Implications of Conceptual Channel Representation on SWAT Streamflow and Sediment Modeling |
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Authors: | Younggu Her Jaehak Jeong Katrin Bieger Hendrik Rathjens Jeffrey Arnold Raghavan Srinivasan |
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Institution: | 1. Department of Agricultural and Biological Engineering, University of Florida, Homestead, Florida;2. Blackland Research and Extension Center, Texas A&M University, Temple, Texas;3. Stone Environmental, Montpelier, Vermont;4. Grassland Soil and Water Research Laboratory, USDA Agricultural Research Service, Temple, Texas;5. Department of Ecosystem Science and Management, Texas A&M University, College Station, Texas |
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Abstract: | Hydrologic modeling outputs are influenced by how a watershed system is represented. Channel routing is a typical example of the mathematical conceptualization of watershed landscape and processes in hydrologic modeling. We investigated the sensitivity of accuracy, equifinality, and uncertainty of Soil and Water Assessment Tool (SWAT) modeling to channel dimensions to demonstrate how a conceptual representation of a watershed system affects streamflow and sediment modeling. Results showed the amount of uncertainty and equifinality strongly responded to channel dimensions. On the other hand, the model performance did not significantly vary with the changes in the channel representation due to the degree of freedom allowed by the conceptual nature of hydrologic modeling in the parameter calibration. Such findings demonstrated good modeling performance statistics do not necessarily mean small output uncertainty, and partial improvements in the watershed representation may neither increase modeling accuracy nor reduce uncertainty. We also showed the equifinality and uncertainty of hydrologic modeling are case‐dependent rather than specific to models or regions, suggesting great caution should be used when attempting to transfer uncertainty analysis results to other modeling studies, especially for ungauged watersheds. 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: | channel dimension
SWAT
equifinality uncertainty hydrology sediment |
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