SERC FLOOD CHANNEL FACILITY - SKEWED FLOW EXPERIMENTS

This article describes experiments carried out on a skewed compound channel in the SERC Flood Channel Facility operated at Hydraulics Research Ltd, Wallingford, England. The project is one of a coordinated group of four being run simultaneously by U.K. University research groups into the hydraulics of overbank river flow. It examines the interactive cross-flows that occur between floodplain and main channel when the two are not parallel. The project was designed to prepare the way for a later examination of overbank flow in meandering channels. Results show that the velocity distribution both in the main channel and over the two floodplains is distorted by this cross-flow, as is also the boundary shear stress distribution. The momentum equation is used to analyse the forces acting on the flow both for the whole cross section and also for the subunits comprising the floodplains alone. The apparent shear force at the floodplain longitudinal interface is isolated from the momentum transport effects of the cross-flow and compared with the comparable term in the prismatic compound channel case. Tentative proposals are made for the secondary circulation structure in the main channel.