Two-dimensional dam break modelling of Beris Dam using HEC-RAS

Abstract

Dam is built for various functions such as water supply, flood and sediment control, electricity generation and irrigation. Floods due to dam breaches create higher peak flows than floods produced by heavy rainfall. When a dam collapses, the stored water may cause devastating catastrophe towards downstream areas by causing fatalities and property damages. The aim of this study is to perform a two-dimensional dam break modelling of Beris Dam due to probable maximum flood (PMF). The HEC-RAS software was used to predict the breach outflow’s hydrograph and produce the flood inundation and velocity map. Dam breach parameters were calculated using Froehlich and MacDonald and Langridge-Monopolis (MDLM) equations. A 4-day simulation conducted showed that a breach was initiated at almost 10.35 am, 34 hours and 35 minutes after the PMF scenario. Peak discharge during the PMF failure is 10,745.12 m3/s at 12.45 pm the next day which is after 2 hours and 10 minutes of dam breach initiation. Felda Lubuk Merbau, Kampung Betong, Jeniang, Padang Serai and Kota Kuala Muda are among the areas affected by the simulated Beris Dam break. Information obtained on flood velocity, depth and arrival time are useful to local authorities in order to respond effectively and immediately in the event of dam break.