SWAT Literature Database for Peer-Reviewed Journal Articles

Title:Comparison of four models (STEPL, PLOAD, L-THIA, and SWAT) in simulating sediment, nitrogen, and phosphorus loads and pollutant source areas 
Authors:Nejadhashemi, A.P., S.A. Woznicki and K.R. Douglas-Mankin 
Journal:Transactions of the ASABE 
Article ID: 
URL (non-DOI journals):http://cat.inist.fr/?aModele=afficheN&cpsidt=24363287 
Broad Application Category:hydrologic & pollutant 
Primary Application Category:model comparison 
Secondary Application Category:pollutant cycling/loss and transport 
Watershed Description:836 km^2 Pomona Lake in eastern Kansas, U.S. 
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Validation Summary: 
General Comments: 
Abstract:This study compared the utility and results of four watershed models that include water quality elements: Spreadsheet Tool for Estimating Pollutant Load (STEPL), a GIS‐based model to calculate pollutant loads for watersheds (PLOAD), Long‐Term Hydrologic Impact Assessment (L‐THIA), and ArcGIS Soil and Water Assessment Tool (ArcSWAT). These models are different in their levels of complexity, data requirements, time step, and simulation techniques. Therefore, different scenarios were conducted to test some of the standard applications of each model based on data quality and model capabilities. Climatological, land use, and soil datasets as well as flow rates, sediment, nitrate, and total P concentrations were collected for the Pomona Lake watershed in Kansas over 30 years. Stakeholders' information was integrated into the models to the extent possible. Using results obtained from STEPL, L‐THIA, PLOAD, and uncalibrated ArcSWAT for estimating long‐term (30 years) average pollution loads in a watershed can result in incorrect load estimation. In addition, the STEPL, L‐THIA, and PLOAD models may not be the most reliable in identifying pollutant source areas in a watershed. Therefore, in the context of effective resource allocation, use of simple models (such as STEPL, L‐THIA, and PLOAD) is not suggested for critical source area targeting for watershed planning if the nature of the problem is complex. However, the simple models can still be used to evaluate relative contribution of different land uses to overall pollution loads. 
Keywords:L-THIA, PLOAD, STEPL, SWAT, Water quality model