Title: Scour evolution under flood events at engineering structures in flow

Abstract

The mutual multiple floods and layering of the riverbed impact on scour hole evolution near structures in flow can be reason of failure because of scour. Although the problem is very topical, the mutual impact floods and the stratified riverbed layers on the scour at the structures has not been studied well. The aim of the laboratory tests with was to study the scour processes, the effect of the flow parameters , the contraction rate of the flow, grain size of the bed material, steady or unsteady flow conditions, and the scour evolution with time. The differential equation of equilibrium of the bed sediment movement in clear water and unsteady flow conditions was used to create a model for calculating the depth, width and volume of scour hole at the engineering structures in flow is elaborated. Based on the agreement of experimental and calculated results, the computer program was carried out to model time-dependent scour development during multiple floods with different duration, probability, frequency and sequence. The analysis of the influence of multiple floods showed that, with less probability, increased duration and frequency of the floods, and certain sequences of different probability, the scour depth, width and volume increases. It was confirmed that the scour depth evolution in floods depends multiple floods of different probability, sequence, duration, frequency, sequence and river bed parameters near the water engineering structures in flow.