Live-Bed Scour at Submerged Weirs

Abstract

AbstractWeirs or bed sills are low-head hydraulic structures used for bed stabilization, raising upstream water level, and reducing flow velocity. During high-flow events, the weir is fully submerged in the river and scouring occurs both upstream and downstream of the weir. For a fully submerged weir, the scour mechanism around the weir is dependent on approach flow intensity (clear-water scour conditions or live-bed scour conditions) and flow regimes (surface-flow regime or impinging-jet regime) over the weir. The fast evolution of underwater mobile topographies and propagating bedforms increase the complexities of the scour process and the difficulties for scour measurement at the submerged weir under live-bed scour conditions. This paper develops a measurement and data-processing technique for the study of scour at submerged weirs under extreme measurement environments and investigates the scour process both upstream and downstream of submerged weirs under live-bed scour conditions. The experiments are...