Assessing the efficacy of tributary upstream meander restoration on downstream landscape stability through computational modelling

Meander restoration has become a commonly advocated solution in flood-prone or ecologically degraded river networks. The long-term impact of such measures on the stability of the landscape at the catchment scale beyond the implementation site itself is critical to project success and for sustainable catchment management and needs to be considered by all stakeholders. It is challenging, however, to predict the overall contribution of meander restoration in stabilising the lower catchment and to make reasoned assumptions about the optimal placement, scale, and interconnected benefits of restoration projects based on an analysis of real-life cases due to the complexity and uniqueness of each catchment’s hydrology and the size and cost of such projects. Meanwhile, digital models can be utilised to test a wide variety of hypothetical futures so that the potential impacts of meander restoration can be understood in advance and limited resources can be better allocated to promote effective kinds of projects. In this study, computational modelling is employed to model the impacts of various upstream meander restoration scenarios on the downstream landscape due to erosion and deposition activities in northern England’s River Don catchment. The results indicate that compared to a baseline scenario, river restoration in tributaries effectively reduces downstream main channel sediment discharge and lateral migration activities. Upstream restoration projects prevent watershed deterioration more effectively than downstream projects. Clustering projects close to one other is more effective in reducing valley lateral erosion and deposition, as well as channel loading, compared to having projects dispersed across multiple tributaries.