Engineers, surveyors, floodplain managers and FEMA mapping partners will benefit in viewing this page to understand the current nationally accepted hydrologic models that meet National Flood Insurance Program (NFIP) minimum requirements for flood hazard mapping.
Disclaimers
- This website lists models, where the compliance with the requirements of 44 CFR 65.6(a)(6) has been previously demonstrated for use in FEMA flood hazard studies and/or mapping efforts. The lists include models that professional engineers can use to perform engineering analysis and mapping for flood insurance studies, however a model’s inclusion on this list does not indicate whether its approval or certification is current as to any other governmental agency. Professional engineers are ultimately responsible for the appropriate application and accuracy of the results.
- FEMA is not responsible for technical support or accuracy of the results and has not evaluated the technical soundness of the models independently.
- This list cannot be used as a marketing tool explicitly or implicitly anywhere.
- FEMA updates its list as necessary, however, the accuracy of this list is not guaranteed. It is highly recommended that model selection is discussed with FEMA before undertaking or initiating any analysis intended to be submitted to FEMA.
- FEMA provides this list for reference only and, in doing so, does not endorse any non-federal products, companies or services. If you believe that any information provided on this page is inaccurate, please contact FEMA at 1-877-FEMA MAP (1-877-336-2627).
Current Nationally Accepted Hydrologic Models
| PROGRAM | DEVELOPED BY | AVAILABLE FROM | COMMENTS | |
|---|---|---|---|---|
| Single Event | ||||
| HEC-1 4.0.1 and up 1 (May 1991) | U.S. Army Corps of Engineers | Water Resources Support Center Corps of Engineers Hydrologic Engineering Center (HEC) 609 Second Street Davis, CA 95616-4687 | Flood hydrographs at different locations along streams. Calibration runs preferred to determine model parameters. Public Domain: Yes | |
| HEC-HMS 1.1 and up (Mar 1998) | U.S. Army Corps of Engineers | U.S. Army Corps of Engineers Hydrologic Engineering Center 609 Second Street Davis, CA 95616-4687 | The Hydrologic Modeling System provides a variety of options for simulating precipitation-runoff processes. It now includes snowmelt and interior pond capabilities, plus enhanced reservoir options. Calibration runs should be used wherever possible to determine model parameters. Public Domain: Yes | |
| TR-20 Win 1.00 (Jan 2005) | U.S. Department of Agriculture, Natural Resources Conservation Service | U.S. Department of Agriculture, Natural Resources Conservation Service | The TR-20 computer model has been revised and completely rewritten as a Windows based program. It is storm event surface water hydrologic model applied at a watershed scale that can generate, route and combine hydrographs at points within a watershed. Calibration runs preferred to determine model parameters. Public Domain: Yes | |
| WinTR-55 1.0.08 (Jan 2005 ) | U.S. Department of Agriculture, Natural Resources Conservation Service | U.S. Department of Agriculture, Natural Resources Conservation Service | The new WinTR-55 uses the WinTR-20 program as the driving engine for analysis of the hydrology of the small watershed system being studied. Public Domain: Yes | |
| SWMM 5 Version 5.0.005 (May 2005) and up | U.S. Environmental Protection Agency | Water Supply and Water Resources Division U.S. Environmental Protection Agency | SWMM 5 provides an integrated environment for editing study area input data, running hydrologic simulations and viewing the results in a variety of formats. These include color-coded drainage area and conveyance system maps, time series graphs and tables, profile plots and statistical frequency analyses. Calibration or verification to the actual flood events highly recommended. Public Domain: Yes | |
| MIKE 11 (2009 SP4) | DHI Water and Environment | DHI, Inc. 319 SW Washington St. Suite 614 Portland, OR 97204 | Simulates flood hydrographs at different locations along streams using unit hydrograph techniques. Three methods are available for calculating infiltration losses and three methods for converting rainfall excess to runoff, including SCS Unit hydrograph method. Calibration or verification to the actual flood events highly recommended. Public Domain: No | |
| National Weather Service FLDWAV Computer Program | National Weather Service (NWS) | National Weather Service (NWS) | FLDWAV program, developed by the National Weather Service (NWS), is a generalized flood routing program with the capability to model floodflows through a single stream or a system of interconnected waterways. For more information this program, visit the National Weather Service FLDWAV Computer Program factsheet. | |
| PondPack v.8 (May 2002) and up | Bentley Systems | Bentley Systems 685 Stockton Drive Exton, PA 19341 | The program is for analyzing watershed networks and aiding in sizing detention or retention ponds. Only the NRCS Unit Hydrograph method and NRCS Tc calculation formulas are acceptable. Other hydrograph generation methods or Tc formulas approved by state agencies in charge of flood control or floodplain management are acceptable for use within the subject state. Calibration or verification to the actual flood events highly recommended. Public Domain: No | |
| XP-SWMM 8.52 and up | XP Solutions | XP Solutions 5415 SW Westgate Dr. Suite 150 Portland, OR 97221 | Model must be calibrated to observed flows, or discharge per unit area must be shown to be reasonable in comparison to nearby gage data, regression equations or other accepted standards for 1% annual chance events. Calibration or verification to the actual flood events highly recommended. Public Domain: No | |
| Xpstorm 10.0 (May 2006) | XP Solutions | XP Solutions 5415 SW Westgate Dr. Suite 150 Portland, OR 97221 | Xpstorm has the same stormwater modeling capability as the XP-SWMM program. Calibration or verification to the actual flood events highly recommended. | |
| Gridded Surface Subsurface Hydrologic Analysis (GSSHA) Version 1.43 and up (Sept. 2006) | USACE | US Army Engineering Research and Development Center, Coastal & Hydraulics Laboratory 3909 Halls Ferry Rd Vicksburg, MS 39180 | GSSHA is a spatially explicit, physics based hydrologic model that can simulate a wide range of runoff mechanisms, including infiltration-excess and saturation-excess runoff, snow melt, storm and tile drains, groundwater exfiltration and discharge, lakes (including non-draining lakes such as prairie potholes), detention basins, culverts and weirs. GSSHA also includes the ability to simulate time and space varying head boundary conditions, making it suitable in many coastal watershed applications. GSSHA has been applied from jungle rainforests to the permafrost basins of Alaska, from the desert southwest to the Florida Everglades as well as in urban storm surge flooding simulations in New Orleans and New York City. More information can be found on the GSSHA Wiki webpage Public Domain: Yes | |
| Continuous Simulation | ||||
| HSPF 10.10 and up (Dec 1993) | U.S. Environmental Protection Agency, U.S. Geological Survey | Center for Exposure Assessment Modeling U.S. Environmental Protection Agency Office of Research and Development Environmental Research Laboratory 960 College Station Road Athens, GA 30605-2720 | Calibration to actual flood events required. Water Resources Application Software Public Domain: Yes | |
| HEC-HMS 3.0 and up (Dec 2005) | U.S. Army Corps of Engineers | U.S. Army Corps of Engineers Hydrologic Engineering Center 609 Second Street Davis, CA 95616-4687 | The Hydrologic Modeling System (HMS) includes two different soil moisture models suitable for continuous modeling, one with five layers and one with a single layer. Two approaches to evapotranspiration are provided and snowmelt is available. Calibration to actual flood events is required. Public Domain: Yes | |
| MIKE 11 RR (2009 SP4) | DHI Water and Environment | DHI, Inc. 319 SW Washington St. Suite 614 Portland, OR 97204 | The Rainfall-Runoff Module is a lumped-parameter hydrologic model capable of continuously accounting for water storage in surface and sub-surface zones. Flood hydrographs are estimated at different locations along streams. Calibration to actual flood events is required. MIKE 11 River Modeling Public Domain: No | |
| PRMS Version 2.1 (Jan 1996) | U.S. Geological Survey | U.S. Geological Survey 12201 Sunshine Valley Drive Reston, VA 22092 U.S. Geological Survey P.O. Box 25046, Mail Stop 412 Denver Federal Center Lakewood, CO 80225-0046 | PRMS is a modular-designed, deterministic, distributed-parameter modeling system that can be used to estimate flood peaks and volumes for floodplain mapping studies. Calibration to actual flood events required. The program can be implemented within the Modular Modeling System that facilitates the user interface with PRMS, input and output of data, graphical display of the data and an interface with GIS. Public Domain: Yes | |
| Gridded Surface Subsurface Hydrologic Analysis (GSSHA) Version 1.43 and up (Sept. 2006) | USACE | US Army Engineering Research and Development Center, Coastal & Hydraulics Laboratory 3909 Halls Ferry Rd Vicksburg, MS 39180 | GSSHA is a spatially explicit, physics based hydrologic model that can simulate a wide range of runoff mechanisms, including infiltration-excess and saturation-excess runoff, snow melt, storm and tile drains, groundwater exfiltration and discharge, lakes (including non-draining lakes such as prairie potholes), detention basins, culverts and weirs. GSSHA also includes the ability to simulate time and space varying head boundary conditions, making it suitable in many coastal watershed applications. GSSHA has been applied from jungle rainforests to the permafrost basins of Alaska, from the desert southwest to the Florida Everglades as well as in urban storm surge flooding simulations in New Orleans and New York City. More information can be found on the GSSHA Wiki webpage Public Domain: Yes | |
1 The enhancement of the program in editing and graphical presentation can be obtained from several private companies.
Current Locally Accepted Hydrologic Models
Hydrologic Models: Determination of Flood Hydrographs
| PROGRAM | DEVELOPED BY | AVAILABLE FROM | COMMENTS |
|---|---|---|---|
| Single Event | |||
| VCRat 2.6 (Dec. 2008) | Ventura County Watershed Protection District | Ventura County Watershed Protection District 800 S. Victoria Ave., Ventura, CA 93009 | The VCRat model is based on the Modified Rational Method (MRM) and calculates a hydrograph of runoff at all subarea collection points within the watershed, combines hydrographs from each subarea, and routes the combined hydrograph through the channel system. Manual and the training materials are available from the District. Only accepted for usage within the Ventura County, California area. Public Domain: Yes. |
| AHYMO 97 (Aug. 1997) | Albuquerque Metropolitan Arroyo Flood Control Authority, Anderson-Hydro | Anderson-Hydro 13537 Terragon Drive, NE Albuquerque, NM 87112 | Flood hydrographs at different locations along streams. Only accepted for usage and the default parameters in the model applicable within New Mexico. Information on the AHYMO model Public Domain: Yes |
| Colorado Urban Hydrograph Procedure (CUHPF/PC) (May 1996 and May 2002) | Denver Urban Drainage and Flood Control District | Denver Urban Drainage and Flood Control District 2480 West 26th Avenue, Suite 156-B Denver, CO 80211 | Flood hydrographs at different locations along streams. Hydrographs are routed using UDSWM2-PC (a modified version of the Runoff Block of EPA's SWMM). Only accepted for usage and the default parameters in the model applicable within the Denver, Colorado, metro area. Public Domain: Yes |
| FLO-2D v. 2009. 06 | Jimmy S. O'Brien | FLO-2D Software, Inc. P.O. Box 66 Nutrioso, AZ 85932 | Runoff excess is computed by distributed hydrological parameters. Surface runoff routing is based on the non-linear dynamic wave approximation of the momentum equation. Applicable to watersheds with flows characterized as dispersed surface runoff instead of concentrated channel flow. |
| FLO-2D Pro | Jimmy S. O'Brien | P.O. Box 66 Nutrioso, AZ 85932 | An integrated river and floodplain model. A flood routing hydrologic and hydraulic model with urban detail features, sediment transport, mudflow, and groundwater modeling Please review 'Guidelines and Specifications for Flood Hazard Mapping Partners, Appendix G: Guidance for Alluvial Fan Flooding Analyses and Mapping (Feb 2002)' thoroughly before applying to alluvial fans. Coordination with the Regional Office is required. Calibration to actual flood events is required. Only accepted for usage within Mohave County, Pinal County, and Maricopa County, Arizona. Public Domain: No |
View More Nationally and Locally Accepted Models
Below are additional nationally and locally accepted models in the NFIP Program:
- Coastal Models Meeting the Minimum Requirement of NFIP
- Hydraulic Models Meeting the Minimum Requirement of NFIP
- Statistical Models Meeting the Minimum Requirement of NFIP
Numerical Models No Longer Accepted
Please visit the Numerical Models No Longer Accepted by FEMA for NFIP Usage page for a list of unaccepted models.
Last Updated:
09/12/2016 - 12:59