Using a bed sill as a scour countermeasure downstream of an apron

Abstract

In order to protect hydraulic structures against scouring, engineers have designed and used many different types of countermeasures. In this paper, local scour downstream of a rigid apron using a bed sill is studied. The main objective of the present study was to investigate the efficiency of scour reduction by means of a single bed sill located downstream of the apron as countermeasure, and to evaluate its effectiveness at various distances from the end of the apron. It was found that the maximum scour downstream of the apron reduces up to 95%. Furthermore, variations of the characteristic lengths of the scour hole were investigated. Also, it was observed that completely buried sills may not be useful. Finally, a regression based equation is proposed to predict the shape of the scour hole with the sill. Keywords: Scour, Apron, Bed sill, Protective structures, Maximum scour depth