Model:WEPP

WEPP

WEPP Questionnaire

Contact Information

Model:	WEPP
Contact person:	Dennis Flanagan (Project Manager)
Institute:	USDA-Agricultural Research Service
City:	West Lafayette, Indiana
Country:	USA
Email:	flanagan@purdue.edu
2nd person involved:	Jim Frankenberger (Technical contact)
3rd person involved:	--

Model Description

Model type:

Modular model for the terrestrial and hydrologocial domain.

Description:

The Water Erosion Prediction Project (WEPP) model is a process-based, distributed parameter, continuous simulation erosion prediction model for application to hillslope profiles and small watersheds. Interfaces to WEPP allow its application as a stand-alone Windows program, a GIS-system (ArcView, ArcGIS) extension, or in web-based links. WEPP has been developed since 1985 by the U.S. Department of Agriculture for use on croplands, forestlands, rangelands, and other land use types.

Technical information

Supported platforms:	UNIX, Linux, Windows
Programming language:	Fortran77, Fortran90
Model development started at:	1985 and development still takes place.
To what degree will the model become available:	Source code & executable will be available and model can be used as teaching tool. Code will be available for collaborators.
Current license type:	--
Memory requirements:	--
Typical run time:	<1 minute for hillslope simulations

Input / Output description

Input parameters:	Daily climate input: (temperatures, precipitation depth, duration, Tp, Ip, wind info) slope input: (distance downslope, slope at points, profile width, aspect) soil input: (infiltration & erodibility parameters, soil layer depth, texture, organic matter, CEC, etc. cropping/management input: (plant growth parameters, residue decomposition parameters, tillage operation parameters, residue management parameters, dates of operations (planting, harvest, tillage, residue management, etc.)) irrigation input: (type of irrigation, date(s) of irrigation, application rates, etc.) channel parameters input: (channel shape, width, slope, roughness, etc.) impoundment parameters input: (type of impoundment (1. Drop Spillway 2. Perforated Riser 3. Culvert 4. Emergency Spillway or Open Channel 5. Rock Fill Check Dam 6. Filter Fence / Straw Bales / Trash Barriers 7. User Specified Stage-Discharge Relationship, parameter inputs specific to each impoundment type)) watershed structure file: (describes how all hillslopes, channels, and impoundments in a watershed are linked).
Input format:	ASCII
Output parameters:	Storm, monthly, yearly, or average annual runoff, soil loss, and sediment yield from a hillslope profile. Spatial distribution of soil erosion and deposition on slope profiles. Graphical output available of 92 parameters from continuous model simulations (including precip, temperatures, runoff, soil loss, sediment yield, biomass production, residue cover, etc.). Soil output text file, water balance output text file, plant output text file, storm event output file, overland flow element summary line output file.
Output format:	ASCII
Post-processing software (if needed):	No, WEPP Windows or web-based interfaces can be used without any other software, besides that included in the model installation (or with web-browser for the browser interfaces). GeoWEPP requires ArcView or ArcGIS as the GIS system.
Visualization software (if needed):	Yes, ESRI.

Process description

Processes represented by model:	Climate generation (CLIGEN), infiltration, percolation, evapotranspiration, plant growth, residue management and decomposition, runoff, hydralics of overland flow, soil detachment by raindrop impact and shallow flow (interrill), soil detachment by excess flow shear stress (rill, channel), sediment transport, sediment deposition, irrigation, winter processes (snow melt, frost, thaw), channel erosion processes, sedimentation in impoundments.
Key physical parameters & equations:	Rain storm depth, storm duration, storm intensity - driving variables; effective hydraulic conductivity - controls infiltration into soil; baseline soil erodibility parameters (interrill erodibility, rill erodibility, critical hydraulic shear stress) - control soil detachment rates; slope inputs - control amount of flow shear stress and sediment transport capacity available to detach and tranport soil/sediment; plant growth parameters - control the production of biomass that protects soil surface; residue decomposition parameters - control the rate of residue loss from soil surface; tillage operation parameters - control the amount of soil disturbance and burial of residue - both of which impact the adjusted erodiblities for a given day.
Length scale & resolution constraints:	Hillslope simulations are recommended for lengths not greatly exceeding 100 meters. Watershed simulations should not exceed areas above 260 hectares. Larger areas can be simulated for hillslope spatial analyses only - but the channel processes will not be accurate at these larger scales.
Time scale & resolution constraints:	The model can be run for a single storm (minutes to hours), and can also be run in continuous simulation mode for any number of years (1 - 100+).
Numerical limitations and issues :	--

Testing

Available calibration data sets:	Data available from 1986-88 field experimentation (in compendium) using rainfall simulation. Also, validation data sets are available from USLE database.
Available test data sets:	--
Ideal data for testing:	Ideal data would consist of breakpoint (recording raingage) rainfall data, observed temperatures, radiation, wind, plant cover, residue cover, storm runoff, storm sediment loss, etc.

User groups

Currently or plans for collaborating with:

Yes.

Documentation

Key papers of the model:	Flanagan, D.C., J.E. Gilley and T.G. Franti. 2007. Water Erosion Prediction Project (WEPP): development history, model capabilities, and future enhancements. Trans. Am. Soc. Agric. Biol. Eng. 50(5):1603-1612.
Is there a manual available:	yes
Model website if any:	http://www.ars.usda.gov/Research/docs.htm?docid=10621

Additional comments

Comments:

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