Hydrologic Models Meeting the Minimum Requirement of National Flood Insurance Program

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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

Hydrologic Models: Determination of Flood Hydrographs
PROGRAMDEVELOPED BYAVAILABLE FROMCOMMENTS
Single Event
HEC-1 4.0.1 and up 1
(May 1991)
U.S. Army Corps of EngineersWater 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 EngineersU.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 ServiceU.S. Department of Agriculture, Natural Resources Conservation ServiceThe 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 ServiceThe 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 AgencyWater 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 EnvironmentDHI, 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 ProgramNational 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 SystemsBentley 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 SolutionsXP Solutions
5415 SW Westgate Dr.
Suite 150
Portland, OR 97221

XPSolutions.com
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 SolutionsXP Solutions
5415 SW Westgate Dr.
Suite 150
Portland, OR 97221

XPSolutions.com
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)
USACEUS Army Engineering Research and Development Center, Coastal & Hydraulics Laboratory
3909 Halls Ferry Rd
Vicksburg, MS 39180
http://gsshawiki.com
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 at http://chl.erdc.usace.army.mil/gssha

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 EngineersU.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 EnvironmentDHI, 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 SurveyU.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)
USACEUS Army Engineering Research and Development Center, Coastal & Hydraulics Laboratory
3909 Halls Ferry Rd
Vicksburg, MS 39180
http://gsshawiki.com
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 at http://chl.erdc.usace.army.mil/gssha

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

PROGRAMDEVELOPED BYAVAILABLE FROMCOMMENTS
Single Event
VCRat 2.6 (Dec. 2008)Ventura County Watershed Protection DistrictVentura 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. 06Jimmy S. O'BrienFLO-2D Software, Inc.
P.O. Box 66
Nutrioso, AZ 85932

www.flo-2d.com/

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.

Only accepted for usage within Mohave County, Cochise County, and Pima County, Arizona

Public Domain: No

View More Nationally and Locally Accepted Models

Below are additional nationally and locally accepted models in the NFIP Program:

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: 
01/22/2015 - 10:32
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