Advances in Modeling Cohesive Sediment Detachment and a Process-based Method for Stream Restoration to Determine Sediment Loads

Abstract

The majority of sediment loads to surface waters often originate from streambanks causing water quality issues in streams and reservoirs. Streambank erosion is a complex cyclical process involving subaerial processes, fluvial erosion, seepage erosion, and geotechnical failures and is driven by several soil properties that themselves are temporally and spatially variable. Therefore, it can be challenging to model streambank retreat. However, the ability to model streambank erosion has many important applications including the design of mitigation strategies for stream restoration practices. In order to account for the complicated nature of streambank retreat, process-based models that incorporate the forces and moments driving and resisting erosion are needed. However, several questions related to erosion processes still need to be researched in order for the models to be a more useful tool in the stream restoration community. The purpose of this research was to answer some of these lingering fundamental questions including: (i) are nonlinear mechanistic detachment models more appropriate than the traditional empirical approaches for quantifying sediment detachment due to fluvial forces and (ii) how can typical restoration practices be modeled in commonly used process-based models, such as the bank stability and toe erosion model (BSTEM), to estimate sediment load reductions to surface waters? Additionally, previous peer reviewed research utilizing BSTEM was analyzed to demonstrate current uses of the model and suggest further research needs.