Prediction of sediment erosion after dam removal using a one-dimensional model

Abstract

Abstract The accurate prediction of sediment erosion after dam removal is critical to quantifying the impact of dam removal on the reservoir and downstream environment. A variety of methods can be used to estimate this impact, and one of the most common is to use a one-dimensional mobile bed sediment transport model. I describe a one-dimensional sediment transport model (SRH-1D) and use it to simulate a laboratory experiment of incision through a reservoir delta deposit. The model allows the user to specify the erosion width through the deposit as a function of the flow rate. The model is shown to predict the vertical incision and downstream sediment load with reasonable accuracy if the erosion width is specified. Sensitivity tests to the transport equation parameters, erosion width, and angle of repose are conducted. The sediment loads exiting the dam are shown to be sensitive to the critical shear stress, but they are relatively insensitive to changes to the erosion width and angle of repose. One-dimensional models are shown to require the specification of the erosion width, but the results are not considered to be extremely sensitive to its value, so long as it is approximately equal to the observed river width under the same flow conditions. Further work on modeling of bank erosion is necessary to more accurately predict the long-term evolution of reservoir deposits.