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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #345034

Research Project: Resilient Management Systems and Decision Support Tools to Optimize Agricultural Production and Watershed Responses from Field to National Scale

Location: Grassland Soil and Water Research Laboratory

Title: Assessment of optional sediment transport functions via the complex watershed simulation model SWAT

item YEN, HAW - Texas Agrilife Research
item LU, SHENGLAN - Aarhus University
item FENG, QINGYU - Purdue University
item WANG, RUOYU - Environmental Protection Agency (EPA)
item GAO, JUNGANG - Texas Agrilife Research
item BRADY, DAWN - Aqua-Aerobic Systems, Inc
item SHARIFI, AMIRREZA - University Of Maryland
item AHN, JUNGKYU - Seoul National University
item CHEN, SHIEN-TSUNG - Feng Chia University
item JEONG, JAEHAK - Texas Agrilife Research
item White, Michael
item Arnold, Jeffrey

Submitted to: Water
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2017
Publication Date: 1/29/2017
Citation: Yen, H., Lu, S., Feng, Q., Wang, R., Gao, J., Brady, D.M., Sharifi, A., Ahn, J., Chen, S., Jeong, J., White, M.J., Arnold, J.G. 2017. Assessment of optional sediment transport functions via the complex watershed simulation model SWAT. Water. 9(76):1-19.

Interpretive Summary: Watershed models are routinely used to determine the impacts of land management and climate on water supply and water quality. It is critically important to realistically simulate sediment sources and sinks within the watershed to ensure accurate scenario analysis. In this study, we evaluated four alternative methods for predicting sediment transport through streams and rivers. The Yang method performed best, followed by Kodoatie, Bagnold, and Molinas and Wu equations. This research gives modelers and decision makers guidance on which sediment transport models are most appropriate for their study, ensuring that sediment budgets are realistically simulated. It also increases confidence that land management and climate scenarios are accurate and provide decision makers with viable alternatives.

Technical Abstract: The Soil and Water Assessment Tool 2012 (SWAT2012) offers four sediment routing methods as optional alternatives to the default simplified Bagnold method. Previous studies compared only one of these alternative sediment routing methods with the default method. The proposed study evaluated the impacts of all four alternative sediment transport methods on sediment predictions: the modified Bagnold equation, the Kodoatie equation, the Molinas and Wu equation, and the Yang equation. The Arroyo Colorado Watershed, Texas, USA, was first calibrated for daily flow. The sediment parameters were then calibrated to monthly sediment loads, using each of the four sediment routing equations. An automatic calibration tool-Integrated Parameter Estimation and Uncertainty Analysis Tool (IPEAT) - was used to fit model parameters. The four sediment routing equations yielded substantially different sediment sources and sinks. The Yang equation performed best, followed by Kodoatie, Bagnold, and Molinas and Wu equations, according to greater model goodness-of-fit (represented by higher Nash–Sutcliffe Efficiency coefficient and percent bias closer to 0) as well as lower model uncertainty (represented by inclusion of observed data within 95% confidence interval). Since the default method (Bagnold) does not guarantee the best results, modelers should carefully evaluate the selection of alternative methods before conducting relevant studies or engineering projects.