SWAT Literature Database for Peer-Reviewed Journal Articles

Title:Assessment of model configuration effect by alternative evapotranspiration, runoff, and water routing functions on watershed modeling using SWAT 
Authors:Yen, H., J. Jeong, X. Wang, S. Lu, M. Kim and Y-W. Su 
Journal:Transactions of the ASABE 
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URL (non-DOI journals): 
Broad Application Category:hydrologic & pollutant 
Primary Application Category:calibration, sensitivity, and/or uncertainty analysis 
Secondary Application Category:computational efficiency 
Watershed Description:1,692 km^2 Arroyo Colorado River, located in the Lower Rio Grande Valley in southern Texas, U.S. 
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Validation Summary: 
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Abstract:The choice of different model structure and the subsequent parameter identification are relevant and usually have a strong subjective component. The impacts of various decisions associated with the internal configuration of a given watershed model need greater exploration to ensure confidence in hydrologic and water quality modeling results, yet they are often overlooked. In this study, a non-subjective approach in selecting alternative method is developed. The goal is to assess the impact of different configurations of the Soil and Water Assessment Tool (SWAT) model on consequential hydrologic and water quality behavior. A total of 12 SWAT configurations, each containing a unique combination of alternative algorithms in estimating surface runoff, potential evapotranspiration, and water routing, were calibrated against flow and nutrient data using the Dynamically Dimensioned Search (DDS) optimization algorithm. The assessment ensures that non-subjective decisions are formed by fully exploring different model configurations and consequences in the optimization process. The accuracy of calibrated outputs was sensitive to the choice of alternative methods, especially in ammonia-N predictions: NSE values varied from 0.23 to 0.67 (streamflow), 0.59 to 0.82 (sediment), -0.15 to 0.66 (ammonia-N). Similarly, uncertainty in the calibrated outputs varied among alternative methods: inclusion rate varied from 31% to 58% (streamflow), 46% to 71% (sediment), 25% to 87% (ammonia-N). The result highlights the significance of the non-subjectivity on selecting alternative method in the calibration of complex watershed model. The potential impact of selecting alternative methods should be fully explored in advance before further applications of complex watershed simulation models. 
Keywords:Optimization; Model calibration; Uncertainty analysis; SWAT; IPEAT