Alluvial processes: physical processes (SR 123)

This report describes work that was undertaken as part of a research programme to improve the understanding of the physics of sediment - related phenomena. The investigations reported here have dealt with frictional resistance and local scour. Desk and laboratory studies have been carried out to investigate the effect of sand-silt mixture and also of bed features on alluvial friction. Two distinct relationship have been observed, one for lower regime and one for upper regime. Desk and laboratory studies have been carried out to investigate the development of local scour with time. This has shown the importance of the flow geometry to model tests and also that later scour may be predicted from initial scour development.