Dam-Break Assessment of Ciawi-Sukamahi Parallel Dry Dams by Using HEC-RAS

This research intends to evaluate dam-break in CIawi and Sukamahi dams. Both CIawi and Sukamahi dams are dry dams with parallel position. The concept of flood control pattern in Ciawi and Sukamahi dams is in the beginning of rainy season and the elevation of water level in both dams must be in low elevation. It is possible by the available tunnel to flow water into both dams. If the failure of Ciawi-Sukamahi parallel dry-dams happens together, it needs some observations for anticipating it. The methodology consists of data collecting; literature study of related previous research; analysis of the PMP (Probable Maximum Precipitation) rainfall by using Isohyet and Hersfield methods, design flood by using HEC-HMS, dambreak by using HEC-RAS, then the losses of parallel dams-break by using InaSAFE method. The research result shows that the potency of Ciawi-Sukamahi parallel dry dams will break in the worst scenario that is piping in Ciawi dam with PMF discharge of 1,389 m³/s and in Sukamahi dam with PMF (Probable Maximum Flood) discharge of 254 m³/s and causes the inundation of 50.9 km² that spreads in 8 cities/ regencies. The result is hoped as the consideration to the stakeholder related with flood mitigation due to the simulation of the dam-break potency of Cimahi-Sukamahi parallel dry dams.