SWAT Literature Database for Peer-Reviewed Journal Articles

Title:Hydrologic modeling/GIS as an aid in locating monitoring sites 
Authors:Rosenthal, W.D., and D.W. Hoffman 
Journal:Transactions of the ASAE 
Article ID: 
URL (non-DOI journals): 
Broad Application Category:hydrologic & pollutant 
Primary Application Category:pollutant cycling/loss and transport 
Secondary Application Category:none 
Watershed Description:9,000 km^2 Leon River (north central Texas) 
Calibration Summary: 
Validation Summary:Monthly stream flow (1972-74) E =0.57 
General Comments:Average annual nitrate and soluble P loads were 3.9 & 0.03 kg/ha; results used to help site monitoring stations in lower part of watershed, where subwatersheds had higher loads. Efficiency values were determined for flow at Gatesville having a 7,000 km^2 drainage area. 
Abstract:With the increasing importance and awareness of non-point source pollution, critical siting of water quality monitoring stations becomes important. Within large watersheds this siting becomes difficult because of the time and expense to travel the entire watershed and evaluate the area. Previous work has shown that hydrologic models can assist in evaluating water quality in large watersheds. In this study, the hydrologic model SWAT (Soil and Water Assessment Tool) was used to simulate flows, sediment and nutrient loadings on a 9000 km^2 watershed in central Texas for the period 1970-1984. The model is a continuous, daily time step model that predicts surface runoff, percolation, lateral subsurface flow, groundwater flow, transmission losses and flood routing. The Geographic Resources Analysis Support System (GRASS) and available Natural Resources Conservation Service databases provided input into SWAT. Subwatersheds demonstrating areas of highest per acre loadings were identified from model output. Modeled output of streamflow, nitrogen, phosphorus, and sediment loadings were analyzed. For 1972-1974, the correlation coefficient between observed and simulated streamflow was 0.83, while the Nash-Sutcliffe coefficient was 0.57 indicating the model is a better predictor than using the mean. Average annual loads from the entire basin were 3.9 kg ha–1 NO3 and 0.03 kg ha–1 soluble P. Subwatersheds in the lower part of the watershed had loads which were higher than the watershed average and as a result monitoring stations have been installed. The results demonstrate that a hydrologic model and available spatial databases can be used to aid in locating sites.