SWAT Literature Database for Peer-Reviewed Journal Articles

Title:Reducing high flows and sediment loading through increased water storage in an agricultural watershed of the Upper Midwest, USA 
Authors:Mitchell, N., K. Kumarasamy, S.J. Cho, P. Belmont, B. Dalzell and K. Gran 
Volume (Issue):10 
Article ID:1053 
URL (non-DOI journals): 
Broad Application Category:hydrologic and pollutant 
Primary Application Category:wetland effects and/or processes 
Secondary Application Category:sediment loss and transport 
Watershed Description:Le Sueur River, a tributary of the Minnesota River located in southeast Minnesota, U.S. 
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General Comments: 
Abstract:Climate change, land clearing, and artificial drainage have increased the Minnesota River Basin’s (MRB) stream flows, enhancing erosion of channel banks and bluffs. Accelerated erosion has increased sediment loads and sedimentation rates downstream. High flows could be reduced through increased water storage (e.g., wetlands or detention basins), but quantifying the effectiveness of such a strategy remains a challenge. We used the Soil and Water Assessment Tool (SWAT) to simulate changes in river discharge from various water retention site (WRS) implementation scenarios in the Le Sueur watershed, a tributary basin to the MRB. We also show how high flow attenuation can address turbidity issues by quantifying the impact on near-channel sediment loading in the watershed’s incised reaches. WRS placement in the watershed, hydraulic conductivity (K), and design depth were varied across 135 simulations. The dominant control on site performance is K, with greater flow reductions allowed by higher seepage rates and less frequent overflowing. Deeper design depths enhance flow reductions from sites with low K values. Differences between WRS placement scenarios are slight, suggesting that site placement is not a first-order control on overall performance in this watershed. Flow reductions exhibit power-law scaling with exceedance probability, enabling us to create generalized relationships between WRS extent and flow reductions that accurately reproduce our SWAT results and allow for more rapid evaluation of future scenarios. Overall, we show that increasing water storage within the Le Sueur watershed can be an effective management option for high flow and sediment load reduction. 
Keywords:Soil and Water Assessment Tool; SWAT; sediment; wetlands; Le Sueur