Experimental study of clear-water contraction scour

Abstract

In this paper, experimental results of clear-water scour on a sand bed under short contractions were studied. Sequences of test runs were performed under clear-water conditions for three different contraction ratios. The outcomes of the experiments were employed to define the effects of various parameters on equilibrium scour depth under clear-water scour conditions. In this work, the precision of three maximum scour depth equations was tested from previous studies for contraction scour cases. Two new analytical equations were proposed to calculate time-dependent scour depth and maximum scour at equilibrium conditions, respectively, from the study. The proposed equations were validated using measurements from the present study as well as from previous literature, and the equations show a reasonable agreement between measured and computed values of scour depth under clear-water conditions in short contraction. The presented equations can be used for studying protection of the submerged portion at a bridge abutment or any similar structure.