Case Study: Sediment Transport Simulation at Munds Draw Watershed

This paper reported a case study that applies the SWAT+ watershed model to assess flow and sediment transport in the Munds Draw watershed aiming to evaluate the effectiveness of erosion control measures on sediment load reduction. We developed SWAT+ model for the watershed using three fine delineations with the number of subbasins as much as 4500. The simulation period is from 1979 to 2014 totaling 36 years. To evaluate the impacts of grade control structures, SWAT+ model was developed for a small watershed with 94 erosion control structures. Two simulations were carried out: one is for the entire 2010 assuming the structures were in place. SWAT+ model were carried out with and without the structures. Results showed there are not much differences of simulated water yields and stream flow discharge using three different delineations, but the results of sediment load are different. For seven design rainfall events, we found erosion control structures slightly retained the flow with the maximum reduction of 0.35% at 2-year design storm, and 0.01% reduction at 500-year design storm. The sediment reduction by the structures are 27.56% for 2-year design storm, and 15.61% reduction for 500-year design storm. The reduction of sediment load is considerable high at low intensity event. SWAT+ model is effective in assessing flow and sediment transport in ungagged watersheds. However, due to the simplification of physical processes, the results need further calibration and verification using experimental data.