Model Description and Availability

SWAT
Soil and Water Assessment Tool (SWAT) is an USDA - Agricultural Research Service computer model to predict the effect of management decisions on water, sediment, nutrients, and pesticides yields in larger ungaged river basins. In utilizes SWRRBWQ technology enhanced with reach routing and capability to subdivide into more than 100 sub basins. Tool has components for weather, surface runoff, return flow, percolation, ET, transmission losses, pond & reservoir storage, crop growth & irrigation, groundwater flow, reach routing, nutrient & pesticide loading, and water transfer. Model is GIS linked.

Project manager or lead scientist – Jeff Arnold, USDA-ARS – Temple, TX

More information at http://www.brc.tamus.edu/swat/index.html

APEX
Agricultural Policy/Environmental eXtender (APEX) is a USDA-ARS and Texas A&M computer model which provides a tool for managing whole farms or small watersheds while maximizing production efficiency and maintaining environmental quality. Components available for hydrology, water and wind erosion, N and P cycling pesticide fate, soil temperature, plant growth, tillage, and economics.

Project manager or lead scientist – Jimmy Williams, Texas Agricultural Experiment Station Temple, TX

More information at apex@brc.tamus.edu

EPIC
Erosion/Productivity Impact Calculator (EPIC) is an USDA - Agricultural Research Service developed field sized model used to determine the effect of management strategies on water quality. EPIC provides the following outputs: (1) Water movement - volume of surface runoff, days of runoff, and percolation below the root zone. (2) N loss in percolate and subsurface flow used to assess hazards to ground water. (3) Nutrient loss in surface runoff and erosion - soluble and attached N, and soluble P and P loss with sediment. (4) Erosion assessment - sediment loss and associated chemicals. (5) Pesticide loss in runoff and below the root zone - for selected pesticides.

Project manager or lead scientist – Jimmy Williams Texas Agricultural Experiment Station Temple, TX

More information at http://www.brc.tamus.edu/epic/index.html

GLEAMS
Groundwater Loading Effects of Agricultural Management Systems (GLEAMS) is a continuous simulation, field scale model, which was developed as an extension of the Chemicals, Runoff and Erosion from Agricultural Management Systems (CREAMS) model. GLEAMS assumes that a field has homogeneous land use, soils, and precipitation. It consists of four major components: hydrology , erosion/sediment yield, pesticide transport, and nutrients. GLEAMS was developed to evaluate the impact of management practices on potential pesticide and nutrient leaching within, through, and below the root zone. It also estimates surface runoff and sediment losses from the field. GLEAMS was not developed as an absolute predictor of pollutant loading. It is a tool for comparative analysis of complex pesticide chemistry, soil properties, and climate. GLEAMS can be used to assess the effect of farm level management decisions on water quality. Recently updated to version 3.0.

Project manager or lead scientist – Daren Harmel, USDA-ARS, Temple, TX

More information at http://www.cpes.peachnet.edu/sewrl/Gleams/gleams_y2k_update.htm

NLEAP
Nitrate Leaching and Economic Analysis Package (NLEAP) is a field-scale computer model developed to provide a rapid and efficient method of determining potential nitrate leaching associated with agricultural practices. It combines basic information concerning on-farm management practices, soils, and climate and then translates the results into projected N budgets and nitrate leaching below the root zone and to ground water supplies, and estimates the potential off site effects of leaching.

Project manager or lead scientist – Marv Shaffer, USDA-ARS Fort Collins, CO

More information at  http://www.wcc.nrcs.usda.gov/nutrient/nutrient-nitrogen.html

RZWQM
Root Zone Water Quality Model (RZWQM) developed by USDA-ARS simulates major physical, chemical, and biological processes in an agricultural crop production system. RZWQM is a one-dimensional (vertical in the soil profile) process-based model that simulates the growth of the plant and the movement of water, nutrients and agro-chemicals over, within and below the crop root zone of a unit area of an agricultural cropping system under a range of common management practices. The model includes simulation of a tile drainage system.

Project manager or lead scientist – Laj Ahuja, USDA-ARS, Fort Collins, CO

More information at http://gpsr.ars.usda.gov/products/rzwqm.htm

DRAINMOD
DRAINMOD is a computer simulation model developed by Dr. Wayne Skaggs at Department of Biological & Agricultural Engineering, North Carolina State University, Raleigh, NC in 1980. The model simulates the hydrology of poorly drained, high water table soils on an hour-by-hour, day-by-day basis for long p eriods of climatological record (e.g. 40 years). The model predicts the effects of drainage and associated water management practices on water table depths, the soil water regime and crop yields. It has been used to analyze the hydrology of certain types of wetlands and to determine whether the wetland hydrologic criterion is satisfied for drained or partially drained sites. The model is also used to determine the hydraulic capacity of systems for land treatment of wastewater.

Project manager or lead scientist – Wayne Skaggs at Department of Biological & Agricultural Engineering, North Carolina State University, Raleigh, NC

More information at http://www.bae.ncsu.edu/bae/programs/extension/wqg/kevin/wetrest/modling.htm

SPAW
Soil - Plant - Air - Water (SPAW) The SPAW+ model is a daily hydrologic budget model for agricultural fields with a moderate level of complexity to account for the most important hydrologic processes which will be impacted by the field characteristics. The model inputs describe the climate, soils and crops of a particular farm field in the one dimensional vertical plane. The climate variables, the principle hydrologic inputs, are daily rainfall and evaporation with optional air temperature for cold climate hydrology. The soils and crop descriptions determine the daily disposition of this water into and out of the soil-plant-air- water (SPAW) system. The basic hydrologic budgeting has been enhanced by the addition of an irrigation field budget (scheduling) and an inundated pond (wetland/lagoon.pond/reservoir) budget, thus the name designation.

Project manager or lead scientist – Keith Saxton, USDA-ARS, Pullman, WA

More information at http://www.bsyse.wsu.edu/saxton/spaw/

SPUR
Simulation of Production and Utilization on Rangeland (SPUR) is an ARS developed rangeland ecosystem model. The model has two versions: field level and watershed. Plant growth and hydrologic status are used to determine runoff and sedimentation from rangeland. Development and testing of SPUR is nearly complete, and the model should be released soon. NTC range conservationists will provide technical support.

Project manager or lead scientist – Kenneth Spaeth, USDA-NRCS, Boise, ID

More information at http://www.nps.ars.usda.gov/projects/projects.htm?ACCN_NO=406005

REMM
The Riparian Ecosystem Management Model (REMM) is a computer simulation model. REMM is used to simulate hydrology, nutrient dynamics and plant growth for land areas between the edge of fields and a water body. Output from REMM will allow designers to develop buffer systems to help control non-point source pollution.

Project manager or lead scientist – Richard Lowrance, USDA-ARS Tifton, GA

More information at http://www.cpes.peachnet.edu/remmwww/

CROPFLEX
CROPFLEX developed by Colorado State University, it provides recommendations for producers on irrigation timing and nutrient scheduling. Crop development and irrigation needs are driven by local climatic inputs. Nutrient balances are determined and a seasonal accounting is made as to plant uptake depending on the health and vigor of the plant from appropriate timing and amounts of irrigation. Depending on plant health and vigor, a mid year correction is presented to allow for modification of nutrient applications. Nutrient needs are based on yields and input soil sampling information.

Project manager or lead scientist – Israel Broner, Colorado State University, Fort Collins, CO

More information at http://ulysses.atmos.colostate.edu/~crop/

SRFR
Surface Irrigation Tool (SRFR) is a program with which simulations are currently possible for basins with or without drainback; borders; furrows; surge flows; cutbacks; cablegation in uniform or spatially or temporally varied geometry, roughness; and infiltration. An experimental treatment of irrigation- induced erosion and deposition is available for cooperating researchers. Thus, in keeping with other engineering disciplines, trial designs or operating schemes can be rapidly evaluated as input to a program of successive analyses to approach desired performance and cost criteria. a model to help identify the optimum surface irrigation efficiencies from border, basin, and furrow irrigation.

Project manager or lead scientist – Fredja Strelkoff, USDA-ARS Phoenix, AZ

More information at fstrelkoff@uswcl.ars.ag.gov

WEND
Watershed Ecosystem Nutrient Dynamics (WEND) model is a simulation model of a complex watershed ecosystem in which people live, work, and play. The watershed comprises forest lands, land in agriculture, and urban land areas devoted to commerce, industry, and habitation. The model, constructed using the conceptual watershed ecosystem, links the models of the agriculture, forestry, and urban sectors. These linkages create an overall model that describes P storage and fluxes as an integrated whole system, that is, as a complex watershed ecosystem.

Project manager or lead scientist – Alan Cassell, University of Vermont

More information at http://nature.snr.uvm.edu/acassell/wend/models.html

WEPP
The Water Erosion Prediction Project (WEPP) model is a process-based, distributed parameter, continuous simulation, erosion prediction model for use on personal computers. The current version (v99.5) available through the Internet is applicable to hillslope erosion processes (sheet and rill erosion), as well as simulation of the hydrologic and erosion processes on small watersheds.

Project manager or lead scientist – John Laflin, USDA-ARS West Lafayette, IN

More information at http://topsoil.nserl.purdue.edu/nserlweb/weppmain/wepp.html

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