SWAT Literature Database for Peer-Reviewed Journal Articles

Title:Quantifying the effects of future climate conditions on runoff, sediment, and chemical losses at different watershed sizes 
Authors:Wallace, C.W., D.C. Flanagan and B.A. Engel 
Journal:Transactions of the ASABE 
Article ID: 
URL (non-DOI journals): 
Broad Application Category:hydrologic & pollutant 
Primary Application Category:climate change  
Secondary Application Category:pollutant cycling/loss and transport 
Watershed Description:679 km^2 Cedar Creek, and three subwatersheds that cover 19.7 km^2, 41.5 km^2 and 182.5 km^2. Cedar Creek is a tributary of the Joseph River in northeast Indiana, U.S. 
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General Comments: 
Abstract:. Quantifying the effects of climate change on watershed hydrology and agricultural chemical losses is imperative when developing appropriate management practices for agricultural watersheds. Agricultural management practices are often assessed at the watershed scale; therefore, understanding the influence of climate change at different watershed sizes can provide insight into the effectiveness of watershed management strategies. In this study, the Soil and Water Assessment Tool (SWAT) and downscaled weather data generated using the MarkSim weather file generator were used to evaluate the potential impact of climate change in the hydrologically modified Cedar Creek (CCW), F34, AXL, and ALG watersheds located in northeastern Indiana. This study evaluated changes in surface flow, tile flow, sediment, and agricultural chemical losses based on an ensemble mean of the 17 general circulation models (GCMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5). We found no clear evidence that watershed size had an impact on the simulation of climate change effects on discharge or nutrient losses. Results of this study indicated that predicted surface flow decreased significantly toward the end of this century (ranging from 9% in CCW to 22% in ALG), while predicted subsurface tile flow increased significantly (ranging from 20% in CCW to 26% in AXL). The percentage increases in predicted sediment loss for the CCW, AXL, and ALG watersheds were significant at alpha = 0.05, although the magnitudes of overall sediment losses were low, especially in the smaller monitored watersheds (F34, AXL, and ALG) in which several best management practices are implemented. Differences in predicted atrazine, soluble N, total N, and total P losses between the baseline period (1961- 1990) and the end of this century were not significant for any of the watersheds, while increased predicted soluble P losses were only significant for the larger CCW and F34 watersheds. 
Keywords:Climate change, MarkSim, Surface flow, SWAT, Tile flow.