The Soil and Water Assessment Tool: Historical Development, Applications, and Future Research Directions

The Soil and Water Assessment Tool (SWAT) model is a continuation of nearly 30 years of efforts conducted by the U. S. Department of Agriculture (USDA), Agricultural Service. SWAT has gained international acceptance as a robust interdisciplinary modeling tool, as evidenced by international SWAT conferences, hundreds of -related papers presented at numerous scientific meetings, and dozens of articles in peer-reviewed journals. The model has also been adopted as part of the U. S. Protection Agency’s BASINS (Better Assessment Science Integrating Point & Sources) software package and is being used by many U. S. federal and state, including the USDA within the Conservation Effects Assessment Project. At, over 250 peer-reviewed, published articles have been identified that report SWAT, reviews of SWAT components, or other research that includes SWAT. Many of peer-reviewed articles are summarized here according to relevant application categories such as streamflow calibration and related hydrologic analyses, climate change impacts on hydrology, pollutant load assessments, comparisons with other models, and sensitivity analyses and calibration techniques. Strengths and weaknesses of the model are presented, and recommended research needs for SWAT are provided.