Understanding the dynamics of gravel dispersal following augmentation in impounded rivers: Research project

The downstream transport of river gravels is interrupted by dams causing a range of ecological impacts. To offset gravel augmentation is a river restoration practice. This pioneering research is focussing on understanding the dynamics of gravel transport in impounded rivers, especially steep upland boulder bedded channels, and implications for habitat creation. The research is being supported by South West Water, Wessex Water and Westcountry Rivers Trust with instrumented reachs below the Avon Dam in Devon and Sutton Bingham reservoir in Somerset, England. The research started in 2016 and is ongoing given that large infrequent floods are of paramount importance in gathering robust and representative data to understanding the long-term dynamics of movement. Novel use is being made of RFID and impact plate technologies and fluvial audits. Tagged rocks suggest that deposition is intrinsically controlled by the fanlike properties of coarse sediment dispersal overlain by local controls provided by in-channel coarse roughness elements, sheltered bank margins and channel curvature. Complementary biological research is currently being undertaken by the University on invertebrate colonisation of newly deposited gravels.