Flood Modelling due to Dam Failure Using HEC-RAS 2D with GIS Overlay: Case Study of Karalloe Dam in South Sulawesi Province Indonesia

A dam is one of the water structures that have many benefits for humans. However, flood disasters caused by break may a very bad impact on human life. This study specifically analyzed flooding failure Karalloe in Bone Regency, South Sulawesi Province, Indonesia. For first time, selected discharge used analysis was verified using Creager graph comparing calculated from several synthetic unit hydrograph methods (HSS) with measured automatic level recorder (AWLR) at monitoring point. The due to simulated HEC-RAS 2D combined ArcGIS mapping. calculation results design based rainfall data HSS Nakayasu, ITB I, II, and SCS (HEC-HMS) as well designed showed value which closest Q1000 method. values obtained method Tr (return period) 2 years, 5 10 20 25 50 100 1000 years were 322.70 m3/s, 464.10 560.40 658.40 682.70 787.00 885.70 1202.60 respectively. simulation 22 villages will be affected fastest standby time 12 minutes, namely Lookout Point 7 Paitana Village. result suggests early warning system should installed downstream disaster mitigation adopted applied these threatened area.