Perbandingan gerusan pada bendung di hilir kolam olak tipe vlughter dengan proteksi riprap dan groundsill

Abstract

Hydraulic jump is a phenomenon occurring in channels due to a change in flow from supercritical to subcritical. This phenomenon can be found in dam structures where the stilling basin becomes a crucial part of the dam that needs to be well-designed to dissipate the energy resulting from the hydraulic jump. However, downstream issues in dam bodies also often arise in the form of erosion in the downstream part of the dam's stilling basin (endsill). Therefore, this study focuses on the investigation of erosion protection downstream of the dam to determine the optimal protection type to reduce erosion in the downstream area. The erosion study was conducted at the Hydraulics Laboratory, Department of Civil Engineering, Universitas Islam Indonesia, using a sluice gate model with a vlughter-type stilling basin subjected to three variations of the upstream flow depth (h0). The flow was allowed to run for 60 minutes in each variation. The study involved two experimental conditions: one without protection and the other with protection using riprap and groundsill. The channel bed material used was fine sand (with a sieve diameter of 7mm) with a thickness of 5 cm along the channel. The experimental results indicate that the magnitude of erosion is influenced by the flow velocity and upstream flow depth (h0) and is also affected by gravity (Froude number) and Reynolds number. Based on the observations of erosion experiments in the downstream stilling basin, it can be concluded that using riprap protection is more effective in reducing erosion compared to groundsill protection.