HEC-HMS

The 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

P r e 1 c 0 0 t i o n o n l a n 39 61 Evaporation from land Snow melt Surface runoff Precipitation Infiltration Groundwater Recharge Water t able Groundwater flow Impervious strata 385 Precipitation on ocean 424 Evaporation from ocean 38 Surface discharge 1 Groundwater discharge

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 Background

Purpose 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-1

Ease 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 Vendors Available at HEC Web Site: http://www.wrc-hec.usace.army.mil

“Public Domain” Program No Copyright on Software No Copyright on HEC Documentation Special Training Available

EXAMPLE 5.1

Small Wat ershed Exa mple (HEC-1)

A small und eveloped watershed has the p arameters li sted in the following tables. A un it hyd rograph and Muskingu m r out ing coefficients are known fo r subba sin 3, sho wn in Fig.

E5.1(a).

TC

and

R

values for subba sins 1 and 2 and associated SCS curve nu mbers (CN) are provided as shown . A 5-hr rainfa ll hye togr aph in in./hr is shown in Fig. E5.1(b) for a storm even t that occurred on June 19, 1983. Assume that the rain fell uniforml y ove r the watershed. Use the information g iven to deve lop a HEC-1 input data set to model t his storm. Run the model t o determi ne the predicted outflow at point

B

. Note that this same sample will be used later with HEC-HMS as Exa mple 5.2.

SUBBASIN NUMBER

1 2 3

TC

(hr)

2.5

2.8

--

R

(hr)

5.5

7.5

--

SCS CURVE NUMBER

66 58 58

% IMPERVIOUS (%)

0 0 0

AREA (mi 2 )

2.5

2.7

3.3

UH FOR SUBBAS IN 3: TIME (hr) U (cfs)

0 0 1 200 2 400 3 600 4 450 5 300 6 150 7 0

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

Solution

The input data set is as follows: ID ID ID **** **** ****

EXAMPLE 5.1

HEC-1 INPUT DATA SET

ID IT IO KK KM **** 60 4 SUB1 60 19-Jun-83 1200 100 PI BA LS UC KK KM 0.2

2.5

2.5

SUB2 RUNOFF FROM SUBBASIN 1 1.5

66 5.5

2 0 1 0.5

RUNOFF FROM SUBBASIN 2 RM KK KM BA LS UI KK KM HC ZZ BA LS UC KK KM HC KKA TO B KM 2.7

2.8

A 2 58 7.5

0 COMBINE RUNOFF FROM SUB 1 WITH RUNOFF FROM SUB 2 AT A 1 SUB3 MUSKINGUM ROUTING FROM A TO B 3 0.15

3.3

0 B 2 RUNOFF FROM SUBBASIN 3 58 200 0 400 600 450 COMBINE FLOW FROM SUB 3 AND ROUTED TO POINT B 300 150 0

Program Organization

Main project screen  Connects to all data and information through menus

Using HEC-HMS

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

Basin 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 Characteristics HEC- 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 Concentration for Clark Unit Hydrograph

Hydraulic 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 for Stream 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

Avg Inflow - Avg Outflow = dS/dt Inflow  Storage S D t Outflow

Modified Puls (Storage) Stream Flow Routing Method

Storage-Indication Relationship:

I - Q = (dS/

d

t) Averaging at two points in time: 1 and 2 I 1 + I 2 + (2S 1 / D t - Q 1 )= (2S 2 / D t + Q 2 )

HEC-HMS Stream Flow Routing Data Window

Storage-Discharge Relationships

Stream Flow Diversions

Diversion Identification Maximum Volume of Diversion (Optional) Maximum Rate of Diversion (Optional) Diversion Rating Table  Stream Flow Rates Upstream of Diversion  Corresponding Diversion Rates

Stream Flow Diversions

Flow is allowed to move from one channel to another via a side weir or flow across a low divide Weir Diverted Q Flow increases until a fixed level and then a flow diversion table determines rate through the weir or across the divide

Reservoir Routing

Developed Outside HEC-HMS Storage Specification Alternatives: Storage versus Discharge Storage versus Elevation Surface Area versus Elevation Discharge Specification Alternatives: Spillways, Low-Level Outlets, Pumps Dam Safety: Embankment Overflow, Dam Breach

Reservoirs

Pond storage with outflow pipe Orifice flow Weir flows Inflow and Outflow

I - Q = dS dt I I S Level Pool Reservoir Q (weir flow) H S = f(Q) Q = f(H) Q (orifice flow) Orifice flow: Q = C * 2gH Q I Weir Flow: Q = CLH 3/2 Q Inflow I=Q Outflow time

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 Model

Meteorologic 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 Data Recording Gages Non-Recording Rainfall Gages Design Storms Hypothetical Frequency Storms Corps Standard Project Storm Probable 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 Data

Data 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 values SHG uses Albers Equal Area projections Grids 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-nam e.HMS:

List of models, descriptions and project default method options

basin-model-nam e.BASIN:

Basin model data, including connectivity information

precipitation-model-nam e.PRECIP:

model data Precipitation

control-specifications- nam e.CONTROL:

specifications

run-nam e.LOG:

of run Control Messages generated during execution

project-nam e.RUN:

List of runs, including most recent execution time

Input and Output Files

project-name .DSS:

data such as computed hydrographs and storage discharge relationships DSS file containing basin model

project-name .DSC: project-name .OUT:

List of files contained in DSS file Log of operations for the DSS file

project-name .MAP:

Coordinate point file for subbasin boundaries and channel location

project-name .GAGE:

in the project Listing of gages available for use

HMStemp.TMP:

Echo listing of imported HEC-1 model

Data Storage System (DSS) Multiple time series or relational data sets Each 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 Specifications

Control 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

1.

2.

3.

4.

5.

6.

HEC-HMS Output

Tables Summary Detailed (Time Series) Hyetograph Plots Sub-Basin Hydrograph Plots Routed Hydrograph Plots Combined Hydrograph Plots Recorded Hydrographs - comparison

Viewing Results

Summary table Time series table

HEC-HMS Output

Sub-Basin Plots Runoff Hydrograph Hyetograph Abstractions Base Flow

HEC-HMS Output

Junction Plots Tributary Hydrographs Combined Hydrograph Recorded Hydrograph

Purpose of Calibration

Can Compute Sub-Basin Parameters Loss Function Parameters Unit Hydrograph Parameters Can Compute Stream Flow Routing Parameters Requires Gage Records

FINALLY - information on HEC-HMS

www.hec.usace.army.mil/software/software_d istrib/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