| 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 |
| Year: | 2018 |
| Journal: | Water |
| Volume (Issue): | 10 |
| Pages: | |
| Article ID: | 1053 |
| DOI: | 10.3390/w10081053 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| 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. |
| Calibration Summary: | |
| Validation Summary: | |
| 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. |
| Language: | English |
| Keywords: | Soil and Water Assessment Tool; SWAT; sediment; wetlands; Le Sueur |