4-1

Coordination . . . . . . . . . . . . . . . . . . . 4-3 4-1

Subject Paragraph Page

Collecting Information . . . . . . . . . . . . 4-4 4-1

Basic Analysis Approaches . . . . . . . . . 4-5 4-1

Initial HEMP Preparation . . . . . . . . . . 4-6 4-3

Time and Schedule Estimates . . . . . . . 4-7 4-3

Funding Estimates . . . . . . . . . . . . . . . 4-8 4-3

Resource Evaluation/Negotiation . . . . . 4-9 4-3

Chapter 5

Development of a Detailed HEMP

General . . . . . . . . . . . . . . . . . . . . . . . 5-1 5-1

Document Contents . . . . . . . . . . . . . . 5-2 5-1

Activity Sequence . . . . . . . . . . . . . . . 5-3 5-1

Hydrologic Study Management . . . . . . 5-4 5-1

Study Documentation and

Reporting . . . . . . . . . . . . . . . . . . . . 5-5 5-1

Appendix A

References . . . . . . . . . . . . . . . . . . A-1

Appendix B

List of Acronyms . . . . . . . . . . . . . B-1

Appendix C

Initial Hydrologic Engineering

Management Plan (HEMP) for a

Flood Damage Reduction Feasibility

Study . . . . . . . . . . . . . . . . . . . . . . C-1

i
EP 1110-2-9

31 Jul 94

Subject Paragraph Page

Appendix D

Generic Detailed Hydrologic

Engineering Management Plan

(HEMP) for a Flood Damage

Reduction Study . . . . . . . . . . . . . . D-1

Appendix E

Generic Detailed Hydrologic

Engineering Management Plan

(HEMP) for a Water Control

Management Study . . . . . . . . . . . . E-1

Subject Paragraph Page

Appendix F

Generic Detailed Hydrologic

Engineering Management Plan

(HEMP) for a Water Supply

Investigation . . . . . . . . . . . . . . . . . F-1

ii
DEPARTMENT OF THE ARMY EP 1110-2-9

U.S. Army Corps of Engineers

CECW-EH-Y Washington, DC 20314-1000

Pamphlet

No. 1110-2-9 31 July 1994

Engineering and Design

HYDROLOGIC ENGINEERING STUDIES DESIGN

Chapter 1

Introduction

1-1. Purpose

a. Current planning and management guidance for

civil works studies requires careful technical activity

management. Hydrologic engineering is a critical item,

especially for feasibility investigations.

b. Successful study completion requires management

of time, money, and human resources to accomplish the

necessary technical studies in an effective manner.

Hydrologic engineering study products must satisfy study

team and project sponsor needs. The technical studies

must also be completed within available financial

resources. It is important to plan the technical work at

the beginning of the study to accomplish these requirements. Development of a hydrologic engineering management plan (HEMP) for the study is a crucial first step

towards accomplishing these objectives. This document

describes activities necessary to design and prepare a

HEMP for a Corps water resource investigation.

1-2. Applicability

a. This pamphlet is applicable to HQUSACE elements, major subordinate commands, districts,

laboratories, and separate field operating activities having

civil works responsibilities in the hydrology and hydraulics fields.

b. The term hydrologic engineering is used

throughout this engineer pamphlet (EP) to encompass

activities in hydrology, hydraulics, water control management, sediment analyses, water quality, or other waterrelated elements addressed in a Corps water resource

investigation. Similarly, the hydrologic engineering management plan includes all activities in these disciplines.

The HEMP is intended to include the terms “hydraulic

study work plan” and “sediment study work plan” used in

other engineering manuals and publications.

1-3. References

Appendix A lists references that should be reviewed for

various types of water resource investigations and reporting levels. A list of frequently used acronyms is provided

in Appendix B.

1-1
EP 1110-2-9

31 Jul 94

Chapter 2

The Hydrologic Engineering Management

Plan

2-1. General

The HEMP is a technical outline of the hydrologic engineering studies necessary to formulate a solution to a

water resource problem. A HEMP could be an initial or

detailed work outline. An initial HEMP is developed to

define key issues and activities sufficient to address study

time and cost. A detailed HEMP outlines significant

technical activities in sufficient detail for the responsible

engineer to perform the analysis.

2-2. Use

The use of a hydrologic engineering management plan is

threefold. It is the following:

a. Basis for firm time and cost estimates. Accurate

estimates cannot be obtained without taking sufficient

time to develop firm and justifiable estimates for the

feasibility or the preconstruction engineering and design

(PED) phase. The HEMP should reflect the hydrologic

information needs of the study team and define the

method of proceeding through the entire study process.

Agreement between hydrologic engineering, planning, and

project management on the study scope must be reached

for an accurate cost estimate. The HEMP should be

viewed as a contract to perform the stated work for the

agreed-upon amounts of funds and time. Written records

and daily or weekly logs of accomplishments are important to properly manage and track the study time and fund

expenditures throughout the study.

b. Technical guide for the hydrologic engineer.

Many feasibility-phase or PED investigations require two

or more years of hydrologic engineering effort. Even an

experienced hydrologic engineer cannot foresee all facets

of a multi-year study without significant planning and

input from others. A detailed technical outline allows

work to be performed effectively and efficiently, without

close supervision. The preparation and use of a HEMP

provides inexperienced hydrologic engineers with a

clearer understanding of the analysis procedures and

reporting process. A HEMP provides the basis for meaningful discussion and negotiation and helps in making

decisions on refinements and changes as the study

progresses.

c. Review contract. The HEMP provides the contract that will be used to guide the review of the hydrologic engineering final project.

2-3. Personnel Involved

The HEMP is a hydrologic engineering document usually

prepared by the principal engineer for the study. It is not

required or approved by other disciplines, but must incorporate information needs of all disciplines. The hydrologic engineer plays the most important role in its

development, but others have input as well. They

include:

a. Senior personnel--the HEMP may be prepared by

an experienced engineer or a section chief to ensure that

the time and cost estimates are adequate and that they

address all study issues. Supervisors should review and

critique the HEMP.

b. Project manager (PM)--discussions on the effect

of the HEMP to the overall project schedule, cost, budget,

and all other project processes should be held with the

PM that is responsible for the progress of the project.

c. Planning technical manager--discussions with the

planning technical manager on the alternatives to be

addressed, level of detail, combinations of different alternatives, study milestone dates, and other pertinent information should be held, agreed upon, and incorporated into

the HEMP.

d. Economist--the economist is important in establishing the type of analysis required. Significant agricultural damages require knowledge of the time of year

and duration of the flood and typically use a continuous

simulation analysis. A study area with primarily urban

damages could use an event analysis. Information on

damage reaches is necessary to estimate the location of

hydrologic computation points to give stage-frequency

information at designated damage centers. This type of

information is required to perform risk-based analysis for

project alternatives in close coordination with economists

and all other team members.

e. Local sponsor--the sponsor almost always has

useful hydrologic information on the study area. The

sponsor may also have definite views on the type and size

of flood damage alternatives most suitable for the

investigation.

2-1
EP 1110-2-9

31 Jul 94

f. Cost engineer--the cost engineer must have hydrologic engineering design information in sufficient detail to

prepare project costs.

g. Realty specialist--the real estate specialist needs

stage-frequency, area inundated, project location, and

other information to complete the analysis.

h. Other team members--structural, geotechnical,

mechanical engineers, regulatory personnel, the recreational planner, and environmental specialist usually need

specific information from the hydrologic engineer.

i. Review authority--controversial, complex, or costly

hydrologic analyses should be discussed with Division

and possibly HQUSACE hydrologic engineering personnel

to confirm the approach and procedures proposed. This

should be accomplished both informally and through the

mandatory technical review conferences. These disciplines should be contacted, as necessary, during the reconnaissance-phase study to ascertain their needs and views

on hydrologic information required for the feasibilityphase investigation.

2-4. HEMP

The HEMP should outline feasibility study hydrologic

engineering activities to be included in the initial project

management plan (IPMP), or the detailed project design

needed in the project management plan (PMP). The

HEMP should be prepared at the end of the reconnaissance study so that time and funds needed may be firmly

estimated during the feasibility-phase study. It becomes

part of the IPMP forming the basis for the Feasibility

Cost-Shared Agreement (FCSA). Similarly, a HEMP is

prepared at the end of the feasibility-phase study to establish hydrologic engineering time and costs necessary for

PED. HEMPs are prepared during the feasibility phase,

to detail all hydrologic engineering work necessary during

feasibility, and during the PED phase for the balance of

the hydrologic engineering effort. It is assumed throughout this document that both HEMPs will be prepared,

but this does not mean that both are always required. In

fact, if a detailed hydrologic engineering management

plan can be developed at the end of the reconnaissance

phase, it should be done. A sequence for developing

hydrologic engineering management plans is shown in

Figure 1.

Figure 1. Sequence of hydrologic planning activities for Civil Works studies

Receive reconnaissance-phase study funding

Complete reconnaissance-phase study, with an economically justified

solution found

Prepare HEMP for inclusion in IPMP

Submit reconnaissance-phase report

Receive feasibility-phase funding

Complete feasibility-phase study, with NED plan selected

Prepare HEMP for inclusion in PMP of PED-phase study;

submit feasibility-phase study

Receive PED-phase study funding

Complete PED (design memorandum (DM), plans, and specs)

Construction

2-2
EP 1110-2-9

31 Jul 94

Chapter 3

Scoping the Investigation

3-1. General

A preliminary assessment should be made to gain an

understanding of the key issues and concerns to be

addressed in the analysis. This assessment leads to an

initial hydrologic engineering management plan, based on

the main considerations of the study.

3-2. Study Objective

The major study objectives should be defined; flood damage reduction, navigation, water supply, environmental

restoration, water control, hydropower, etc. Geographic

scope of the study should be determined and key locations

requiring hydrologic information specified. Preliminary

hydrologic engineering requirements and strategies to

accomplish these objectives may be postulated.

3-3. Type of Study

The type of study requires different levels of hydrologic

planning, ranging from very little to extensive. The various studies for which a HEMP may be developed are

described in the following paragraphs, with reconnaissance, feasibility, and preconstruction engineering and

design comprising the usual path for most Corps studies.

a. Reconnaissance-phase study.

(1) Initial HEMP. An initial HEMP should be prepared to provide a cost estimate for the reconnaissance

phase, which is 100 percent Federally funded. However,

reconnaissance funds are usually obtained in advance of

hydrologic engineering planning, as this phase emphasizes

the use of existing studies and data to perform the hydrologic analysis. For this situation, a HEMP may be prepared and used as an internal document. If time and

funding permit, establishing the without-project hydrology

and hydraulics for the existing condition of the watershed

is desirable.

(2) IPMP. An IPMP is the end result of a successful

reconnaissance-phase study, which must include adequate

technical hydrologic engineering information to successfully complete a feasibility cost-sharing agreement

(FCSA) with the sponsor. The hydrologic engineering

management plan must identify the major technical activities and establish time and cost estimates. The estimates

are used in the initial project management plan to develop

funding and scheduling required for the feasibility-phase

investigation. An initial HEMP would normally be prepared at the end of the reconnaissance phase. Any complex or unusual technical hydrologic issues should be

discussed at the technical review conference (TRC)

required at the end of reconnaissance and included in the

plan. An example of an initial hydrologic engineering

management plan for a local protection project is shown

in Appendix C.

b. Feasibility-phase study.

(1) Detailed HEMP. As soon as feasibility funding

is received, the initial HEMP of the reconnaissance phase

may be expanded to detail the hydrologic engineering

activities for week-to-week use by the hydrologic engineer

throughout the study. Technical studies are detailed so

that work activity durations may be established, milestone

dates set, etc. Examples of detailed HEMP’s are shown

in Appendices D, E, and F. This phase results in a feasibility report with a series of engineering appendices. The

appendices are in sufficient detail to allow the work effort

to generally proceed directly to the design memorandum

phase.

(2) Project management plan. A project management plan is prepared at the end of the feasibility-phase

study, assuming an economically justified project is recommended and a cost-sharing partner exists. It requires

sufficient hydrologic engineering detail to scope, cost, and

schedule the activities for the balance of preconstruction

engineering and design. The PMP forms the basis for the

project cooperation agreement (PCA) with the sponsor, to

complete the detailed design and construct the project.

The major hydrologic engineering activities for PED must

be identified and cost estimates made for the project management plan. Figure 1 illustrates this phase.

c. Preconstruction engineering and design. The

PED phase concentrates on the detailed design of the

project. It would normally be expected to consist of one

or more design documents and plans and specifications to

construct the project.

(1) Design memoranda. The project should move

directly from the feasibility phase to PED, with a design

memorandum (DM) to establish the detailed technical

design necessary to construct the project. Consequently, a

detailed HEMP would be prepared at the start of PED to

outline the balance of the technical hydrologic engineering

effort. This detailed HEMP would build on the initial

hydrologic engineering management plan prepared for the

PMP. PED hydrologic activities often include physical

3-1
EP 1110-2-9

31 Jul 94

model testing, detailed hydraulic design, quantitative

sediment transport analysis, two-dimensional flow analyse,

etc., which provide the technical detail for final design of

the project.

(2) Plans and specifications. The detailed HEMP

prepared at the start of PED should include the hydrologic

activities necessary for this phase of the project. Hydrologic engineering effort in the plans and specifications

phase typically incorporates results of physical model tests

into the hydraulic design, preparation of stage hydrographs to show potential high-water periods affecting

construction, minor modifications in the hydraulic design

based on the additional detailed topographic and soils data

obtained, and any changes found in the site conditions.

d. Continuing authority. These studies are typically

performed as a two-phase process: a reconnaissance

report performed at Federal expense, followed by a costshared detailed project report.

(1) Reconnaissance. The reconnaissance phase of a

continuing authority study is similar to a feasibility investigation. It is performed at 100-percent Federal expense

under the continuing authorities program. A HEMP is

prepared for the reconnaissance phase after receipt of

funding. The HEMP would be similar to that of paragraph 3-3a to establish funding requirements for the

reconnaissance-phase study.

(2) Detailed project report. The detailed project

report (DPR) is equivalent to a feature design memorandum; therefore, a hydrologic engineering management

plan similar to that needed for the PMP would be prepared at the end of the reconnaissance report, with a

detailed HEMP formulated after receipt of detailed project

report funding. The hydrologic engineering management

sequence for continuing authority studies is illustrated in

Figure 2.

e. Regulatory. An assessment of the impact of a

proposal is necessary to obtain a permit for project construction in the floodplain. The hydrologic information

needed to submit the permit for Corps projects should be

readily available from previous work. A hydrologic engineering management plan for regulatory purposes should

seldom be necessary.

f. Water control. Establishing a water control plan

for a new project or updating an existing plan for new or

changed purposes represents a major hydrologic engineering effort. The plan is described in a water control

manual. Funding is usually from the operation and maintenance (O&M) program for an existing project. General

investigations funding (reconnaissance and feasibility) is

appropriate for analyzing the addition of new project

purposes to an existing project. A HEMP is necessary to

establish time and cost estimates for O&M funding. A

detailed hydrologic engineering management plan is prepared for technical activities after receipt of funding.

Hydrologic engineering funding for water control activities for a new project should be included with the HEMP

for the PED-phase work effort.

g. Water supply. These investigations normally concentrate on potential reservoir storage reallocation for

Figure 2. Sequence of hydrologic planning activities for continuing authority studies

Initial funding

Prepare HEMP for reconnaissance study

Receive funding for reconnaissance-phase study

Complete reconnaissance report, with an economically justified

project resulting

Prepare HEMP for detailed project report study

Receive detailed project report funding

Complete detailed project report

Prepare plans and specs, construct project

3-2
EP 1110-2-9

31 Jul 94

water supply or for drought operation planning. A twophase planning process (reconnaissance and feasibility)

would be followed for reservoir reallocation studies, with

the HEMP requirements similar to those described in

paragraphs 2-3a and b. Drought operation planning is

usually done for an existing project with O&M funding.

A HEMP would be necessary for accurate estimates.

3-4. Key Items to Evaluate

a. Major issues. The HEMP must outline the information and methods necessary to address the major issues

of the hydrologic engineering study. Methods and procedures needed to address complex or precedent-setting

problems, sensitive environmental concerns, use of outside

consultants (including Corps labs), local sponsor requirements, the need for new physical or analytical model

development, adverse effects caused by a potential project, etc., would be scoped for budgeting purposes.

b. Level of detail. Although the study phase will

usually establish the overall level of detail, the interdisciplinary planning team must be queried to obtain their

ideas on the hydrologic information they need. However,

the hydrologic engineering effort often plays the largest

role in determining the level of detail. Depending on the

appropriate study costs, several iterations between the

hydrologic engineer and the study team may be necessary

to establish a level of detail commensurate with the level

of study funding. The development of a detailed plan,

prepared at the start of the study, should result in a more

efficient and effective progression of the study. Adequate

planning at the start of the study may result in lower

overall hydrologic engineering costs.

c. Hydrologic information availability and requirements. Databases would be examined to determine the

rainfall, streamflow, topographic, and other records available for the particular study. The need for establishing a

limited data collection program to address the objectives

of the study would be determined. Existing Federal and

non-Federal projects (reservoirs, levees, water withdrawals, etc.) affecting the analysis would be determined.

d. Unusual features.

(1) Items requiring additional engineering effort.

Items peculiar to the study area that require additional

hydrologic engineering effort must be addressed, especially if the work is necessary in the feasibility

investigation.

(a) Flat slopes and wide floodplains could require a

one- or two-dimensional unsteady flow analysis, resulting

in significant higher study costs compared to using simpler models.

(b) Major quantitative sedimentation investigations

may be necessary to firmly establish project feasibility.

Reservoirs and extensive channel modifications may

require significant quantitative sediment investigations

during the feasibility phase.

(c) Physical model testing may be required during

feasibility to ensure the workability of a project, such as

locating a replacement lock away from the main navigation channel or designing a super-critical flow channel for

a highly populated area.

(d) Lake stage-frequency analysis in closed basins,

that do not drain to a downstream watershed.

(e) Major groundwater, snow hydrology, water

quality, or other investigations.

(f) Complex reservoir system problems in which

political or environmental issues mandate extensive and

unusual systems modeling.

(g) Unstable rating relationships, complex interior

flood control studies, multi-reservoir analyses, and other

difficult water resource analyses must be recognized and

evaluated during the early planning process leading to a

HEMP.

(2) Peer review. Studies having unusual features

and complex analyses may benefit from peer review.

HQUSACE has established a peer review procedure

through the HQUSACE-sponsored Hydrology Committee,

with membership consisting of selected senior hydraulic

engineers from Districts and Divisions. The Hydrology

Committee will meet with District personnel to review the

study/project and offer suggestions on the District’s plan

of analysis. The District incurs no cost for committee

participation. Separate committees on Channel Stabilization, Tidal Hydraulics, and Water Quality are also available for assistance on unusual features in these areas.

ER 15-2-14 further describes these four committees.

e. Study boundaries. The HEMP must distinguish

between study boundaries and project boundaries in the

development of estimates. Project effects often extend far

upstream and downstream on the main stem of the study

3-3
EP 1110-2-9

31 Jul 94

stream, as well as up tributaries. Proposed projects may

change the flood hydrology and sediment regime throughout the watershed, not just near the proposed project.

Changes in water control management practices at Corps

reservoirs can also affect interests remote from the reservoir site. The hydrologic analysis must include the evaluation of all positive and negative effects of a potential

project or water control management change throughout

the stream system or study area.

f. Likely alternatives. The screening process used

in the reconnaissance phase should result in a reduced

number of alternatives to evaluate in detail for determination of the national economic development (NED) plan

during the feasibility phase. The HEMP will include the

most practical alternative(s) or combinations of alternatives to estimate the cost of the hydrologic engineering

work effort. The major with-project scenarios must be

developed by the study team for both preliminary and

final scoping of the technical activities. The no-action

case must also be determined for comparison to the withproject alternatives. Similarly, agreement should be

reached among study team members, during the HEMP

preparation, concerning the number of iterations (or sizes)

to be evaluated for each alternative. Three or four sizes

for each of two or three alternatives should be adequate

for most studies.

3-5. Major Hydrologic Engineering Activities

Required

The Corps typically assesses with- and without-alternative

conditions for the main study objective(s).

a. Flood damage reduction. The HEMP should

describe or reference the major study components: watershed hydrology, river hydraulics, frequency analysis,

sedimentation analysis, storage operation, hydraulic

design, etc., for both the with and without alternative

condition. Analysis will often involve discrete events,

either actual or, more typically, hypothetical, and will

include development of uncertainty relationships for riskbased analysis. ER 1105-2-100 contains additional information in this area.

b. Water control management. The HEMP should

describe or reference the major study components: flood

control capabilities, storage allocated for various project

purposes, drought augmentation, operational analyses, data

systems, forecasting, etc., for the existing and proposed

method of regulation. Analyses usually involve discrete

events and continuous record techniques. ER 1110-2-240

and EM 1110-2-3600 contain additional information in

this area.

c. Water supply investigations. The HEMP should

describe or reference the major study components: existing project purposes and storage allocations of each,

upstream and downstream demands, supply analysis,

hydraulic data (uniform database), drought frequency

analysis (volumes and durations), distribution system

(pumping, conveyance, and storage), etc., for the existing

and proposed reallocation of reservoir storage. Analysis

may be for one or more severe droughts, although the full

period of record can be used, similar to water control

management methods. ER 1110-2-241 and ER 1110-2-

1941 contain additional information.

3-6. Primary Hydrologic Engineering Investigation Products

The hydrologic engineering results needed by the study

team may include the following information, as discussed

by general study type:

a. Flood damage reduction. The main product will

be the damage reduction effects of the selected alternative

on the floods in the watershed. Supplemental investigation products could include: discharge-frequency relationships, flood elevations, and areas inundated with and

without a specified structural alternative (reservoir, channel, levee, diversion, pumping plant), stage-duration

relationships, sizes of various alternatives for costing

purposes, sedimentation analyses, residual flooding, flood

forecasting and warning system, etc. Nonstructural alternatives may require only the without-project condition,

since these alternatives affect the stage-damage relationship only and result in little, if any, change in hydrologic

or hydraulic relationships.

b. Water control management. The main product

will be a new or revised set of procedures for project

operation and hydrologic forecasting, contained in a water

control manual. A range of flows should be addressed,

from the inflow design flood to the record drought.

Effects on the watershed sediment regime could be a

required product. Supplemental investigation products

could include: operation procedures, stage-duration and

frequency, discharge-frequency, emergency operation

procedures, gage data network, computer equipment

needed, conservation and/or hydropower procedures, flood

warning and preparedness procedures, and other required

information.

3-4
EP 1110-2-9

31 Jul 94

c. Water supply investigations. The main product

will be a reservoir storage reallocation to satisfy changed

demands, such as decreased hydropower storage for

increased water supply storage, or to satisfy as many

critical demands as possible during time of drought.

Water supply studies are usually performed for storage

reallocations of existing reservoirs or for drought contingency planning for existing Federal reservoirs. Drought

contingency planning analysis is a separate study, but is

usually included as an appendix to a reservoir water control manual. Supplemental investigation products could

include both seasonal and annual: current and modified

condition discharge-frequency, reservoir storagefrequency, pool elevation-duration, flow- or storageduration relationships, and power generation values.

3-5
EP 1110-2-9

31 Jul 94

Chapter 4

Development of an Initial HEMP

4-1. General

A typical strategy would first include a preliminary

assessment identifying the problems and issues described

in both this chapter and in Chapter 3. This assessment

would result in the preparation of an initial hydrologic

engineering management plan, sufficient to scope time

and funding requirements. The initial HEMP would

include appropriate contingencies to establish total hydrologic engineering cost for inclusion in the initial project

management plan or in the PMP. If time and funds are

available at the end of the reconnaissance phase, a

detailed HEMP could be prepared in lieu of the initial

plan. A senior hydrologic engineer could develop the

initial hydrologic engineering management plan, while the

responsible engineer could expand this document into a

detailed HEMP. The activities in Chapters 3, 4, and 5 are

summarized in Figure 3.

4-2. Field Inspection

An early field inspection is necessary to become familiar

with site-specific problems that must be incorporated in

the HEMP. A continuous field presence should be maintained throughout the study to keep pace with changes to

the study area. Field inspection would focus on any

features causing analysis problems, ongoing changes in

the study area, interviews with locals concerning past

flood experiences or changes to the area since large past

floods, contacting local agencies to obtain information on

the area and on any plans for modifications that could

affect the Corps analysis, and other items of interest.

4-3. Coordination

Various coordination and information needs must be

addressed in the HEMP.

a. Study team needs. The various hydrologic information needs of the interdisciplinary planning team have

been briefly described in Chapter 2, paragraph 2-3.

Anticipated hydrologic information needs should be

obtained from the study team during the reconnaissance

process for inclusion in time and cost estimates and schedule for the feasibility phase.

b. Sponsor needs.

(1) The sponsor usually has valuable information

about the study area. The sponsor may have some capability for obtaining necessary information pertinent to the

project or for performing some of the hydrologic engineering necessary for the study, which could be a credit

to the sponsor. The cost-sharing partner normally has

specific views on the type of alternatives believed most

suitable for the study area. All of these possibilities

would be reflected in the HEMP.

(2) An initial HEMP is useful in dealing with the

local sponsor on necessary hydrologic engineering activities and in justifying the hydrologic engineering cost

estimate, which the sponsor must cost-share. Discussing

the necessary hydrologic activities, summarized in a

HEMP, with the sponsor is more likely to result in agreement on the effort involved than to simply present the

sponsor with a total cost.

c. Feasibility cost-sharing agreement. The FCSA

cannot be negotiated adequately without having the hydrologic engineering work defined in sufficient detail. The

hydrologic engineer must be involved in any negotiations

concerning hydrologic engineering, or in hydrologic engineering work that the sponsor might perform for the project. The hydrologic engineer must approve the technical

value of the sponsor’s work before it can be accepted as a

sponsor credit.

4-4. Collecting Information

The hydrologic engineer must evaluate the available data,

as well as estimate what additional data are necessary for

conducting the study. Actual climatologic, hydrologic,

hydraulic, sediment, water quality and infrastructure data

available would be determined, sources and quality of

such data evaluated, and any special needs for a limited

data collection program determined. Topographic information necessary to develop accurate water surface profile

information will be estimated.

4-5. Basic Analysis Approaches

The analysis approach must be based on the hydrologic

information needs of the study team, unusual features of

the study, the type of alternatives requiring investigation,

the significance of the alternatives on the sediment

4-1
EP 1110-2-9

31 Jul 94

Figure 3. Hydrologic study design

4-2
EP 1110-2-9

31 Jul 94

regime, and other considerations. Selection of the

appropriate hydrologic model, a single event or a continuous model, steady or unsteady flow procedures, and

qualitative or quantitative sediment analysis must depend

on the judgment and skills of the responsible hydrologic

engineer. Models and procedures should be selected

based on the reduction of uncertainty in the end product.

If a sophisticated model or procedure does not give a

significantly improved result and reduced uncertainty, a

less sophisticated method is probably appropriate. Selection of new models or procedures could include an allowance for assistance by the (HEC), the U.S. Army Engineer

Waterways Experiment Station (WES), or other consultants. New models and innovative, unusual procedures

should be approved by higher authority at the technical

review conference held at the end of the reconnaissance

phase, or earlier. Peer review by the appropriate

HQUSACE-sponsored committee should also be considered for unusual or complex analyses.

4-6. Initial HEMP Preparation

Using information from the preliminary assessment, identify the major activities, including alternatives to be analyzed and the range of sizes to study. The initial HEMP

would be used to estimate human resource requirements

for each activity to establish a total hydrologic engineering study cost. An example of an initial HEMP for a

flood control study is presented in Appendix C.

4-7. Time and Schedule Estimates

With the initial HEMP, determine the human resources

required for each major technical hydrologic engineering

study component (rainfall analyses, water surface profile,

channel modifications, etc.) and for the complete hydrologic engineering effort. Estimate the human resources

necessary for each discipline (hydrologic engineer, technician, supervisor, etc.). Estimate when necessary information must be furnished to (or received from) other study

team members. Clearly indicate the number of alternatives to be evaluated and the number of sizes to analyze

for each alternative. Determine if special training is necessary for the responsible engineer to effectively perform

the study. Include any other factors having a significant

impact on required time for the hydrologic engineering

analysis, along with any assumptions on which the estimate is based. Include a reasonable contingency

allowance.

4-8. Funding Estimates

Determine the chargeable rate for each technical discipline

used in the hydrologic work. Include all direct and indirect overhead charges for the division to which hydrologic

engineering is assigned and for the District. At the time

of publication of this EP, the chargeable rate for District

personnel averaged about 2.8-3.0 times the base salary.

For example, if an engineer earned $25/hour base wages,

the project is charged $70-75/hour for each hour charged

by the staff member. Total the funds for each major

activity and for the total hydrologic engineering effort.

Forward the estimate to the planning technical manager

for approval of hydrologic time and costs.

4-9. Resource Evaluation/Negotiation

a. Through an iterative process, come to agreement

with all concerned on study objectives, analysis

approaches, alternatives to be analyzed, sizes to study, and

level of detail obtainable with funding constraints. Prepare written documentation on this agreement and include

any problems, difficulties, or lack of engineering detail

that may result from this reduced effort. Finalize these

activities in the HEMP for inclusion in the initial project

management plan, or PMP. Reference these changes and

agreements in the hydrologic engineering management

plan, or in separate documentation.

b. The IPMP is reviewed and approved by the chief

of each technical division. The signature of the Chief of

the Engineering Division (the division to which hydrologic engineering is normally assigned) on the IPMP indicates that the hydrologic engineer agrees to perform these

activities for the funding specified. The responsibility

then falls on the hydrologic engineer to ensure that the

actual time and costs are commensurate with the agreed

amount. Additional hydrologic work required by the

interdisciplinary planning study team or sponsor during

the feasibility or design phase must result in additional

resources being made available by the project or study

manager.

4-3
EP 1110-2-9

31 Jul 94

Chapter 5

Development of a Detailed HEMP

5.1. General

After receipt of funding for the feasibility or design

phase, the hydrologic engineer would build on the initial

hydrologic engineering management plan to develop the

fully detailed HEMP.

5-2. Document Contents

Using the results of Chapters 3 and 4, develop the

detailed HEMP commensurate with the level of reporting.

The detailed HEMP for the feasibility phase would document the step-by-step analysis of data development, storm

studies, routing operations, unit hydrograph development,

model calibration, etc., while the detailed HEMP for the

PED phase would document the hydraulic design, physical

model testing requirements, hydrologic studies needed for

water control manuals, detailed sediment investigations,

multi-dimensional modeling efforts, etc. Appendices D

through F give generic examples of different hydrologic

engineering management plans. The document should be

reviewed and approved by the immediate supervisor.

Complex analyses may benefit from a higher level review.

A courtesy copy should be provided to the study or project manager.

5-3. Activity Sequence

For scheduling purposes, assign durations to each work

item for all significant activities in the entire HEMP.

Establish milestone dates for each major component. Use

milestone dates for furnishing necessary information to

various members of the interdisciplinary planning team,

receiving information required from others to meet the

study completion date, and meeting any other scheduled

events.

5-4. Hydrologic Study Management

The detailed hydrologic engineering management plan

could be used on a day-to-day or week-to-week basis,

especially for relatively new hydraulic engineers. Periodic

updates and further detailing of tasks should be performed

as work progresses or as additional effort becomes necessary to meet new interdisciplinary planning team or local

sponsor requests. Additional work effort required by

others, that is not included in the HEMP, becomes the

basis for increases in hydrologic engineering time and

cost allocations. This situation again emphasizes the need

for a HEMP and for the responsible hydrologic engineer

to use it throughout the study.

5-5. Study Documentation and Reporting

Update the HEMP for final documentation of the completed technical study so that future, similar work will

have a better planning basis. Recording the actual human

resources expended for each major activity is particularly

useful for estimating future studies. Use the completed

hydrologic engineering management plan for the outline

of a technical hydrologic engineering appendix to the

study documentation.

5-1
EP 1110-2-9

31 Jul 94

Appendix A

References

A-1. Required Publications

ER 15-2-14

Committees on Tidal Hydraulics, Channel Stabilization,

Water Quality and Hydrology

ER 1105-2-100

Guidance for Conducting Civil Works Planning Studies

ER 1110-2-240

Water Control Management

ER 1110-2-241

Use of Storage Allocated for Flood Control and Navigation at Non-Corps Projects

ER 1110-2-1941

Drought Contingency Plans

EM 1110-2-1701

Hydropower

EM 1110-2-3600

Management of Water Control Systems

EM 1110-2-4000

Sedimentation Investigations of Rivers and Reservoirs

U.S. Army Corps of Engineers. 1992.

“Proceedings of a Seminar on Initial Project Management

Plans for Hydrologic Engineering and Economic Analysis,” SP-25, Hydrologic Engineering Center.

A-2. Related Publications

ER 5-7-1 (FR)

Project Management

ER 1110-2-1150

Engineering and Design for Civil Works Projects

ER 1110-2-1460

Hydrologic Engineering Management

EP 1165-2-1

Digest of Water Resources Policies

EM 1110-2-1413

Hydrologic Analysis of Interior Areas

Cochran 1965

Cochran, Albert L., Memorandum “A,” Hydrologic Engineering Associated with Survey Studies, January 1965.

Water Resources Council. 1982.

“Guidance for Determining Flood Flow Frequency,” Bulletin No. 17B, Geological Survey, U.S. Department of the

Interior.

A-1
EP 1110-2-9

31 Jul 94

Appendix B

List of Acronyms

CECW

Corp of Engineers, Civil Works (Washington, DC)

CECW-EH

Above plus Engineering Division, Hydrology and Hydraulics Branch

COOP

Continuity of Operations

DM

Design Memorandum

DPR

Detailed Project Report

EC

Engineer Circular

EM

Engineer Manual

EP

Engineer Pamphlet

ER

Engineer Regulation

ETL

Engineer Technical Letter

FCSA

Feasibility Cost Sharing Agreement

GDM

General Design Memorandum

HEC

Hydrologic Engineering Center

HEC-DSS

Hydrologic Engineering Center Data Storage System

(family of computer programs)

HEMP

Hydrologic Engineering Management Plan

HQUSACE

Headquarters, United States Army Corps of Engineers

IPMP

Initial Project Management Plan

LRR

Limited Reevaluation Report

M&I

Municipal and Industrial (water supply)

NED

National Economic Development (plan)

NWS

National Weather Service

O&M

Operation and Maintenance

OMRRR

Operation, Maintenance, Repairs, Replacement,

Rehabilitation

PCA

Project Cooperation Agreement

PED

Preconstruction Engineering and Design

PMP

Project Management Plan

PRM

Prescriptive Reservoir Model

SCS

Soil Conservation Service

SSARR

Streamflow Synthesis and Reservoir Regulation (model)

TRC

Technical Review Conference

USBR

United States Bureau of Reclamation

USGS

United States Geological Survey

B-1
EP 1110-2-9

31 Jul 94

WCDS

Water Control Data System

WES

U.S. Army Engineer Waterways Experiment Station

WRDA

Water Resource Development Act

B-2
EP 1110-2-9

31 Jul 94

Appendix C

Initial Hydrologic Engineering Management Plan (HEMP) for a Flood Damage

Reduction Feasibility Study

C-1. Scenario

a. The study objective is the development of a flood

protection plan for a community experiencing periodic

flooding from a stream draining a few hundred square

miles. The reconnaissance-phase study was based primarily on flood insurance study data and an abbreviated

hydrologic engineering analysis. The study has determined that a levee project is economically feasible. The

community is willing to be the cost-sharing local sponsor

and would like a minimum certifiable level of protection

of a 1 percent chance event. A gage with 15 years of discharge data is available at the site, with additional, shortrecord gages located elsewhere in the watershed.

b. The feasibility phase will establish existing and

future without-project conditions. After discussions with

the interdisciplinary study team and local sponsor, it was

decided that three heights of levee will be studied, along

with six combinations of levee height and channel

improvements to develop the economic optimum plan. A

total of nine alternatives will be evaluated. As all the

levee alternatives are along a similar alignment, a detailed

interior flood analysis will be evaluated for only the

National Economic Development Plan (NED) levee or

levee and channel plan. The hydrologic engineer must

prepare an initial Hydrologic Engineering Management

Plan (HEMP) for the hydrologic engineering cost estimate

for the feasibility phase.

c. This sample initial HEMP represents what one

might develop at the end of the reconnaissance-phase

study for a time and cost estimate for use in the initial

project management plan.

C-2. Preliminary Investigations/Initial Preparation

Finalize study objectives; confer with the study team

members on hydrologic engineering information requirements, study constraints, development information needs,

and field reconnaissance; prepare survey data request;

prepare detailed HEMP.

C-3. Development C-3. Development of Basin Model Hydrologic Hydrologic

Engineering Center Engineering Center (HEC-1) (HEC-1)

a. Calibration of runoff parameters. Using basin

gage data, develop unit hydrograph and loss rate parameters for use in the study.

b. Delineation of subareas. Subdivide study watershed based on the need for discharge-frequency information at specific locations: major tributaries, damage index

points, routing reaches, project sites, etc.

c. Subarea rainfall-runoff analysis of historic events.

Develop historic storm events, and subarea loss rate and

unit hydrograph data for ungaged areas.

d. Channel routing characteristics. Determine based

on information in Appendix D (Paragraph D-3d).

e. Assemble, debug HEC-1 model.

C-4. Hydraulic Studies

a. Prepare Water Surface Profile Data--Code HEC-2

model of study reach, after receipt of surveys. Estimate

“n” values, section locations, bridge routines applicable,

effective flow areas. Debug model.

b. Calibrate HEC-2 model to gage data and highwater marks from recent floods.

c. Develop storage-outflow relationships and flood

wave travel time, by routing reach, for information

required in Paragraph C-3d above.

C-5. Calibration of Models to Historic Events

Calibrate the HEC-1 and -2 models to recorded events

and high-water marks. Make preliminary selection of

hydrologic and hydraulic model parameters for hypothetical flood event analysis.

C-6. Frequency Analysis for Existing Land Use

Conditions

a. Perform statistical analysis of gaged data for

peak discharge-frequency relationship. Also estimate

C-1
EP 1110-2-9

31 Jul 94

discharge-frequency relationships through available/

applicable regression equations at key locations, to use in

later comparisons.

b. Hypothetical Storms (HEC-1)--Develop hypothetical frequency storm data from the National Oceanic and

Atmospheric Administration HYDRO 35, and National

Weather Service Technical Publications 40 and 49.

Develop the Standard Project Storm. Develop rainfall

pattern for each storm, including precipitation depth-area

adjustments. Develop corresponding hydrograph for each

hypothetical event throughout the basin using the calibrated hydrologic model of Paragraph C-5.

c. If judged appropriate, further calibrate model to

reproduce the peak discharge calculated from the statistical analysis at the gage site. Emphasize the 2-year

through 10-year event, since the data record is short.

Make adjustments to loss rates and unit hydrograph coefficients for rarer events, as judged reasonable. Compare

results to statistical and regression-derived peak discharge

frequency relationships; further adjust coefficients as

considered reasonable.

d. Using the results of steps a., b., and c., above,

adopt a discharge-frequency relationship at each needed

location. Develop probability distribution of discharge

uncertainty for use in risk-based analyses.

e. Determine corresponding water surface profiles

and inundated areas for selected frequencies at required

locations. Furnish data to planning and economics.

f. Adopt stage-discharge relationship at each required

location for damage computations. At the gage site with

15 years of data, determine deviations about the adopted

stage-discharge relationship. Further evaluate through

sensitivity studies. Develop probability distribution of

stage uncertainty for risk-based analysis.

C-7. Future Without-Project Analysis

Determine future stage-discharge relationships, based on

future watershed changes affecting the hydraulics. If

necessary, adjust discharge-frequency and stage-discharge

risk/uncertainty relationships. Furnish data to economics.

C-8. Levee Alternative Evaluations

For the preliminary levee alignment, develop revised

discharge-frequency and stage-frequency relationships for

each of the three different levee heights. If judged necessary, determine revised stage-discharge risk/uncertainty

relationship. Roughly size a “minimum facility” interior

flood control system for each. With the economist, perform risk and uncertainty studies to establish the claimable level of protection (risk-based) and average annual

benefits resulting for each.

C-9. Levee and Channel Alternative Evaluation

a. For two sizes of channel, reestablish stagefrequency relationships for each of three levee sizes (six

alternatives). Evaluate the discharge and stage uncertainties for with-project conditions. Roughly size a “minimum facility” interior system for each alternative, if

necessary. With the economist, perform a risk-based

analysis to determine project benefits and claimable level

of protection for each alternative. Perform qualitative

sediment analyses for channel modifications to roughly

determine dredging frequency for channel maintenance.

After economic analysis to tentatively establish the NED

plan (levee height) from among the nine alternatives,

design top of levee grade for controlled overtopping.

b. If a channel modification is included in the NED

plan, perform sensitivity tests to determine the importance

of channel maintenance assumptions and costs on the

NED plan. If a more conservative sedimentation analysis

results in significant cost increases, possibly invalidating

the NED plan, additional sediment analyses will be

required in feasibility. Hydrologic engineering work for a

quantitative sediment analysis is not included in this estimate. Adjust final levee grade for any sediment effects.

c. As necessary, furnish hydrologic information, as it

becomes available, to other study team members: stageduration and frequency to environmental, data for Environmental Assessment Report, etc.

d. Nonstructural analysis of emergency procedures in

the event of levee overtopping--evacuation and flood

warning.

C-10. Residual Flooding and Interior Flood

Control

a. Establish residual flooding for remaining flood

damages with the NED project. Evaluate higher levels of

interior flooding protection compared to the “minimum

facility.” Interior flood control measures are distinguished

from minimum facilities in that these additional measures

require net benefits and minimum facilities do not require

incremental economic justification, only cost-effective

design.

C-2
EP 1110-2-9

31 Jul 94

(1) Using the Interior Flood Hydrology Program,

evalu ate two gravity outlets larger than the “minimum

facility” at each of the three gravity drain locations.

(2) Evaluate interior excavated storage at the only site

where it is currently thought feasible.

(3) Evaluate three capacities of pumping plants at

each of two sites.

(4) Evaluate interior ditch improvements for the two

main ditches.

b. Forward data to an economist and cost engineer

for each increment. Supply hydrologic data for wetland

determination and mitigation, as necessary.

C-11. Hydraulic Studies

Some of the design work will have already been incorporated in the above activities.

a. Levees--levee design profile, controlled overtopping design, gravity drain design for “minimum facility,”

etc.

b. Channels--channel geometry, bridge modifications,

scour protection, channel cleanout requirements, channel

and bridge transition design, etc.

c. Drains--size, slope, material, inlet/outlet, operation

procedures, etc.

d. Pumping--capacities, start-stop pump elevations,

sump design, outlet design, scour protection, operating

floor elevations, etc.

C-12. Hydrologic Engineering Reporting

Requirements

a. Project Management Plan--Estimate major hydrologic engineering activities in the preconstruction engineering and design (PED) phase, prepare initial HEMP for

PED work, prepare time and cost for hydrologic engineering, activity schedule.

b. Hydrologic Engineering Appendix to the Feasibility Report--Using the detailed HEMP as appropriate,

outline and write the text, prepare tables and figures.

c. Environmental Assessment Report--Provide data

to environmental section. Supply text, figures, plates, as

needed.

C-3
EP 1110-2-9

31 Jul 94

Appendix D

Generic Detailed Hydrologic Engineering

Management Plan (HEMP) for a Flood

Damage Reduction Study

D-1. General

This sample detailed HEMP would be appropriate for the

hydrologic and hydraulic analysis associated with a typical Corps feasibility report for an urban watershed. It

would be prepared at the end of reconnaissance-phase

study or start of the feasibility phase. The intent of the

hydrologic engineering analysis would be to determine

existing and future discharge-frequency and stagedischarge relationships at key points in the study area,

along with flooded area maps by frequency. This analysis

would be performed without project and for various flood

reduction components that are considered feasible for

relief of the flood problem.

D-2. Preliminary Investigations

This initial phase includes a literature review of previous

reports, obtaining the available data, and requesting additional information needed to perform the investigation.

a. Initial preparation.

(1) Confer with the other disciplines involved in the

study to determine the objectives, the hydrologic engineering information requirements of the study for other disciplines, study constraints, etc.

(2) Scope study objectives and purpose.

(3) Review available documents.

(a) U.S. Geological Survey reports.

(b) Previous Corps work.

(c) Local studies.

(d) Hydrologic engineering analysis for reconnaissance report.

(e) Initial Project Management Plan.

(f) Other.

(4) Obtain hydrologic (historic and design discharges, discharge-frequency relationships, etc.) and

hydraulic (high-water marks, bridge designs, cross sections, etc.) data.

(a) Local agencies (city/county highway departments, land use planning, etc.).

(b) State (state highway departments, planning agencies, water resource agencies, etc.).

(c) Federal U.S. Geological Survey (USGS),

U.S. Soil Conservation Service (SCS), U.S. Bureau of

Reclamation (USBR), etc.

(d) Railroads.

(e) Industries.

(f) Other.

(5) Scope major hydrologic and hydraulic activities.

(6) Prepare detailed HEMP.

(7) Obtain study area maps.

(a) County highway maps.

(b) USGS topographic quadrangle maps.

(c) Aerial photographs.

(d) Others.

(8) Estimate location of cross sections on maps

(floodplain contractions, expansions, bridges, etc). Determine mapping requirements (orthophoto) in conjunction

with other disciplines.

b. Field reconnaissance.

(1) Interview local agencies, and residents along the

stream, review newspaper files, etc., for historic flood

data (high-water marks, frequency of road overtopping,

direction of flow, land use changes, stream changes, etc.).

Document names, locations, and other data for future

reference.

(2) Finalize cross-section locations/mapping

requirements.

D-1
EP 1110-2-9

31 Jul 94

(3) Determine initial estimate of “n” values for later

use in water surface profile computations.

(4) Take photographs or slides of bridges, construction, hydraulic structures, and floodplain channels and

overbank areas at cross-section locations. Consider dictating notes to a hand-held tape recorder to get a complete

and detailed record.

c. Survey request. Write survey request for mapping

requirements and/or cross sections and high-water marks.

D-3. Development of Basin Model (HEC-1)

This phase of the analysis involves the selection of historic events to be evaluated, the development of runoff

parameters from gaged data (and/or regional data from

previous studies) and correlating these data to ungaged

basins and the calibration of the basin model to historic

flood events. This step assumes that at least some recording stream gage data are in or near the study watershed.

a. Calibration of runoff parameters.

(1) Select historic events to be evaluated based on

available streamflow records, rainfall records, high-water

marks, etc.).

(2) From USGS rating curves and time-versus-stage

relationships for each event, develop discharge hydrographs at each continuously recording stream gage. Estimate peak discharge from flood crest gages.

(3) Develop physical basin characteristics (drainage

areas, slope, length, etc.) for basin above each stream

gage.

(4) Select computation time interval ( t) for this and

subsequent analyses. The computation interval must:

(a) Adequately define the peak discharge of hydrographs at gages.

(b) Consider type of routing and reach travel times.

(c) Have three to four points on the rising limb of the

unit hydrograph for the smallest subarea of interest.

(d) Consider types of alternatives and future

assessments.

(5) Using all appropriate rain gages (continuous and

daily), develop historic storm patterns that correspond to

the selected recorded runoff events for the basins above

the stream gages.

(a) Average subarea totals from isoheytal maps or

total gage precipitation weightings.

(b) Temporal distribution from weightings of nearby

recording rain gages.

(6) Determine best estimate unit hydrograph and

loss rate parameters for each event at each stream gage by

calibrating to recorded flood hydrographs.

(7) Make adjustments for better and more consistent

results between events at each stream gage. Adjustments

are made to:

(a) Starting values of parameters and/or

(b) Rainfall totals or patterns (different weightings

of rain gages).

(8) Hold constant the most stable parameters, or

relationships between parameters, and resimulate rainfall/runoff process to estimate other parameters.

(9) Adopt final unit hydrograph and base flow

parameters for each gaged basin.

(10) Re-simulate with adopted parameters held constant to estimate loss rates.

(11) Use adopted parameters of unit hydrographs, loss

rates, and base flow to reconstitute other recorded events

not used in the above calibration to test the correctness of

the adopted parameters and to “verify” the calibration

results.

b. Delineation of subareas. Subareas are delineated

at locations where hydrologic data are required and where

physical characteristics change significantly.

(1) Index locations where economic damage computations are to be performed.

(2) Stream gage locations.

(3) General topology of stream system.

(a) Major tributaries.

(b) Significant changes in land use.

D-2
EP 1110-2-9

31 Jul 94

(c) Significant changes in soil type.

(d) Other.

(4) Routing reaches.

(5) Location of existing physical works (reservoirs,

diversions, etc.) and potential location of alternate flood

reduction measures to be studied.

c. Subarea rainfall-runoff analysis of historic events.

(1) Subarea rainfall.

(a) Average subarea rainfall from isohyetal maps or

weighting of total gage precipitation.

(b) Temporal distribution from weighing in accordance with information from nearby recording rain gages.

(2) Average subarea loss rates.

(a) From adopted values of parameter calibration.

(b) From previous studies of similar basins in the

region.

(c) Others.

(3) Unit Hydrograph Parameters.

(a) From relationships based on calibration results at

stream gages (Section II) and physical basin

characteristics.

(b) From previous regional study relationships of unit

hydrograph parameters and physical basin characteristics.

(c) From similar gaged or known basins.

(d) From judgment, if no data are available.

d. Channel routing characteristics.

(1) Modified Puls from water surface profile computations (Hydrologic Engineering Center (HEC-2)).

(2) Optimized from stream gage data (HEC-1).

(3) Adopted parameters from previous studies, experience, etc.

(4) Derived from reach hydraulics (Muskingum -

Cunge).

e. Reservoir routing (if reservoirs are present). This

type of routing must be performed where storage has a

significant effect on reach outflow values, with reservoirs

being the most notable example. However, one must also

apply these techniques where physical features warrant,

such as roads crossing a floodplain on a high fill, especially where culverts are used to pass the flow

downstream.

(1) Develop surface area-capacity data (elevationsurface area-storage relationships).

(2) Develop storage-outflow functions based on outlet

works characteristics.

f. Runoff hydrographs. Using the subdivided rainfall-runoff model, including existing projects and the

routing information of Section D-3 above, generate runoff

hydrographs for previously selected runoff events at

desired locations. Final calibration of the hydrologic

model is described in Section D-5.

D-4. Hydraulic Studies

These studies are used to determine water surface profiles,

economic damage reaches, and modified Puls channel

routing criteria (if used). This example assumes that an

evaluation was previously made that a steady flow-rigid

boundary water surface profile analysis is appropriate.

a. Prepare water surface profile data.

(1) Cross sections (tabulate data for each section).

(a) Make cross sections perpendicular to flow.

(b) Each cross section should be typical of the reach

from half the distance to the next section both upstream

and downstream of the current locations.

(c) Develop effective flow areas. If modified Puls

routing criteria are to be determined from water surface

profile analyses, the entire section must be used (for storage) with high “n” values in the non-effective flow areas.

(2) Refine “n” values from field reconnaissance and

from analytical calculation and/or comparison with “n”

values determined analytically from similar streams.

D-3
EP 1110-2-9

31 Jul 94

(3) Bridge computations--estimate how high the

selected floods will reach on each bridge and select either:

(a) Normal bridge routine.

(b) Special bridge routine.

(4) Develop cross sections above and below bridges

to model effective bridge flow (use artificial levees or

ineffective flow area options, as appropriate).

b. Proportion discharges. Proportion discharges

based on hydrologic analyses of historic storms and plot

peak discharge versus river mile. Compute a series of

water surface profiles for a range of discharges. Analysis

should start below study area so that profiles will converge to proper elevations at study limits. May want to

try several starting elevations for the series of initial

discharges.

c. Manual check. Manually check all large differences in water surface elevations across the bridge, say,

greater than 3 ft.

d. Results. The results are a series of rating curves at

desired locations (and profiles) that may be used in subsequent analyses. Additional results are a set of storage

versus outflow data by reach which, along with an estimate of hydrograph travel time, allow the development of

modified Puls data for the hydrologic model.

D-5. Calibration of Models to Historic Events

a. General. This study step concentrates on

“de-bugging” the hydrologic and hydraulic models by

recreating actual historic events, thereby gaining confidence that the models are reproducing the observed

hydrologic responses. This effort would continue from

the activities described in Paragraph D-3.

b. Calibration procedure.

(1) Check historic hydrographs against recorded data,

make adjustments to model parameters, and rerun the

model.

(2) If no stream gages exist, check discharges at

rating curves developed from water surface profiles at

high-water marks.

(3) Adjust models to correlate with high-water marks.

(4) Adopt hydrologic and hydraulic model parameters

for hypothetical flood event analysis.

(5) Quantify uncertainty of the stage-discharge relationship at each site where damage analysis is to be

performed. As appropriate, use recorded gage data, comparison of profile to high-water marks, minimum deviation, and engineering judgement.

D-6. Frequency Analysis for Existing Land-Use

Conditions

The next phase of the analysis addresses how often specific flood levels will occur at all required points in the

study watershed. The procedures include developing

discharge-and stage-frequency relationships at stream

gages (when available) through statistical analysis using

recorded peak discharges and at other required locations

using available hypothetical storm data.

a. Statistical analysis. Using the procedures

described in Bulletin 17B (Water Resources Council

1982), determine and plot analytical and graphical frequency curves at each stream gage. Adopt stage/

discharge frequency relations at each gage. Regional

relationships, regression analyses, and the results of hypothetical storm studies will be used to extend the records

for rarer floods.

b. Hypothetical storms (HEC-1).

(1) Obtain hypothetical frequency storm data from the

National Oceanic and Atmospheric Administration

(NOAA) HYDRO 35, National Weather Service (NWS)

Technical Publications (TP) 40 and 49, or from appropriate other sources. Where appropriate, develop the

Standard Project and/or the Probable Maximum Storm.

(2) Develop a rainfall pattern for each storm. Include

precipitation depth-area adjustments, where necessary.

(3) Develop a corresponding hydrograph for each

hypothetical event throughout the basin using the calibrated hydrologic model.

(4) If deemed necessary, calibrate model of each frequency event to known frequency curves. Adjust loss

rates, base flow, etc. as required, while remaining within

reasonable limits for each parameter. The peak flow frequency at each ungaged area is assumed to be consistent

with calibrated peak flow frequencies at gaged locations.

D-4
EP 1110-2-9

31 Jul 94

(5) If streamflow data are insufficient to develop analytical frequency curves, use the following procedure:

(a) Obtain frequency curves from similar nearby

gaged basins.

(b) Develop frequency curves at locations of interest

from previous regional studies (USGS, Corps of Engineers, State, etc.).

(c) Determine frequency hydrographs for each event

from hydrologic model and develop a corresponding frequency curve at the locations of interest throughout the

basin.

(d) Plot all the frequency curves (including those

using other methods if available) and, based on engineering judgement, adopt a frequency curve. The adopted

curve may not be any of the developed curves, but simply

the best estimate based on the available data.

(e) Calibrate the hydrologic model of each frequency

event to the adopted frequency curve. The frequency

curve at other locations may be determined from the

calibrated model results, assuming consistent peak flow

frequencies.

(6) Quantify the uncertainty in the dischargefrequency relationship at all locations where damage

computations will be performed. As appropriate, use gage

data, regression equations, calibrated models to determine

equivalent length of record.

(7) Determine corresponding water surface elevations

and profiles for selected frequencies from the rating

curves developed by the water surface profile evaluations.

D-7. Future Without-Project Analysis

Where hydrologic and/or hydraulic conditions are

expected to significantly change over the project life,

these changes must be incorporated into the hydrologic

engineering analysis. Urbanization effects on watershed

runoff are the usual future conditions analyzed.

a. From future land use planning information

obtained during the preliminary investigation phase, identify areas of future urbanization or intensification of existing urbanization.

(1) Types of land use (residential, commercial, industrial, etc.).

(2) Storm drainage requirements of the community

(storm sewer design frequency, on-site detention, etc.).

(3) Other considerations and information.

b. Select future years in which to determine project

hydrology.

(1) At start of project operation (existing conditions

may be appropriate).

(2) At some year during the project life (often the

same year as whatever land use planning information is

available).

c. Adjust model hydrology parameters for all subareas

affected by future land use changes.

(1) Unit hydrograph coefficients, usually reflecting

decreased time-to-peak and decreased storage.

(2) Loss rate coefficients, usually reflecting increased

imperviousness and decreasing infiltration characteristics.

(3) Routing coefficients, usually reflecting decreased

travel times and storage capabilities.

d. Operate the hydrology model and determine additional discharge-frequency relationships throughout the

watershed that represent future, without-project conditions.

e. Evaluate the need to adjust uncertainty parameters

of stage-discharge and discharge-frequency relationships,

compared to existing conditions.

D-8. Alternative Evaluations

For the alternatives jointly developed with the members of

the interdisciplinary planning team, modify the hydrologic

and/or hydraulic models to develop the effects of each

alternative (individually and in combination) on flood

levels. Alternatives can be either structural (reservoirs,

levees, channelization, diversions, pumping, etc.) or nonstructural (flood forecasting and warning, structure raising

or relocation, floodproofing, etc.). Considerable less

hydrologic engineering effort is necessary for modeling

non-structural alternatives compared to structural.

a. Procedure.

(1) Consider duplicating existing and future withouthydrologic engineering models for individual analysis of

D-5
EP 1110-2-9

31 Jul 94

each alternative or component. The results provide existing and future, with-project information for each alternative to be evaluated.

(2) Most structural components are usually modeled

by modifying storage-outflow relationships at the component location and/or modifying hydraulic geometry

through the reach under consideration.

(a) Reservoirs--adjust storage-outflow relationships

based on spillway geometry and height of dam.

(b) Levees--adjust cross-section geometry based on

proposed levee height(s). Evaluate effect of storage loss

behind levee on storage-outflow relationships and determine revised discharge- and stage-frequency relationships

downstream, if considered significant. Develop uncertainty relationship for the revised stage-discharge function.

(c) Channels--adjust cross-section geometry based on

proposed channel dimensions. Evaluate effect of channel

cross section and length of channelization on floodplain

storage, modify storage-outflow in reach, and determine

revised downstream discharge-frequency relationships, if

considered significant.

(d) Diversions--adjust hydrology model for reduced

flow downstream of the diversion and to identify where

diverted flow rejoins the stream (if it does).

(e) Pumping--adjust hydrology model for various

pumping capacities to be analyzed.

(3) Evaluate the effects of potential components on

the sediment regime. Refer to guidance given in

EM 1110-2-4000.

(a) Qualitatively--for initial screening.

(b) Quantitatively (where necessary)--for final

selection.

b. Nonstructural components.

(1) Floodproofing/structure raises--elevations of

design events primarily.

(2) Flood forecasting--development of real-time

hydrology model, determination of warning times, etc.

c. Alternative evaluation and selection.

(1) Alternative evaluation and selection is an iterative

process, requiring continuous exchange of information

between a variety of disciplines. An exact work flow or

schematic is not possible for most projects, thus Paragraph D-7 could be relatively straightforward for one or

two components or quite complex, requiring numerous

reiterations as more cost and design information is known

and project refinements are made. Paragraph D-7 is usually the area of the HEMP requiring the most time and

cost contingencies.

(2) For the selected alternative, provide hydrologic

information to environmental engineers for use in studies

concerning the effects of the recommended project.

D-9. Hydraulic Design

This paragraph and Paragraph D-8 are partly intertwined,

as hydraulic design must be included with the sizing of

the various components, both to operate hydrologic engineering models and to provide sufficient information for

design and costing purposes. Perform hydraulic design

studies commensurate with the level of detail of the study

process.

a. Reservoirs. Dam height, spillway geometry, spillway cross section, outlet works (floor elevation, length,

appurtenances, etc.), scour protection, pool guidetaking

line, etc.

b. Levees. Levee design profile, interior flood control

requirements, etc.

c. Channels. Channel geometry, bridge modifications, scour protection, channel cleanout requirements,

channel and bridge transition design, etc.

d. Diversions. May be similar to channel design

activities, also would include diversion control (weir,

gates, etc.). Where the diversions are tunnels, open channel flow and pressure conduit hydraulic analyses may be

necessary, depending on tunnel capacity and range of

possible discharges.

e. Pumping. Capacities, start-stop pump elevations,

sump design, outlet design, scour protection, etc.

D-6
EP 1110-2-9

31 Jul 94

f. Nonstructural. Floodproofing or structure raise

elevations, flood forecasting models, evacuation plan, etc.

D-10. Hydrologic Engineering Reporting

Requirements

The last step must thoroughly document the results of the

technical analyses in report form. Hydrologic and

hydraulic information presented will range from extensive

for feasibility reports to minimal for a typical Feature

Design Memorandum (FDM(s)).

a. Project Management Plan.

(1) Major hydrologic engineering activities in the

preconstruction engineering and design (PED) phase.

(2) Time and cost for hydrologic engineering.

(3) Activity schedule.

b. Hydrologic Engineering Appendix.

(1) Text.

(2) Tables.

(3) Figures.

c. Environmental Impact Statement/Environmental

Assessment Report.

(1) Hydrologic information/data as necessary.

(2) Portions of text, selected figures and tables.

D-7
EP 1110-2-9

31 Jul 94

Appendix E

Generic Detailed Hydrologic Engineering

Management Plan (HEMP) for a Water

Control Management Study

E-1. Sample HEMP

This sample HEMP can be used as a guide for hydrologic

engineering components of a water control management

study. This appendix assumes that a general plan for

reservoir regulation has been established, which is the

result of a water conservation study (Appendix F), a flood

control study, or new project construction, and that a

water control plan and water control manual are to be

developed. The HEMP covers the development of data

collection procedures, forecasting procedures, drought

detection procedures, development of reservoir regulation

rule curves, and other information. Reference is made to

ER 1110-2-240 and EM 1110-2-3600. Not included in

this appendix are the hydrologic engineering studies

needed for a dam safety plan.

E-2. Preliminary Investigations

This is a preparatory phase that includes scoping the

project, deciding upon and gathering data, coordinating,

etc. (Experience has shown that more than 50 percent of

the study’s budget can be consumed by data gathering and

preparation.)

a. Do initial preparation/coordination.

(1) Identify agencies/parties with which coordination

is needed--for data, operational requirements.

(2) Review existing documents.

(a) Design documents.

(b) Interagency agreements.

(c) Studies by Corps.

(d) Studies by other agencies.

(3) Visit existing project(s).

b. Obtain hydrologic data--see Appendices D and F.

c. Scope major hydrologic activities; choose models

to be used.

d. Prepare detailed HEMP.

E-3. Develop Study Models

Because the water control management study is the final

phase in project development, hydrologic/hydraulic models will most likely have been developed in previous

phases of the project. If additional modeling studies are

required, then data will have to be obtained and model

calibration undertaken. See Appendices D and F. Note

that the development of an operational forecast model is

treated separately, below.

E-4. Develop Seasonal Flood Control Rule Curve

A seasonal guide curve--specifying the upper limit elevation for flood control throughout the year--may have been

developed in earlier study phases; however, this may need

review and refinement for actual regulation. Also, the

object of the water management study might be to modify

the existing rule curve to improve regulation or accommodate a revised policy. This analysis is one of evaluating

flood potential throughout the year. If streamflow records

are short, the analysis could be augmented by looking at

precipitation records to ensure that an adequate sampling

of runoff potential for a given calendar date is achieved.

a. Obtain historic flood data for the project site,

including secondary floods that occur off-season.

(1) Obtain recorder traces from the U.S. Geological

Survey.

(2) Convert traces to streamflow hydrographs.

(3) Compute volumes appropriate to flood control

storage.

b. Review long-period rainfall and streamflow

records in the region to augment project records. Estimate project inflow data through regional correlation

techniques or, perhaps, a rainfall-runoff model.

(1) Decide on a processing technique (DSSMATH,

STATS, etc.).

(2) Enter data into database.

(3) Perform calculations.

(4) Display results; verify for reasonableness.

(5) Use rainfall-runoff model if required.

E-1
EP 1110-2-9

31 Jul 94

(a) Obtain precipitation records.

(b) Calibrate model.

(c) Apply precipitation, compute hydrograph.

(d) Display, verify reasonableness.

c. Compute volume of water stored for each flood,

given the planned flood regulation plan.

(1) Determine computational technique, e.g., spreadsheet, existing model such as the Hydrologic Engineering

Center (HEC-5), etc.

(2) Prepare spreadsheet/model, check with test data.

(3) Establish regulation rules, assumptions of forecast

knowledge.

(4) Perform routings using newly derived inflow data.

(5) Display results, review for reasonableness.

d. Construct seasonal flood control rule curve.

(1) Plot storage requirement as a function of date.

(2) Plot tentative envelope line representing rule

curve. Incorporate limitations for rate of draft, etc.

(3) Identify outlier points, estimate probability of

event. Decide whether to envelop or not.

(4) Identify impacts on other project functions and

compare with rule curves used in project authorization.

(5) Decide upon final rule curve.

E-5. Develop Forecasting Model

Assess whether the project under consideration warrants a

forecast model as a part of the reservoir regulation activities, and whether staffing is available to maintain and

operate the model. If that assessment is affirmative, then

a model is needed for future operational application. It is

likely that an existing study model can be used as a basis

for development of the forecasting model. Assess

whether forecasting is also to be done for conservation

operation purposes, as well as flood control. If so, a

continuous model capable of forecasting low-flow conditions might be the appropriate choice.

a. Select computer program (HEC-1F, SSARR, etc.)

to be used. Factors to be considered are: size and complexity of basin (reservoir projects, diversions, etc.); type

of runoff regime (rain, snow, flash flood potential); and

applications required (flood operations, low-flow

forecasting).

(1) Review information and models; consult as

necessary with users and experts.

(2) Obtain models, run tests.

(3) Evaluate resources needed for real-time application (computers, people, funds).

(4) Select model.

b. Review historic and real-time data availability and

obtain hydrometeorological data pertinent to forecasting

and project operation. Process data for input to forecast

model.

(1) Set up forecast database (likely (HEC-Data Storage System)).

(2) Consider data types needed (precipitation, temperature, streamflow, etc.).

(3) Examine period of record and select flood events

that should be used in calibrations.

(4) Obtain data and download to database.

(5) Perform data screening/data display to verify

data.

c. Choose likely hydromet station candidates for

real-time application.

(1) Review performance of existing real-time

telemetry.

(2) Examine feasibility of providing future

automation.

(3) Determine relative merit of stations as indices to

forecasting runoff.

(a) Compute correlations of precipitation versus

runoff.

E-2
EP 1110-2-9

31 Jul 94

(b) Examine locations so that a range of elevation

and spacial coverage is obtained.

(4) Select likely best candidates.

d. Configure model for operational forecast application. This might be an expansion or a simplification of

the study model, if available.

(1) Develop model characteristics.

(a) Project characteristics (storage tables, outflow

limits, etc.).

(b) Routing reaches (initial estimates of routing

factors).

(c) Basin configuration (combining points, diversions,

balances, etc.).

(2) Estimate initial hydromet station weightings.

e. Perform calibration simulations with model with

proposed operational data and operational model. Repeat

process of calibration and hydromet station selection until

best model is configured.

(1) Flood runoff calibrations (rain/runoff model).

(a) Decide on calibration procedure (trial/error,

optimization).

(b) Select events for calibration (or continuous

simulation).

(c) Make calibration simulation.

(d) Make changes and repeat.

(2) Routing calibration (same process as above).

f. Set up procedures for preparing forecast in real

time.

(1) Initialization of forecast run.

(2) Estimating missing data.

(3) Estimating ungaged local inflow.

(4) Incorporation of quantitative precipitation

forecasts.

(5) Estimating snowmelt.

g. Test applications of forecast model with forecast/

regulation personnel.

h. Document forecast procedures.

E-6. Develop a Plan for the Water Control Data

System (WCDS) and the WCDS Master Plan

The development of forecasting procedures will reveal

remote gaging needs, whether it be the installation of new

stations or the automation of manually reported stations.

The WCDS also includes the computer facilities needed

for processing data and executing computer models.

These developments are documented in the WCDS Master

Plan, which is submitted to higher authority for approval.

a. Establish field requirements for operational data.

(1) Determine frequency of reporting, backup

requirements.

(2) Automate existing facilities, if needed.

(3) Establish new stations as necessary.

b. Develop plan for field data collection system--

land-line, GOES, line-of-sight radio, etc.

(1) Obtain manufacturer’s specifications and costs.

(2) Coordinate with other water resource agencies

collecting data in the region. Consult with the Corps of

Engineers, Civil Works, Engineering Division, Hydrology

and Hydraulics Branch (CECW-EH).

(3) Estimate costs for maintenance--field equipment

and receiving site.

(4) Prepare life-cycle cost analysis comparison;

select best alternative.

c. Develop plan for WCDS computer processing.

(1) Consult with CECW-EH, HEC, Information

Management, and other Corps offices.

(2) Obtain manufacturer’s specifications and costs.

(3) Determine software requirements.

E-3
EP 1110-2-9

31 Jul 94

(4) Determine continuity of operations requirements.

(5) Perform life-cycle cost analysis; select best

alternative.

d. Write WCDS Master Plan; submit for approval.

e. Establish capital and annual expenditure requirements; budget accordingly (Plant Replacement and

Improvement Program (PRIP) and annual funds).

E-7. Develop Flood Control Operation Guidance

The water control plan for flood control operations should

include several items to assist regulators and project operators in making regulating decisions. These may require

new hydrologic and hydraulic studies, or they may simply

require development of existing material for presentation

in the water control manual.

a. Regulating outlet and spillway gate opening

sequences, limitations.

(1) Consult with hydraulic design engineers; project

personnel.

(2) Perform or request special hydraulic analysis as

required.

(3) Document procedures with text and diagrams as

necessary.

b. Spillway gate regulation procedures.

(1) Review guidance and design documents regarding

gate regulation schedules.

(2) Prepare a gate regulation diagram.

(a) Select a design flood for recession volume

analysis.

(b) Perform routings.

(c) Plot required outflows versus inflow and storage.

(3) Test diagram by routing with different floods

(inflow design flood, historic floods). Adjust as

necessary.

(4) Finalize guidance plots; prepare documentation.

c. Miscellaneous guidance curves for flood control

operations. There may be need for guidance curves and

rules that can be used in the flood control operating plan

in lieu of or, in conjunction with, a flood forecasting

operation. One application would be as a backup to a

forecasting system in cases where communications and

power are lost. Examples might be: indices to runoff,

given precipitation magnitudes; procedures for changing

outflows, given reservoir rate of fill; and rules for operating several dams controlling a single control downstream

control point.

(1) Determine need for guidance, considering factors

such as:

(a) Remoteness of project; communications and

transportation viability.

(b) Accuracy and viability of operational forecasting

procedures, models.

(c) Basin runoff response.

(2) Perform hydrologic study using models or

manual analysis.

(3) Test guidance on historic floods, design floods.

(4) Prepare plots, narrative text.

d. Examples of flood regulation. Examples of flood

control regulation provide a useful form of guidance for

water control manuals. These can be plots and/or tabulations, accompanied by explanatory text.

(1) Select floods for possible examples, considering

factors such as: magnitude of flood; unusual runoff timing or shape of hydrograph; seasonal considerations; and

ability to demonstrate use of guidance procedures.

(2) Perform reservoir routings with historic data,

using guidance materials that have been prepared.

(3) Plot hydrographs; prepare narrative material.

e. Emergency instructions to dam tenders when

communication is lost. This is a mandatory requirement

for dams subject to rapid flood runoff requiring gate

operations. It is particularly important for dams in remote

areas. Coordination is needed with Dam Safety Plan

emergency procedures.

E-4
EP 1110-2-9

31 Jul 94

(1) Review operating guidance determined in above

paragraphs.

(2) Review staffing, travel conditions, and timing for

dam tenders with project personnel. Visit project if

necessary.

(3) Prepare procedures for non-guided operation:

(a) Staffing requirements.

(b) Data gathering; project monitoring.

(c) Determination of outflows.

(d) Alert procedures.

E-8. Develop Guidance for Conservation

Operation

Although not as critical as flood operation guidance

because timing and possible emergency conditions are not

as problematic, there may be special procedures which are

required for low-flow operations. Examples might be

(1) procedures for determining instream flow releases as a

function of reservoir status, and (2) municipal and industrial release schedules, etc. This activity might be a part

of the Drought Contingency Plan studies, Paragraph E-10.

a. Determine need for guidance.

(1) Review studies used for project formulation and

design.

(2) Review historic records; select drought periods

for examination.

(3) Consult with affected agencies/parties.

(4) Decide on need for further analysis and need for

special guidance.

b. Perform hydrologic study as required, using models or manual procedures. (Refer to Paragraphs F-4

and F-5 in Appendix F for details.)

c. Test guidance on varying hydrologic conditions,

considering real-time conditions such as forecasting accuracy or slippage in implementing actions.

d. Prepare plots, narrative description for water control manual. (Refer to Paragraph E-11, below.)

E-9. Development of Guidance for Hydroelectric

Operations

The design of the hydro plant for the project and the

nature of the hydroelectric system involved will determine

how the project is to be operated for power production, so

additional hydrologic engineering studies for the water

control plan may not be extensive. Possible items:

(1) rate-of-change restriction studies, including possible

river fluctuation studies; (2) block-loading schedules;

(3) plant characteristic charts; and (4) unit operating procedures. Refer to EM 1110-2-1701.

a. Identify need for guidance. (See Paragraph E-8,

above.)

b. Perform analysis. (Refer to Paragraphs F-4 and

F-5 in Appendix F for details.)

c. Prepare material for Water Control Manual.

(Refer to Paragraph E-11, below.)

E-10. Develop Drought Contingency Plan

If the project has a water conservation operating objective,

then a Drought Contingency Plan is required in the Water

Control Manual. Reference is made to ER 1110-2-1941.

E-11. Prepare Water Control Plan and Manual

The final step in the water control management study is

the documentation of the plan of operation in the water

control manual. If the plan that has been developed represents a significant change in operation from previous

operational policy, then public coordination is required if

it hasn’t already taken place. Refer to ETL 1110-2-251.

a. Ascertain need for public meeting on Water Control Plan. (Refer to WRDA 90, Sec. 3106.) Prepare

materials and hold meeting if required.

b. If meeting is required, prepare briefing material

and hold meeting.

(1) Decide on presentations to be made.

(2) Review studies, availability of briefing material.

(3) Prepare new visual aids as necessary.

(4) Hold meeting.

E-5
EP 1110-2-9

31 Jul 94

(5) Carry out follow-up actions as necessary.

c. Establish manual content, organization, and work

program.

(1) Prepare outline of manual.

(2) Assemble material; identify critical items to be

worked on.

(3) Assess human resources requirements, time

schedule, funds.

(4) Consider contractor assistance.

(5) Obtain agreement and approval of content and

approach. Review with division office.

d. Prepare manual.

(1) Decide on plotting methodology.

(2) Prepare required plots and graphics.

(3) Prepare narrative material.

(4) Conduct first draft review by in-house personnel,

division office.

(5) Prepare final manual for approval.

E-6
EP 1110-2-9

31 Jul 94

Appendix F

Generic Detailed Hydrologic Engineering

Management Plan (HEMP) for a Water

Supply Investigation

F-1. Sample Detailed HEMP

This sample detailed HEMP can be used as a guide for

the hydrologic and hydraulic analysis needed for conducting a water conservation or a storage reallocation study.

Examples might include: a water supply allocation plan

for a new reservoir project; a drought operating plan for

an existing reservoir project or system of projects; and a

system-wide reevaluation of a master water control plan

considering the potential of benefit reallocation. The

analysis would typically employ a reservoir simulation

model such as the Hydrologic Engineering Center

(HEC)-5 or HEC- Prescriptive Reservoir Model (PRM).

Flood control criteria might affect conservation purposes;

therefore, flood routing studies may be required, and

perhaps a rainfall-runoff model would be employed. The

goal would be to evaluate nominated alternatives of storage quantities, firm water supply yields, seasonal rule

curves, and instream flow goals by model simulation.

The alternatives would be judged by comparing regulated

flood frequency curves, low-flow frequency curves, reservoir elevation-duration curves, etc.

F-2. Preliminary Investigations

This is a preparatory phase that includes scoping the

project, deciding upon and gathering data, coordinating

with agencies affected by the study, etc. (Experience has

shown that more than 50 percent of the study’s budget

can be consumed by data gathering and preparation.)

a. Initial preparation.

(1) Identify agencies/parties with which coordination

is needed - for data, operational requirements.

(2) Identify problem, scope study objectives.

(3) Review existing documents.

(a) Design documents.

(b) Interagency agreements.

(c) Previous studies by Corps.

(d) Studies by other agencies.

b. Choice and application of models.

(1) Research, obtain consultation (HEC and others)

on which models to employ and how they can be applied.

c. Obtain historic hydrologic/meteorological data.

(1) Project operating records; e.g., reservoir elevations, outflows.

(2) U.S. Geological Survey (USGS) streamflow

records.

(3) National Weather Service (NWS) precipitation

and temperature data.

(4) Evaporation records.

(5) Snow data.

(6) Irrigation withdrawals.

(7) Consumptive use (municipal and industrial)

records.

d. Obtain project requirements and alternatives to be

investigated.

(1) Municipal and industrial requirements.

(2) Instream flow requirements.

(3) Mandatory reservoir requirements.

(4) Alternative storage capacities.

(5) Future irrigation demands.

e. Scope major hydrologic activities; choose models.

f. Prepare detailed HEMP.

F-3. Develop Hydrologic Data for Analysis

a. Load raw data into study database (usually HECData Storage System (HECDSS)).

(1) Develop naming conventions/database structure.

Ascertain computer requirements. Consult with experts

where necessary.

F-1
EP 1110-2-9

31 Jul 94

(2) Download data from various sources.

(3) Rough check data viability by display or screening processor.

b. Process hydrologic data for model input (streamflow data). This is a very important and potentially

time-consuming step in which a uniform database of

streamflow is derived, to be used as inflows in reservoir

regulation models. Although monthly data are typically

used, a shorter time period (daily or more frequent) may

have to be developed if flood regulation analysis is

involved. Take full advantage of HEC-DSS-linked programs (STATS, DSSMATH, etc.) to evaluate and process

data.

(1) Perform cross-station checks such as double-mass

plots to reveal record inconsistencies. Evaluate and correct as necessary.

(2) Decide on period of record to be used, considering data availability and incorporation of significant

events.

(3) Estimate missing data.

(4) Compute storage changes at upstream reservoirs.

Adjust historic records to remove effects of historic

upstream reservoir regulation.

(a) Convert elevations to storage, if necessary, for

each project.

(b) Calculate adjusted streamflow at downstream

stream gages.

(c) Accumulate storage adjustments where more than

one reservoir is involved.

(d) Produce tabulations, statistical summaries for

checks.

(5) Process/estimate irrigation depletion data. Correct

historic records for changes in irrigation diversions.

(a) Review irrigation records; determine magnitude of

impact on study.

(b) Decide on scope of effort.

(c) Compute year-by-year historic diversions and

return flows.

(d) Estimate future irrigation depletions.

(e) Compute changes in irrigation: future-historic.

(f) Prepare final computation of corrected flows.

(g) Produce display statistics of final irrigation quantities to be used.

(6) Prepare final computations; display and check

data and formatting for model input.

(a) Perform checking computations to check data

validity (e.g., compute locals).

(b) Prepare final production of statistical summaries,

displays.

(c) Prepare final formatting for model input.

c. Derive synthetic (stochastic) monthly flow record

(optional). In addition to the historic period of monthly

flows, it may be desirable to employ a synthetic flow

sequence, derived by stochastic techniques. This would

be particularly important when multiple-year critical periods are being encountered.

(1) Consult with HEC and others on best available

programs and techniques to derive a stochastic flow

record, given the basin configuration and analysis

requirements.

(2) Review technical publications; find examples of

applications.

(3) Obtain computer programs, run on test data.

(4) Determine scope and cost of work and benefits

of using stochastic record.

(5) Prepare input to stochastic flow generator as program requires.

(6) Analyze output to ascertain its statistical soundness. Revise input as needed.

d. Derive historic or synthetic flood flows. A water

supply investigation or storage allocation study may

require analysis of flood control criteria. If so, historic

and/or synthetic flood hydrographs are needed. Examples

of synthetic floods are design floods such as the Standard

Project Flood; or, different spacial and temporal flood

F-2
EP 1110-2-9

31 Jul 94

patterns that appear plausible but have not been observed

historically. Derivation of such events would employ a

runoff model. (See Appendix D for generic HEMP guidance.)

F-4. Preliminary Analysis

Prior to extensive analysis with hydrologic models (or in

place of, for small-scale studies) it may be desirable to

perform manual, short-cut water conservation analyses.

These include procedures such as (1) mass-curve analysis

for identifying critical periods and estimating firm yields;

(2) limited scope sequential accounting using a spreadsheet or DSSMATH; and (3) low-flow frequency or flowduration analysis.

a. Obtain references and consultation on use of methodology as necessary.

(1) Search literature as necessary.

(2) Consult with HEC and others.

(3) Decide on methodology to use.

b. Obtain or construct spreadsheet, computer programs, or other computational procedures.

(1) Obtain or develop computer code.

(2) Test program/spreadsheet.

(3) Develop display routines.

c. Prepare data input for analysis procedure. (See

Paragraph F-3.)

d. Obtain project demands, requirements.

(1) Analyze requirements for validity.

(2) Prepare input for program being used.

e. Perform analysis with nominated alternatives to be

considered.

(1) Verify technique on current data, if possible.

(2) Execute technique with each alternative.

f. Display results, document as necessary.

F-5. Develop Models for Detailed Study

This phase of the analysis involves the setting up, calibrating, and testing of computer models that are to be

used in the analysis. An important part of this effort also

is the processing of basic data that are needed for the

model simulations. The following outline assumes that a

reservoir simulation model with a monthly time-step (e.g.,

HEC-5) is to be employed, for analysis of seasonal or

multi-year reservoir operations. An additional potential

evaluation preliminary to HEC-5 is the use of HEC-PRM,

a “prescriptive” network-flow model which is used to

investigate relative values of alternative operating objectives and strategies in a reservoir system. Also, for flood

control evaluations a precipitation-runoff model coupled

with a short-term reservoir system and basin routing

model might be needed. This might be HEC-1 and

HEC-5, the North Pacific Division (NPD) SSARR Program (Streamflow Synthesis and Reservoir Regulation), or

the Southwest Division (SWD) Reservoir Simulation and

Routing Program.

a. Derivation of prescriptive model: HEC-PRM

(optional). A prescriptive model can be used in multiplepurpose reservoir systems to help define the most desired

operation, given relative economic values (or penalties)

assigned to operating constraints and objectives.

(1) Consult with HEC and/or other users of this

model.

(2) Obtain program; develop understanding of its

application, requirements, end products.

(3) Decide on use of program and scope of effort.

(4) Formulate basic model structure to represent

reservoir system. Decide upon location of reservoirs,

nodes.

(5) Define penalty functions at nodes and reservoirs.

(a) Coordinate with economics personnel for penalty

function derivation.

(b) Obtain indicators of economic impact versus

flow or stage: flood damage, power values, recreation,

instream flow (fishery, water quality), navigation, irrigation, and municipal and industrial.

(c) Plot penalty functions and input into model.

F-3
EP 1110-2-9

31 Jul 94

(6) Execute model with first estimate of current conditions and constraints.

(7) Check results (seasonal reservoir elevations)

against real-world conditions. Modify penalty functions

to obtain intuitively “calibrated” model. Repeat model

adjusting as necessary.

(8) Perform production runs.

(a) Sensitivity analysis of economic functions.

(b) Potential future changes in operating constraints.

b. Develop descriptive model for monthly routing,

e.g., HEC-5. A descriptive model performs a period-byperiod simulation of reservoir operation following rule

curves and other operating variables. The rule curves

represent alternative possibilities of operation, reflecting

both existing and nominated alternative conditions. Either

may have emerged from the results of the prescriptive

model simulation performed above.

(1) Consult as necessary on use and application of

model. Obtain program and test.

(2) Formulate basic model structure to represent

reservoir system. Decide upon location of reservoirs,

control points.

(3) Prepare reservoir model characteristics.

(a) Reservoir elevation/area/storage capacity tables.

(b) Powerhouse characteristics.

(c) Tailwater ratings.

(d) Outlet constraints (maximum, minimum, rate-ofchange, etc.).

(4) Prepare river system characteristics.

(a) Irrigation diversion relationships.

(b) Routing characteristics (for flood hydrograph

routing).

(c) Natural lake characteristics - elevation/storage/

outflow.

(d) Evaporation.

(5) Prepare reservoir rule curves (existing conditions

if for an existing system).

(a) Seasonal flood control curves.

(b) Seasonal proportional draft curves.

(c) Other rule curves.

(6) Develop procedures for output display and

summary.

(7) Execute model for initial test runs. Check

results for reasonableness against known conditions.

(a) Historic regulated flows at control points.

(b) Historic reservoir elevations.

(c) Historic power generation.

(d) Low flow (7-, 10-day volumes, etc.) and flood

frequency curves.

(8) Adjust model parameters to obtain a calibrated

and tested model. Repeat above steps as necessary.

c. Develop daily (or shorter period) flow routing

model.

(1) Determine basin configuration for model.

(a) Control/damage points.

(b) Routing reaches.

(c) Diversions.

(d) Lake characteristics.

(e) Backwater effects.

(2) Derive routing characteristics for individual

reaches.

(a) Choose routing method and model.

(b) Obtain data to derive routing coefficients.

(c) Determine local inflows.

(d) Perform routings.

F-4
EP 1110-2-9

31 Jul 94

(e) Adjust model characteristics as necessary until

calibration is achieved.

(3) Verify total basin model by simulating historic

records and comparing with observed data.

F-6. Alternative Evaluations

This task is the “heart” of the water control management

study, requiring repeated simulations with nominated

alternatives of reservoir operating policies and procedures.

It would be performed in close coordination with the

interdisciplinary planning team. Alternatives may have

been suggested by the prescriptive model, if used, or by

the team’s agreed-upon formulations.

a. Define nominated alternative; prepare operating

rule curve or other criteria accordingly.

b. Execute model; display and examine results.

(1) Seasonal reservoir elevations - number of refill

failures, frequency curves, etc.

(2) Instream flow frequency, duration.

(3) Flood frequency curves.

(4) Power generation.

(a) Firm energy.

(b) Average energy.

(c) Capacity.

c. Repeat with alternatives; perform sensitivity tests

as necessary.

d. Prepare model results for briefings, public meetings, etc., as necessary.

e. Document results.

F-5