River Bed Deformation at Water Intakes

Abstract

The damage of engineering structures in rivers, because of scour (near intakes, pumping stations, bridge structures – abutments, guide banks, dams, etc.) leads to considerable environmental and economical losses. During multiple floods the scour hole parameters, under clear-water conditions, are summed up and increases in time. The differential equation of equilibrium of the bed sediment movement in clear water was used, and a method for calculating the scour development with time at the intakes (abutments, guide banks) during the multiple floods was elaborated and confirmed with experimental data ( Gjunsburgs et al., 2001, 2004). Method for computing equilibrium depth of scour and it’s analysis is presented in this paper.The method based on the conditions that at equilibrium stage of scour the local velocity Vlt becomes equal to critical one kβV0t. According to theoretical analysis, the relative equilibrium depth of scour is depending on flow contraction rate; kinetic parameter of the flow; ratio of the Froude number to the river slope; relative flow depth; dimensionless grain size; stratified riverbed conditions; ratio of the local and critical velocities; side-wall slope, and angle of flow crossing. Keywords: flood, flow, intakes, scour, depth Introductio