SWAT Literature Database for Peer-Reviewed Journal Articles

Title:Parameter sensitivity and uncertainty in SWAT: A comparison across five USDA-ARS watersheds 
Authors:Veith, T.L., M.W. Van Liew, D.D. Bosch and J.G. Arnold 
Journal:Transactions of the ASABE 
Volume (Issue):53(5) 
Article ID: 
URL (non-DOI journals): 
Broad Application Category:hydrologic only 
Primary Application Category:calibration, sensitivity, and/or uncertainty analysis 
Secondary Application Category:Conservation Effects Assessment Project (CEAP) based study 
Watershed Description:239 km^2 Reynolds Creek, 24 km^2 Walnut Gulch, 160 km^2 Little Washita River, 330 km^2 Little River, 239 km^2 Reynolds Creek and 7.2 km^2 Mahantango Creek, which are located respectively near the cities of Boise, Idaho; Tuscon, Arizona; Oklahoma City, Oklahoma; Tifton, Georgia; and Harrisburg, Pennsylvania, U.S. 
Calibration Summary: 
Validation Summary: 
General Comments: 
Abstract:The USDA‐ARS Conservation Effects Assessment Project (CEAP) calls for improved understanding of the strengths and weaknesses of watershed‐scale water quality models under a range of climatic, soil, topographic, and land use conditions. Assessing simulation model parameter sensitivity helps establish feasible parameter ranges, distinguish among parameters having regional versus universal interactions, and ensure that one model process does not compensate for another due to poor parameter settings. The Soil and Water Assessment Tool (SWAT) parameter sensitivity and autocalibration module was tested on two northern and three southern USDA‐ARS experimental watersheds. These previously calibrated watersheds represent a range of climatic, physiographic, and land use conditions present in the U.S. Sixteen parameters that govern basin, snow accumulation/melt, surface, and subsurface response in the model were evaluated. Parameters governing surface runoff due to rainfall were found most sensitive overall, while parameters governing groundwater were the least sensitive. Surface runoff parameters were found most sensitive for areas with high evaporation rates and localized thunderstorms. Parameters from all categories were important in areas where precipitation includes both rainfall and snowfall. Differences in model performance were noticeable on a climatic basis; SWAT generally predicted streamflow with less uncertainty in humid climates than in arid or semi‐arid climates. Study findings can be used to determine appropriate parameter ranges for ungauged watersheds of similar characteristics. 
Keywords:CEAP, Hydrology, Parameter uncertainty, Sensitivity, Simulation