Local Scour Upstream of a Slit Weir: Ordinary Differential Equation–Based Model under Steady and Unsteady Flow Conditions

Abstract

Time-varying scouring upstream of a sediment release gate during a flood needs to be accurately predicted for reducing sedimentation around a water intake. This paper presents an ordinary differential equation–based model for computing time variation of scoured volume and maximum scour depth upstream of a slit weir for steady and unsteady flow. The model is based on the sediment continuity equation and sediment entrainment volume from a scour hole. There are some hypotheses in the model, and these hypotheses were examined by carrying out (1) 45 runs of scour inception tests, (2) 36 runs of numerical tests using computational fluid dynamics, and (3) 33 runs of physical scour tests measuring time variation of scoured topography. The model was validated with the scour tests for steady and unsteady flow conducted in the present study in addition to those reported in different research. The model was found to agree well with the data of time variation of the scoured volume and maximum scour depth, allowing for using a consistent numerical scheme irrespective of steady or unsteady flow condition.