Model
SWAT (Soil and Water Assessment Tool)

SWAT is the product of over 40 years of research and is subject to ongoing development. The model is designed to simulate the effects of changes in land management practices, land use and climate on surface water and groundwater quality and quantity, sediments, nutrients, and pesticide yields within catchments.

Version
ArcSWAT version 2012.10.0.14, SWAT2012 revision 622.
Contact
United States Department of Agriculture Agricultural Research Service and Texas A&M AgriLife Research , https://www.ars.usda.gov/ and http://agriliferesearch.tamu.edu/)
Keywords
License
SWAT: freely available executable version. ArcSWAT: commercial license required for ArcGIS.
Operating Requirements
Runs on any standard computer but ArcSWAT requires ArcGIS.
Application Type
Executable.
User Interface
Windows, graphical user interface.
Support Available
Development team support and user group support (see http://swat.tamu.edu/support for information).
Application Scale
catchment
Geographical Restrictions
None. SWAT has been tested in a wide variety of global locations.
Temporal Resolution
Daily; monthly; and yearly.
Spatial Resolution
The model operates and provides outputs at the following scales: hydrologic response unit; sub-catchment; catchment; and river reach.
Primary Purpose
Pollutant loss studies; climate change impacts; hydrologic assessments; best management practice analysis; land use and management impacts.
Key Output Variables
River discharge; surface runoff; in-stream nutrient, sediment and pesticide loads.
Key Input Variables
Meteorological data (precipitation, maximum and minimum air temperature, relative humidity; solar radiation; wind speed); land use map; soil map; topographic map.
Calibration Required
Key model parameters that require calibration may first be identified from the literature. Sensitivity analysis should then be used to identify parameters that model outputs are sensitive to. Model calibration should then be performed to optimize the values assigned to model parameters.
Model Structure
Semi-physically based; semi-distributed; continuous time-step.
Model Parameterisation
The values of key parameters can be determined from observed data. Although some of the initial values assigned to key parameters may be based on expert judgement their final values should be optimized through model calibrat
Input Data Available on CaMMP Catalogue
No
Documentation
http://swat.tamu.edu/documentation/

Key References

  • Arnold, J.G., Moriasi, D.N., Gassman, P.W., Abbaspour, K.C., White, M.J., Srinivasan, R., Santhi, C., Harmel, R.D., van Griensven, A., Van Liew, M.W., Kannan, N. and Jha, M.K., 2012. SWAT: Model Use, Calibration, and Validation. Transactions of the ASABE, 55(4), pp.1491-1508. DOI: 10.13031/2013.42256.
  • Arnold, J.G., Srinivasan, R., Muttiah R.S. and Williams, J.R., 1998. Large Area Hydrologic Modeling and Assessment Part I: Model Development. Journal of the American Water Resources Association, 34(1), pp.73-89. DOI: 10.1111/j.1752- 1688.1998.tb05961.x.
  • Neitsch, S.L., Arnold, J.G., Kiniry, J.R. and Williams, J.R., 2011. Soil and Water Assessment Tool Theoretical Documentation Version 2009. [pdf] College Station: Texas Water Resources Institute. Available at: <http://swat.tamu.edu/media/99192/swat2009-theory.pdf>.

Input Data

  • 1) Name: Precipitation; type: time series; units: mm; resolution: daily; format: text file time series. 2) Name: Minimum and maximum air temperature; type: time series; units: degrees centigrade; resolution: daily; format: text file time series. 3) Name: Solar radiation; type: time series; units: MJ m-2; resolution: daily; format: text file time series. 4) Name: Mean wind speed; type: time series; units: m s-1; resolution: daily; format: text file time series. 5) Name: Mean relative humidity; type: time series; units: %; resolution: daily; format: text file time series. 6) Name: Digital terrain model; type: geographic dataset; format: raster. 7) Name: Land use map; type: geographic dataset; format: raster or vector. 7) Name: Soil map; type: geographic dataset; format: raster or vector

Output Data

  • 1) Name: mean discharge; type: time series; units: m3 s-1; resolution: daily, monthly, annual; format: text file time series. 2) Name: in-stream nitrate, total phosphorus, sediment and pesticide load; type: time series; units: kg; resolution: daily, monthly, annual; format: text file time series. 3) Name: in-stream total phosphorus load; type: time series; units: kg; resolution: daily, monthly, annual; format: text file time series. 4) Name: in-stream sediment load; type: time series; units: kg; resolution: daily, monthly, annual; format: text file time series. 5) Name: in-stream pesticide load; type: time series; units: mg active ingredient; resolution: daily, monthly, annual; format: text file time series.

Quality Assurance

Developer Testing
Unknown
Internal Peer Review
Unknown
External Peer Review
Unknown
Use of Version Control
Yes
Internal Model Audit
Unknown
External Model Audit
Unknown
Quality Assurance Guidelines and Checklists
Unknown
Governance
Unknown
Transparency
Yes
Periodic Review
Yes