HEC-HMSThe Hydrologic Engineering Center’s Hydrologic Modeling System (HMS)

Summary of Topics - HEC-HMS

Premier Hydrologic Model Today (HEC)

Performs RF-RO Calculations for Watersheds

Basic Input and Output Options Precipitation Options Unit Hydrograph Options Flood Routing Option Creating and Viewing Results and Graphs

Execution of HEC-HMS

Running actual projects

Calibration to gage data

Castro Valley case study

Keegans example

Linkage with GIS/NEXRAD data (HEC Geo-

HMS)

The Hydrologic Cycle

100Precipitation on land

InfiltrationWater table

Groundwater flow

1 Groundwaterdischarge

38 Surface discharge

61Evaporation from land

39Moisture over land

385Precipitation

on ocean

424Evaporationfrom ocean

Surfacerunoff

Imperviousstrata

GroundwaterRecharge

Precipitation

Snowmelt

Uses of the HEC Program

Models the rainfall-runoff process in a watershed

based on watershed physiographic data

Offers a variety of modeling options in order to compute UH for basin areas.

Offers a variety of options for flood routing along streams.

Capable of estimating parameters for calibration of each basin based on comparison of computed data to observed data

HEC-1 Program History

HEC-1 - History of Model Development

Separate Programs: 1967 by Leo R. Beard

Major Revision and Unification: 1973 Second Major Revision: 1981 (Dam Breach, Kinematic Wave)

PC Versions: 1984 (partial), 1988 (full)

HEC-1/HMS Program History

Current Versions: 1991, 1998 1991 Version Provides Extended Memory Support

1998 Version 4.1 is Final Release

HEC “NexGen” Project Begins 1990 (RAS, HMS, FDA)

HEC-HMS - New GUI and Updates First Release April 1998 Version 1.1 Released April 1999 Current Version 2.0.3

HEC-HMS BackgroundPurpose of HEC-HMS

Improved User Interface, Graphics, and Reporting

Improved Hydrologic Computations Integration of Related Hydrologic Capabilities

Importance of HEC-HMS Foundation for Future Hydrologic Software Replacement for HEC-1

Improvements over HEC-1Ease of Use

projects divided into three components user can run projects with different parameters instead of creating new projects

hydrologic data stored as DSS files capable of handling NEXRAD-rainfall data and gridded precipitation

Converts HEC-1 files into HMS files

HEC-HMS Availability

Available Through HEC VendorsAvailable at HEC Web Site:http://www.wrc-hec.usace.army.mil“Public Domain” Program

No Copyright on SoftwareNo Copyright on HEC Documentation

Special Training Available

EXAMPLE 5.1

Small Watershed Example (HEC-1)

A small undeveloped watershed has the parameters listed in the following tables. A unithydrograph and Muskingum routing coefficients are known for subbasin 3, shown in Fig.E5.1(a). TC and R values for subbasins 1 and 2 and associated SCS curve numbers (CN)are provided as shown. A 5-hr rainfall hyetograph in in./hr is shown in Fig. E5.1(b) for astorm event that occurred on June 19, 1983. Assume that the rain fell uniformly over thewatershed. Use the information given to develop a HEC-1 input data set to model thisstorm. Run the model to determine the predicted outflow at point B. Note that this samesample will be used later with HEC-HMS as Example 5.2.

SUBBASINNUMBER

TC(hr)

R(hr)

SCS CURVENUMBER

% IMPERVIOUS(%)

AREA(mi2)

1 2.5 5.5 66 0 2.52 2.8 7.5 58 0 2.73 -- -- 58 0 3.3

TIME (hr) 0 1 2 3 4 5 6 7UH FORSUBBASIN 3:

U (cfs) 0 200 400 600 450 300 150 0

Muskingum coefficients: x = 0.15, K = 3 hr, Area = 3.3 sq mi

ID ****ID ****ID ****ID ****IT 60 60 19-Jun-83 1200 100IO 4KK SUB1KMPI 0.2 1.5 2 1 0.5BA 2.5LS 66 0UC 2.5 5.5KK SUB2KMBA 2.7LS 58 0UC 2.8 7.5KK AKMHC 2

KMRM 1 3 0.15KK SUB3KMBA 3.3LS 58 0UI 0 200 400 600 450 300 150 0KK BKMHC 2ZZ

MUSKINGUM ROUTING FROM A TO B

RUNOFF FROM SUBBASIN 3

COMBINE FLOW FROM SUB 3 AND ROUTED TO POINT B

KKA TO B

EXAMPLE 5.1

HEC-1 INPUT DATA SET

RUNOFF FROM SUBBASIN 1

RUNOFF FROM SUBBASIN 2

COMBINE RUNOFF FROM SUB 1 WITH RUNOFF FROM SUB 2 AT A

Solution The input data set is as follows:

Program Organization

Main project screen Connects to all data and information through menus

Using HEC-HMS

Three components Basin model - contains the elements of the basin, their connectivity, and runoff parameters

Meteorologic Model - contains the rainfall and evapotranspiration data

Control Specifications - contains the start/stop timing and calculation intervals for the run

Project Definition May contain several basin models, meteorologic models, and control specifications

User can select a variety of combinations of the three models in order to see the effects of changing parameters on one subbasin

Basin ModelBasin Model

Based on Graphical User Interface (GUI)

Click on elements from left and drag into basin area

Can import map files from GIS programs to use as background

Actual locations of elements do not matter, just connectivity and runoff parameters

Basin Model Elements

subbasins- contains data for subbasins (losses, UH transform, and baseflow)

reaches- connects elements together and contains flood routing data

junctions- connection point between elements

reservoirs- stores runoff and releases runoff at a specified rate (storage-discharge relation)

Basin Model Elements

sinks- has an inflow but no outflow sources- has an outflow but no inflow

diversions- diverts a specified amount of runoff to an element based on a rating curve - used for detention storage elements or overflows

Basin Model Parameters

Loss rate, UH transform, and baseflow methods

Abstractions (Losses)

Interception Storage

Depression Storage

Surface Storage

Evaporation

Infiltration

Interflow

Groundwater and Base Flow

Loss Rate methods

Green & Ampt Initial & constant SCS curve no. Gridded SCS curve no. Deficit/Constant No loss rate

Initial and Uniform Loss Computation

Initial Loss Applied at Beginning of Storm Estimated from Previous or SCS data Sand: 0.80-1.50 inches; Clay: 0.40-1.00 inches

Uniform Loss Applied Throughout Storm Also Estimated From Previous Studies or SCS Data

Sand: 0.10-0.0 in/hr; Clay 0.05-0.15 in/hr

HEC-HMS Loss Entry Window

Rainfall/Runoff Transformation Unit Hydrograph Distributed Runoff Grid-Based Transformation Methods:

Clark Snyder SCS Input Ordinates ModClark Kinematic Wave

Unit Hydrograph

Definition: Sub-Basin Surface Outflow Due to Unit (1-in) Rainfall Excess Applied Uniformly Over a Sub-Basin in a Specified Time Duration

Duration of UH: HEC-HMS Sets Duration Equal to Computation Interval

Synthetic Unit Hydrographs

Computed from Basin CharacteristicsHEC- HMS Synthetic Unit Hydrographs

SCS Dimensionless Unit graph Clark Unit Hydrograph (TC & R) Snyder Unit Hydrograph User-Defined Input Unit Hydrograph ModClark Unit Hydrograph

Clark Unit Hydrograph Computation

Estimating Time of Concentrationfor Clark Unit HydrographHydraulic Analysis Method

Compute Travel Time in Open Channels and Storm Sewers based on Flow Velocities

Compute Reservoir Travel Time from Wave Velocity

Overland Flow Equations Kerby Method Kirpich Method Overton & Meadows SCS TR-55 Method for Shallow Concentrated Flow

Baseflow Options

recession constant monthly

linear reservoir

no baseflow

Stream Flow Routing

Simulates Movement of Flood Wave Through Stream Reach

Accounts for Storage and Flow Resistance

Allows modeling of a watershed with sub-basins

Reach Routing

Flood routing methods:

Simple Lag

Modified Puls

Muskingum

Muskingum Cunge

Kinematic Wave

HEC-HMS Methods forStream Flow Routing

Hydraulic Methods - Uses partial form of St Venant Equations Kinematic Wave Method Muskingum-Cunge Method

Hydrologic Methods Muskingum Method Storage Method (Modified Puls) Lag Method

Effects of Stream Flow Routing

Storage S

t

Outflow

Inflow

Avg Inflow - Avg Outflow = dS/dt

Modified Puls (Storage)Stream Flow Routing Method

Storage-Indication Relationship:

I1 + I2 + (2S1/t - Q1)= (2S2/t + Q2)

I - Q = (dS/dt)

Averaging at two points in time: 1 and 2

HEC-HMS Stream Flow RoutingData Window

Storage-Discharge Relationships

Stream Flow Diversions

Diversion IdentificationMaximum Volume of Diversion (Optional)

Maximum Rate of Diversion (Optional)Diversion Rating Table

Stream Flow Rates Upstream of Diversion

Corresponding Diversion Rates

Stream Flow DiversionsFlow is allowed to move from one channel

to another via a side weir or flow across a low divide Weir

Flow increases until a fixed level and then a flow diversion table determines rate throughthe weir or across the divide

Diverted Q

Reservoir Routing

Developed Outside HEC-HMS

Storage Specification Alternatives:Storage versus DischargeStorage versus ElevationSurface Area versus Elevation

Discharge Specification Alternatives:Spillways, Low-Level Outlets, PumpsDam Safety: Embankment Overflow, Dam Breach

Reservoirs

Q (cfs)

I=Q

time

Q (cfs)

Inflow

Outflow

I - Q = dSdt

Level Pool ReservoirQ (weir flow)

Q (orifice flow)

I

SH

S = f(Q) Q = f(H)

Orifice flow:

Q = C * 2gH

Q

I

I

Weir Flow: Q = CLH3/2

Q

Pond storage with outflow pipe

Orifice flow

Weir flows

Inflow and Outflow

Reservoir Data Input

Initial Conditions to Be Considered Inflow = Outflow Initial Storage Values Initial Outflow Initial Elevation

Elevation Data Relates to Both Storage/Area and Discharge

HEC-1 Routing Routines with Initial Conditions and Elevation Data can be Imported as Reservoir Elements

Reservoir Data Input Window

Meteorologic ModelMeteorologic Model

Precipitation user hyetograph

user gage weighting

inverse-distance gage weighting

gridded precipitation

frequency storm

standard project storm - Eastern U.S.

Evapotranspiration-ET

monthly average, no evapotranspiration

Precipitation

Historical Rainfall DataRecording GagesNon-Recording Rainfall Gages

Design StormsHypothetical Frequency StormsCorps Standard Project StormProbable Maximum Precipitation

Gage Data

Gage Data (from project definition screen)

Precipitation gages- precipitation data for use with meteorologic models

Stream gages-

observed level data to compare computed and actual results

Precipitation: Gridded Weather Radar DataData from National Weather Service

NexRAD program, Doppler Radar

Data must be manipulated and stored in DSS file format

Grids are HRAP (NWS) or SHG (HEC)HRAP uses spherical projections and generalized earth radius valuesSHG uses Albers Equal Area projectionsGrids cover about 1 square kilometer

Historical raw data may not be archived

Sources of Rainfall Intensity-Duration-Frequency (IDF)

East of 105th Meridian (Denver) NWS HYDRO-5 (5 minutes to 60 minutes) NWS TP-40 (2 hours to 24 hours) - 1961 NWS TP-49 (2 days to 10 days)

West of 105th Meridian NOAA Atlas 2 (Separate Volumes for Each State)

Input and Output Files

project-name.HMS: List of models, descriptions and project default method options

basin-model-name.BASIN: Basin model data, including connectivity information

precipitation-model-name.PRECIP: Precipitation model data

control-specifications- name.CONTROL: Control specifications

run-name.LOG: Messages generated during execution of run

project-name.RUN: List of runs, including most recent execution time

Input and Output Files

project-name.DSS: DSS file containing basin model data such as computed hydrographs and storage discharge relationships

project-name.DSC: List of files contained in DSS file

project-name.OUT: Log of operations for the DSS file

project-name.MAP: Coordinate point file for subbasin boundaries and channel location

project-name.GAGE: Listing of gages available for use in the project

HMStemp.TMP: Echo listing of imported HEC-1 model

Data Storage System (DSS)Multiple time series or relational data setsEach data set or record has a unique

pathname/Castro Valley/Fire Dept/PRECIP-INC/16Jan197/10min/Obs/

Pathnames Consist of Parts A through F Part A: General name, project name Part B: Specific name, or control point Part C: Data type (PRECIP-INC, PRECIP-CUM, FLOW, STORAGE, etc.)

Part D: Start Date Part E: Time interval Part F: User specified

The HEC-HMS “Options”

Precipitation Option (6 available)Loss Computation (5 available)Runoff Transform Computation (6 available)

Routing Computation (7 available)Over 6 x 5 x 6 x 7 = 1,260 Combinations

Subbasin

routing reach

Control SpecificationsControl Specifications - Start/Stop/Time Interval

Running a project

User selects the

1. Basin model

2. Meteorologic model

3. Control ID for the HMS run

Viewing Results

To view the results: right-click on any basin element, results will be for that point

Display of results: hydrograph- graphs outflow vs. time summary table- gives the peak flow and time of peak

time-series table- tabular form of outflow vs. time

Comparing computed and actual results: plot observed data on the same hydrograph to by selecting a discharge gage for an element

Viewing Results

hydrograph

HEC-HMS Output1. Tables

SummaryDetailed (Time Series)

2. Hyetograph Plots3. Sub-Basin Hydrograph Plots4. Routed Hydrograph Plots5. Combined Hydrograph Plots6. Recorded Hydrographs - comparison

Viewing Results

Summary table

Time series table

HEC-HMS Output

Sub-Basin PlotsRunoff Hydrograph

HyetographAbstractionsBase Flow

HEC-HMS Output

Junction PlotsTributary Hydrographs

Combined Hydrograph

Recorded Hydrograph

Purpose of Calibration

Can Compute Sub-Basin ParametersLoss Function ParametersUnit Hydrograph Parameters

Can Compute Stream Flow Routing Parameters

Requires Gage Records

FINALLY - information on HEC-HMS

www.hec.usace.army.mil/software/software_distrib/hec-hms/hechmsprogram.html(the user’s manual can be downloaded from this site)

www.dodson-hydro.com/download.htm# Electronic_Documents

Available on the laboratory computers