FLOODPLAINS MODELLING DUE TO DAM BREAK

The prediction of floodplains caused by dam break is very important to discuss for future planning and decision making for contingency evacuation planning and real time flood forecasting. The objectives of this study are (1) to determine the propagation of flood in the study area, in terms of water depth and velocity magnitude, and (2) to identify the potential area of high risk of flooding. The comparison of results using one point source input flood discharge (total discharge) and flood hydrograph have been carried out. The floodplain is simulated using software called CCHE2D_FLOOD model. A flood hydrograph due to dam break at Durian Tunggal Dam is used as a model parameters input. The simulation results showed that the higher flood depth for discharge hydrograph was 6.8 m, a bit lower than the sudden failure, which was 7.1 m. Meanwhile, the highest velocity predicted was 7.7 m/s. The total flooded area was approximately 48 km 2 and the potential risk happened at the residential area.