How to Constrain Multi‐Objective Calibrations of the SWAT Model Using Water Balance Components |
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| Authors: | Matthias Pfannerstill Katrin Bieger Björn Guse David D. Bosch Nicola Fohrer Jeffrey G. Arnold |
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| Affiliation: | 1. Department of Hydrology and Water Resources Management, Institute for Natural Resource Conservation, University of Kiel, Kiel, Germany;2. Blackland Research and Extension Center, Texas A&M AgriLife, Temple, Texas;3. Southeast Watershed Research Laboratory, USDA Agricultural Research Service, Tifton, Georgia;4. Grassland, Soil and Water Research Laboratory, USDA Agricultural Research Service, Temple, Texas, 76502 |
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| Abstract: | Accurate discharge simulation is one of the most common objectives of hydrological modeling studies. However, a good simulation of discharge is not necessarily the result of a realistic simulation of hydrological processes within the catchment. We propose an evaluation framework that considers both discharge and water balance components as evaluation criteria for calibration of the Soil and Water Assessment Tool (SWAT). In this study, we integrated average annual values of surface runoff, groundwater flow, and evapotranspiration in the model evaluation procedure to constrain the selection of good model runs for the Little River Experimental Watershed in Georgia, United States. For evaluating water balance and discharge dynamics, the Nash‐Sutcliffe efficiency (NSE) and percent bias (PBIAS) were used. In addition, the ratio of root mean square error and standard deviation of measured data (RSR) was calculated for individual segments of the flow duration curve to identify the best model runs in terms of discharge magnitude. Our results indicate that good statistics for discharge do not guarantee realistic simulations of individual water balance components. Therefore, we recommend constraining the ranges of water balance components to achieve a more realistic simulation of the entire hydrological system, even if tradeoffs between good statistics for discharge simulations and reasonable amounts of the water balance components are unavoidable. Editor's note : This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series. |
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| Keywords: | optimizing multi‐objective model calibration expert knowledge constraints hydrological consistency signatures SWAT model |
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