SWAT Literature Database for Peer-Reviewed Journal Articles

Title:Hydrologic simulation on agricultural watersheds: choosing between two models 
Authors:Van Liew, M.W., J.G. Arnold and J.D. Garbrecht 
Journal:Transactions of the ASAE 
Volume (Issue):46(6) 
Article ID: 
URL (non-DOI journals): 
Broad Application Category:hydrologic only 
Primary Application Category:model and/or data comparison 
Secondary Application Category:hydrologic assessment 
Watershed Description:610 km^2 Little Washita, located in southwest Oklahoma, U.S. [Calibration was performed on subwatersheds 442 (33.3 km^2) & 526 (160 km^2); validation performed on subwatersheds 408 (2.9 km^2), 483 (4.3 km^2), 406 (9.0 km^2), 458 (16.8 km^2), 522 (537.7 km^2) & 560 (610 km^2), and neighboring Delaware Creek (103.8 km^2) & Salt Creek (61.5 km^2) watersheds] 
Calibration Summary:Oct. 1992 - Sept. 2000: 442 monthly E/daily E/ daily r2 = .79/.58/.97 ---------------------------- Feb. 1992 - Sept. 2000: 526 monthly E/daily E/daily r2 = .66/.56/.97 ---------------------------- Jan. 1981 - Dec. 1985: 526 monthly E/daily E/daily r2 = ..85/.72/.92 
Validation Summary:13 monthly E values ranged from -1.05 to .89 (2 < 0.0; 11 > .43; 9 > .52) ---------------------------- 13 daily E values ranged from -.35 to .63 (4 < 0.0; 7 > .42; 4 > .54) ----------------------------12 daily r2 values ranged from .83 to .96 (9 > .90) 
General Comments:SWAT and HSPF were compared for 8 nested subwatersheds (incudling entire watershed) and two nearby watersheds. Calibration was performed on tw of the subwatersheds; validations were performed using the other subwatersheds. HSPF performed better on the calibration watersheds while SWAT performed better on the validation watersheds. Overall, SWAT was found to produce more consistent results than HSPF. 
Abstract:Strengths and limitations of hydrologic simulation models are used as criteria for selecting a particular model for a given water resources application. The performance of the Soil and Water Assessment Tool (SWAT) and the Hydrologic Simulation Program-Fortran (HSPF) continuous simulation models was compared on eight nested agricultural watersheds within the Little Washita River Experimental Watershed (LWREW) and two agricultural watersheds adjacent to the LWREW within the Washita River Basin in southwestern Oklahoma. Two subwatersheds within the LWREW were first used to calibrate parameters in both models for a “wetter than average” period of record. Both models were then applied to six other subwatersheds within the LWREW and the two adjacent watersheds, under varying climatic conditions. Three quantitative and two qualitative evaluation criteria were used to assess streamflow simulated by SWAT and HSPF: computation of (1) deviation of streamflow volume, (2) coefficient of efficiency, and (3) prediction efficiency and visual inspection of (4) hydrographs and (5) flow duration curves. A comparison of model performance showed that while HSPF performed better on the watersheds used for calibration, SWAT gave better results on the validation watersheds. On one of the validation subwatersheds adjacent to the LWREW, values of deviation of streamflow volume were -38.7%, -13.3%, and -1.3% for SWAT and -64.3%, -81.1%, and -8.2% for HSPF under “much dryer than average,” “dryer than average,” and “near average” climatic conditions, respectively. Differences in model performance were mainly attributed to the runoff production mechanism in the two models. Results of this study showed that SWAT exhibited an element of robustness in that it gave more consistent results than HSPF in estimating streamflow for agricultural watersheds under various climatic conditions. SWAT may therefore be better suited for investigating the long-term impacts of climate variability on surface-water resources. 
Keywords:Modeling; America; North America; United States; Model calibration; Soils; Oklahoma; Streamflow; Model study; Comparative study; Performance evaluation; Watershed; Climate variation; Simulation model; Hydraulic model; Water resource management; Hydrology