TWO-DIMENSIONAL SIMULATION OF SULTAN ABU BAKAR DAM RELEASE USING HEC-RAS

Abstract

Dams are constructed as water storage to compensate for fluctuations in the catchment area and to generate electricity. However, uncontrollable amount of discharges released from the gated spillways of the dam would impact the downstream area. On October 23, 2013, floods occurred in downstream of Sungai Bertam probably due to a huge volume of discharges were released from Sultan Abu Bakar (SAB) dam. Impacts of that flood, three people were confirmed dead and nearly 100 houses destroyed or under water while over 100 vehicles badly damaged. Thus, a study on various maximum discharges released on the behavior of flow along 4 km and 200 m width downstream river was conducted. The objectives in this study were to evaluate flood inundation area and to produce flood hazard map which able to predict risk area of flooding. The computer simulation was done to analyze various maximum discharges released from the gated spillway by using two dimensional HEC-RAS which is constructed by US Army Corp with the aid of a high resolution of Digital Elevation Model (DEM) data. The amount of water release used in the simulation were 10, 25, 30, 50, 100, 230 and 300 m³/s based on recommendation dam release by Tenaga Nasional Berhad (TNB). The result shows that the safest maximum release was 50m³/s in order to avoid inundation happen. This study will also help authorities to control the amount of maximum discharge level allowed from the dam. Besides, it can give awareness to local residents of risk area on flood wave travel time.