Influence of Using Floor Jets on the Local Scour Downstream Fayoum Type Weir

Abstract

Local scour downstream hydraulic structures may cause damage or complete failure of these structures. In this paper, an experimental study was carried out to investigate using floor water jets as a mitigation measure to minimize the local scour downstream stilling basin and to clarify the best arrangement of these jets. Different cases were established during this study including different flow discharges, tail water depths and floor jet locations. A base case without using water jets was included to estimate the influence of using suggested water jets arrangements. Additional four cases for various jets arrangements were established and studied. Obtained results were analyzed and graphically presented. The optimum design was easy to be used for increasing the performance of stilling basin. The results indicated that the optimal arrangement of floor jets was the case (D), where the last three rows of floor jets were used. This optimum design results in a reduction in maximum scour depth ranged from 44.53 % to 76.15 % and reduction in scour length ranged from 25.00 % to 71.93 % compared to the base case.