Soil Erosion Network: Model Metadata
WEPP - Water and Wind Erosion

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1 Model identification Soil Erosion Network - Model
1.1 Model name WEPP - Water and Wind Erosion
1.2 Most recent version 95.0
1.3 Date of release January 1995
2 Water erosion and Wind Erosion
3 Contact person
3.1 Name Mark Nearing
3.2 Address 1196 Soil Building,
Purdue U, W Lafayette IN
3.3 Tel +1 317 494 8683
3.4 Fax +1 317 494 5948
3.5 Email
4 Model Author(s) Nearing, Flanagan, Nicks, Laflen, Gilley, Weltz, Alberts, Young, Foster, Savabi, Rawls, Lane, Stone
5 Model components
5.1 Water erosion: Entirely new and validated on >2000 plot years
5.2 Wind erosion: No
5.3 Hydrology: Green Ampt Infiltration. Kinematic Wave Routing
5.4 Site/topography: Complex Topography, multiple land use
5.5 Plant growth: Epic variant
5.6 Management: Extensive data required. Tilage dates - harvest dates - etc.
5.7 Soil: Basic information required
5.8 Chemistry: No
5.9 Weather: CLIGEN or measured input
6 Model characteristics
6.1 Spatial Field or small watershed
6.1.1 Class of area:
6.1.2 Flow routing system: Channels and hillslopes (maybe run separately)
6.1.3 Minimum area: 1 x 1 m
6.1.4 Maximum area: 640 to ha
6.2. Temporal Single storm or multi-year
6.2.1 Timestep: Daily
6.2.2 Single or multiple event? Both
6.2.3 Maximum simulation duration: None recommended. No computational limits
7 Model's representation of processes
7.1 Water erosion processes Erodibility from est. egs.
7.1.1 Interrill: Ki Ig Sf Cf 6f. Intensity rainfall g = runoff.
7.1.2 Rill: Shear stress model/Yalin Transport
7.1.3 Gully: Ephemeral channels only. No classical gullies
7.1.4 Streambank: No
7.1.5 Deposition: Yes and sediment sorting
7.2 Wind erosion processes:
7.2.1 Creep/surface roll:
7.2.2 Saltation:
7.2.3 Suspension
7.3 Hydrological processes:
7.3.1 Evaporation/transpiration: Penman or Hargraves+
7.3.2 Runoff: Kinematic Wave
7.3.3 Infiltration Green Ampt
7.3.4 Subsurface flow: Yes
7.3.5 Return flow Yes
7.4 Plant processes:
7.4.1 Light interception and photsynthesis: EPIC derived
7.4.2 Dry matter and residue
7.4.3 Root growth:
7.4.4 Pests:
7.4.5 CO2 sensitivity: Yes - in-house version
7.5 Soil: Tillage, consolidation, freeze/thaw
7.5.1 Crust development Yes - rainfall energy calculated
7.5.2 Aggregate properties Yes - Foster/Young/Niebling method
7.6 Chemistry:
7.6.1 Nutrients:
7.6.2 Carbon
7.6.3 Pesticides
7.6.4 Other contaminants
7.7 Weather: CLIGEN or measured data
7.8 Other:
8 Input Data (* = Mandatory)
8.1 Weather: Daily precipitation*, maximum minimum temperature*, sola radiation*, dewpoint* wind
8.2 Soil: Texture, CEC, rocks, erodibility (est. equations provided)
8.3 Hydrology: Computed internally
8.4 Plant cover: Computed internally
8.5 Soil surface cover: Computed internally
8.6 Management: Plant parameters, tillage parameters, plant and harvest dates
8.7 Topography/site characteristics: = Slope at points along profile
8.8 Micro-topography: Internally calculated
8.9 Other Irrigation, if active channel information
9 Output data Daily runoff, peak runoff, soil loss, detachment, deposition, sediment yield, change in erodibility, infiltribility - also annual values crop yield (there are literally hundreds of output variables)
10 Programming language FORTRAN/C
11 Computer requirements 386 W/Coprocessor or better
12 Documentation
12.1 Scientific documentation: On-line Internet access to all documentation is coming
12.2 User's guide: Currently on-line
12.3 Technical documentation: Soon on-line
13 Availability From Internet or by request
14 Other Relevant Information This model represents the work of several USDA-ARS scientists spanning a 10-year period. It has been well-tested in hillslope applications and works very well. Watershed applications have not been as well validated. We are currently modifying the program to study the effect of CO2 and temperature change on hydrologic and erosion processes.

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