Short Name:
Short name of model
Short name of model
HEC-HMS
Long Name:
Long name of model
Long name of model
Hydrologic Modeling System
Model Type:
Event and continuous; distributed, semi-distributed, and lumped.
Event and continuous; distributed, semi-distributed, and lumped.
Event or continuous in time; distributed, semi-distributed, or lumped in space
Flood Mechanism:
Riverine flood or urban flood or rural flash flood or urban flash flood; rainfall-only or rainfall-snowmelt derived; note wildfire/debris-flow applicability where relevant
Riverine flood or urban flood or rural flash flood or urban flash flood; rainfall-only or rainfall-snowmelt derived; note wildfire/debris-flow applicability where relevant
Pluvial, fluvial flooding, rainfall-only, and/or rainfall-snowmelt flooding, supports post‑wildfire runoff response (burned watersheds) and debris‑flow triggering assessments (via sediment/debris workflows)
Usage:
Demonstrated application purposes with emphasis on flash flood and riverine flood forecasting; include wildfire/debris use-cases where applicable
Demonstrated application purposes with emphasis on flash flood and riverine flood forecasting; include wildfire/debris use-cases where applicable
Short to medium range flow forecasting, flood damage reduction studies, flow frequency studies, reservoir spillway studies, reservoir dam failure studies, water availability assessment, and post‑wildfire hydrology screening and watershed sediment/debris hazard analyses
Special Features:
Unique flood mechanisms, unique usage, additional special simulation purposes
Unique flood mechanisms, unique usage, additional special simulation purposes
Geographical Information System (GIS) capabilities, Graphical User Interface (GUI) for visualization of inputs and outputs, multiple input and output data formats, numerous modeling methods to represent meteorological and land surface processes, and multiple compute types ranging from simple (e.g., Simulation Run) to complex (e.g., Ensemble Analysis, Stochastic Storm Transposition, Uncertainty Analysis, Sediment Analysis). Added tools to easily import and manipulate outside data sources and directly used for an analysis (i.e. Gridded Data, NOAA Atlas 14 grids, USGS gages). Post‑wildfire workflows supported through rapid parameter changes (loss/transform/surface) and sediment/debris modules.
Background:
Description of model history and background
Description of model history and background
HEC-HMS is designed to simulate the complete hydrologic processes of dendritic watershed systems. It includes many traditional hydrologic analysis procedures such as event infiltration, unit hydrographs, and hydrologic routing. It also includes procedures for continuous simulation with evapotranspiration, snowmelt, and soil moisture accounting. Gridded analysis is supported with gridded atmospheric components, gridded homogeneous or heterogeneous infiltration parameters. Supplemental tools are included for parameter estimation (optimization), uncertainty analysis (Monte Carlo), flow forecasting, depth-area analysis, and sediment/debris analysis. The first version was released in 1998. The current version (v4.13) was released in 2025.
Channel Routing:
Available methods for flood wave routing
Available methods for flood wave routing
Kinematic wave, Lag, Lag and K, Modified Puls, Muskingum, Muskingum-Cunge, Normal Depth, and Straddle Stagger. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/reach-elements/selecting-a-reach-routing-method.
Available methods for sediment/debris routing and related sediment transport computations (as implemented in HMS Sediment Analysis)
- Sediment Transport Potential Functions: Ackers-Wights, Engelund-Hansen, Laursen-Copeland, Meyer-Peter Muller, Toffaleti, Wilcock, Yang, Krone Parthenaides, and Sediment Delivery Ratio. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/erosion-and-sediment-transport/watershed-sediment-properties.
- Sediment Routing Methods: Linear Reservoir, Muskingum, Uniform Equilibrium and Volume Ratio. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/erosion-and-sediment-transport/reach-sediment.
Reservoir Operation:
Available methods for reservoir routing and gate control operations if any
Available methods for reservoir routing and gate control operations if any
Outflow Curve, Specified Release, Outflow Structures, and Rule-Based Operations. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/reservoir-elements.
Available methods for reservoir sediment routing / trapping and operational impacts (where configured)
- Sediment Trap Method: Complete Sediment Trap, Specified Sediment, Chen Sediment Trap, Brune Sediment Trap, and Zero Sediment Trap. For more information, see “https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/erosion-and-sediment-transport/reservoir-sediment”.
Surface Erosion:
Available methods for surface erosion
Available methods for surface erosion
Build-up Wash-off, Modified USLE, 2D Sediment Transport, Los Angeles Debris Methods, Multi-Sequence Debris Prediction Method, USGS Long-Term Debris Model, and USGS Emergency Assessment Debris Model. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/erosion-and-sediment-transport/subbasin-sediment.
Shortwave Radiation:
Available methods for shortwave radiation
Available methods for shortwave radiation
Bristow Campbell, FAO56, Gridded Gridded Hargreaves, Hargreaves, Specified Pyranograph, Interpolated Shortwave, and Reduced Solar Constant. For more information, see: https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/meteorology-description/shortwave-radiation.
Longwave Radiation:
Available methods for longwave radiation
Available methods for longwave radiation
FAO56, Gridded Longwave, Satterlund, Specified Pyrgeograph, Interpolated Longwave, and Stefan Boltzmann Longwave. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/meteorology-description/longwave-radiation.
Precipitation:
Available methods for precipitation
Available methods for precipitation
Frequency Storm, Gage Weights, Gridded Precipitation, HMR52 Storm, Interpolated Precipitation, Inverse Distance, Hypothetical Storm, Specified Hyetograph, MetSim Precipitation, and Standard Project Storm. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/meteorology-description/precipitation.
Temperature:
Gridded Temperature, Interpolated Temperature, MetSim Temperature, and Specified Thermograph. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/meteorology-description/temperature.
Windspeed:
Gridded Windspeed, Interpolated Windspeed, and Specified Anemograph. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/meteorology-description/windspeed.
Pressure:
Gridded Pressure, Specified Barograph, Interpolated Pressure, and Barometric Pressure. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/meteorology-description/pressure.
Dew Point:
Gridded Dew Point Temperature, Gridded Humidity, Interpolated Dew Point Temperature, Interpolated Humidity, Specified Dew Point Thermograph, Specified Humidograph, and Precipitation Index Humidity. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/meteorology-description/dew-point.
Evapotranspiration:
Available methods for potential evapotranspiration
Available methods for potential evapotranspiration
Annual Evapotranspiration, Gridded Hamon, Gridded Hargreaves, Gridded Penman Monteith, Gridded Priestley Taylor, Hamon, Hargreaves, Monthly Average, Penman Monteith, Priestley Taylor, and Specified Evapotranspiration. Potential evapotranspiration is used with a canopy that includes interception, crop coefficient, and soil moisture extraction. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/meteorology-description/evapotranspiration.
Discretization:
Defines how a subbasin is discretized (i.e., grid cells, lumped, etc.)
Defines how a subbasin is discretized (i.e., grid cells, lumped, etc.)
None, Structured, Unstructured, and File-Specified. The Discretization Method defines how a subbasin is discretized (i.e., grid cells, lumped, etc). For more information, see “https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/subbasin-elements/selecting-a-discretization-method.
Canopy:
Canopy methods are intended to represent plants that may intercept and store precipitation as well as extract water from the surface or soil.
Canopy methods are intended to represent plants that may intercept and store precipitation as well as extract water from the surface or soil.
Dynamic Canopy, Gridded Simple Canopy, and Simple Canopy. Canopy methods are intended to represent plants that may intercept and store precipitation as well as extract water from the surface or soil. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/subbasin-elements/selecting-a-canopy-method.
Snowmelt:
Available methods for snow accumulation and melt
Available methods for snow accumulation and melt
Gridded Temperature Index, Temperature Index, Gridded Hybrid, Gridded Energy Balance, and Energy Balance. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/subbasin-elements/selecting-a-snowmelt-method.
Infiltration:
Available methods for infiltration
Available methods for infiltration
Deficit and constant, exponential, Green and Ampt, gridded deficit and constant, gridded green and Ampt, gridded SCS curve number, gridded soil moisture accounting, initial and constant, layered Green and Ampt, SCS curve number, Smith and Parlange, and soil moisture accounting.
Surface Runoff Transform:
Available methods for surface runoff
Available methods for surface runoff
Clark Unit Hydrograph, Kinematic Wave, ModClark, SCS Unit Hydrograph, Snyder Unit Hydrograph, User-Specified S-Graph, User-Specified Unit Hydrograph, and 2D Diffusion Wave. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/subbasin-elements/selecting-a-transform-method.
Surface:
Available methods for surface runoff.
Available methods for surface runoff.
Gridded Simple Surface, Simple Surface, Dynamic Surface (designed for Post-Wildfire long-term hydrology), and Gridded Dynamic Surface. Surface methods are intended to represent the ground surface where water may accumulate in surface depression storage. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/subbasin-elements/selecting-a-surface-method.
Interflow:
Available methods for subsurface interflow
Available methods for subsurface interflow
Bounded Recession, Constant Monthly, Linear Reservoir, Nonlinear Boussinesq, and Recession Baseflow. Subsurface calculations are performed by a Baseflow Method contained within the subbasin. The Linear Reservoir method allows users to explicitly differentiate between interflow and baseflow. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/subbasin-elements/selecting-a-baseflow-method.
Available methods for percolation to groundwater
See the Infiltration row above. All infiltration methods allow for percolation to a baseflow method.
Input Data:
What types of input data are required for the model
What types of input data are required for the model
Precipitation at a minimum. Air temperature for snowmelt. Some methods may require additional boundary conditions (e.g., shortwave/longwave radiatioon, atmospheric pressure, windspeed, and/or relative humidity or dew point temperature).
Input Format:
What file formats can be used for input data
What file formats can be used for input data
Gridded data can be imported in NetCDF, GRIB, GeoTIFF, HDF, ASCII, BIL, and HEC-DSS formats, amongst others. Time series can be imported in text and/or HEC-DSS formats. For more information regarding data formats, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/shared-component-data. For more information regarding gridded data usage, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsguides/working-with-gridded-boundary-condition-data.
Input Time Interval:
What time interval is required for input data, and how are daily values utilized
What time interval is required for input data, and how are daily values utilized
Options range from 1 minute to daily, with automatic linear interpolation to the simulation time interval.
Optimization:
What tools are available for calibration and optimization
What tools are available for calibration and optimization
Multiple optimization algorithms (deterministic and stochastic) are available for estimating parameters using observed flow data. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/model-optimization.
Data Assimilation:
Can observed flow and previous forecast flow be used to update the forecast flow
Can observed flow and previous forecast flow be used to update the forecast flow
Observed data (e.g., flow, stage, etc) can be used to update model results. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/forecasting-streamflow.
Ensemble:
Can ensemble meteorologic forecasts be used in the model What tools are available for calibration and optimization
Can ensemble meteorologic forecasts be used in the model What tools are available for calibration and optimization
The Ensemble Analysis within HEC-HMS allows for mutiple base models to be created and simulated in a collective fashion to predict an outcome. Ensemble meteorologic forecasts can be incorporated within this analysis framework. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/ensemble-simulations.
Uncertainty:
How is uncertainty represented in the outputs
How is uncertainty represented in the outputs
A Monte Carlo uncertainty tool is available and integrated in the model. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/assessing-model-uncertainty.
Simulation Time Interval:
What time interval is used for simulation
Options range from 1 minute daily.
Model Output Time-Series: Both time series and gridded data output can be saved and visualized within HEC-HMS. Flow is available at all elements. Additional types of data are available depending upon selected methods. For more information regarding time series outputs, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/hydrologic-simulation/viewing-results-for-the-current-run. For more information regarding gridded outputs, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/hydrologic-simulation/viewing-spatial-results.
Time-Series Format:
What is the file format for output time-series data
What is the file format for output time-series data
HEC-DSS file format, programming API available.
Model Output Statistics:
What types of output statistics are available
What types of output statistics are available
Minima, maxima, and volumes necessary for showing mass balance are available at all elements. If observed data is specified at an element, goodness-of-fit statistics are also available.
Statistics Format:
What is the file format for output statistics data
What is the file format for output statistics data
Extensible Markup Language (XML)
Inventory Platform:
Platforms from this inventory in which this model can be integrated
Platforms from this inventory in which this model can be integrated
HEC-Real Time Simulation (HEC-RTS)
Additional Platform:
Additional platforms outside this inventory in which this model can be integrated
Additional platforms outside this inventory in which this model can be integrated
HEC-WAT
Installation:
Difficulty level for installation and configuration
Difficulty level for installation and configuration
Easy – Automatic installation package and portable version that does not require administrative privileges to download or use.
User Education:
Education level recommended for users
Education level recommended for users
BSc
Degree of Difficulty:
Score from 1 (difficult) to 5 (easy) rating the overall difficulty of use
Score from 1 (difficult) to 5 (easy) rating the overall difficulty of use
3
GIS Support:
How much GIS support is included for watershed delineation and parameter estimation
How much GIS support is included for watershed delineation and parameter estimation
GIS watershed delineation and parameter estimation tools are included. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/geographic-information.
Data Preparation:
What tools are included for importing and preparing time-series data
What tools are included for importing and preparing time-series data
Manual entry or external entry with HEC-DSSVue
Land Surface Parameters:
Parameters for infiltration, surface runoff, baseflow for each catchment
Parameters for infiltration, surface runoff, baseflow for each catchment
9 to 27, depending on user choices
Parameter Estimation:
What tools are included for estimating model parameters from physical data
What tools are included for estimating model parameters from physical data
Some parameters can be automatically estimated from GIS data. For more information, see https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.13/geographic-information/parameter-estimation.
Model Calibration:
What tools are included for model calibration
What tools are included for model calibration
Manual adjustment sliders, automatic optimization, graphs of observed and simulated results, goodness-of-fit indices
Model Verification:
What tools are included for model verification
What tools are included for model verification
Nash-Sutcliffe Efficiency, Modified Kling-Gupta Efficiency, Root Mean Squared Error Ratio, and Percent Bias at all elements with observed data.
Hardware Requirements:
Minimum hardware requirements
Minimum hardware requirements
PC with multi-core processor
Operating System:
Operating system – MS Windows, LINUX
Operating system – MS Windows, LINUX
Windows, macOS, Ubuntu Linux
Language of Core Code:
Programming language used for the core code (e.g. Fortran, C++, Java). If workflow scripting is supported (e.g. Python) then please specify
Programming language used for the core code (e.g. Fortran, C++, Java). If workflow scripting is supported (e.g. Python) then please specify
Java
Open Source:
Open source or closed source
Open source or closed source
No
Last Update and Version:
Date of latest update and the version number for the release
Date of latest update and the version number for the release
7/1/2025 (Version 4.13)
Next Update and Version:
Date of next planned update and the version number for the release
Date of next planned update and the version number for the release
Tentatively mid CY2026 (Version 4.14)
Active Development Community:
Is there an active developer community with regular updates and new releases?
Is there an active developer community with regular updates and new releases?
Yes
Platform integration:
Platforms in the inventory which integrate this model
Platforms in the inventory which integrate this model
HEC-RTS, HEC-RAS, HEC-ResSim
Download URL:
URL that can be used to download the software
URL that can be used to download the software
Free to Download and Use:
Is the software free to download and use?
Is the software free to download and use?
Yes, no registration required
Language of Software Interface:
Languages used for the software user interface
Languages used for the software user interface
English though multiple languages supported
Online Support URL:
URL that can be used to get online support
URL that can be used to get online support
https://www.hec.usace.army.mil/software/support_policy.aspx Limited support for non-USACE
Training Material URL (including example data sets):
URL that can be used to access training material
URL that can be used to access training material
Language of Trainings:
Languages used for the training material
Languages used for the training material
English
Guidance Material URL (including case studies and benchmarking of performance/speed):
URL for case studies and examples of its use. Ideally including benchmarking of performance
URL for case studies and examples of its use. Ideally including benchmarking of performance
Language of Guidance:
Languages used for the guidance material
Languages used for the guidance material
English
References:
Reference from scientific journals or publications
Reference from scientific journals or publications
Chu, S. and A. Steinman (2009) “Event and Continuous Hydrologic Modeling with HEC-HMS.” J. Irrigation and Drainage Engineering, vol 135, no 1, pp 119-124. Google Scholar currently lists 9,770 journal articles, proceedings, reports, manuals, and other documents.
Owner, Developer:
Contact organization for the software. Could be core developer
Contact organization for the software. Could be core developer
US Army Corps of Engineers
https://www.hec.usace.army.mil
Mailing Address:
Department of The Army
Corps of Engineers
Institute for Water Resources
Hydrologic Engineering Center
609 Second Street
Davis, CA 95616-4687
HEC Phone: +1 530.756.1104
HEC Fax: +1 530.756.8250