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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