DEVELOPMENT OF INUNDATION RISK MAP FOR THE BA RIVER-DOWN STREAM

Abstract

The flood risk level in the Prime Minister's Decision No-18/2021/QĐ -TTg of April 22th in 2014 which is identified by water and alarm level at hydrology stations, therefore it is not detailed. Because, at the same water level but inundation depth is deferent between regions so inundation risk level is deferent. Beside, at the same inundation depth but socioeconomic is deferent between regions so inundation risk level is deferent too. Therefore, it is needed to develop inundation risk maps for advancing reliability about warning. This research, experimented establishing detail inundation risk level map in the Ba downstream river based on the Decision No-18 and risk index detail based on the IPCC of perspective, the AHP of method. The detail inundation risk index map in the Ba downstream river is established by detail inundation map and sociology survey data. Inundation scenario maps in the Ba downstream river and sociology survey data are combined to establish detail inundation risk level map for 1%, 3%, 5%, 10% flood frequency and dam break of Ba Ha River with design flood, test flood. The results show that the case of dam break then common risk level is level 4, 1% flood frequency then common risk level is level 3 - 4, 3% and 5% frequency then common risk level is level 3, 10% frequency then common risk level is level 2 - 3; risk level in Tuy Hoa city, Son Hoa and Song Hinh district are higher than other areas because exposure of property in hazard or inundation depth is higher.