Dam Break Flood Mapping and Analysis Using Open Source GIS Tool and Data

Abstract

The impact of climate change may influence on extreme weather conditions and may lead to high intensity precipitation, which will impact on huge structures such as dam. Although risk mitigation and protection of dams from advanced technical expertise have been reviewed regularly, a maximum non-risk guarantee is not achievable, and incidents may occur due to water that usually flows over a spillway and high-speed discharge or unexpected peak discharge. Hence, the immediate impact of dam failure is on the population at risk near the downstream area. This study evaluates the impact of dam break scenario under probable maximum precipitation (PMF) condition at Puah hydropower dam. The aims of this study are to determine the potential risk area at downstream and to assess the flooding impact on population and public facilities due to dam break event. Integration of an open source GIS tool, Google Satellite Image, Open Street Map, and flood hazard map derived from hydrodynamic model has been used to efficiently analyse the impact of dam break flood by using spatial analysis method, and to generate possible evacuation route network. Analysis has estimated that 187,796 people at risk, 3,177 km of road, 2-unit hospital and 76 amenities (mosque and school) will be impacted. This study portrays the possibility of using open source data and tool as an alternative for emergency preparedness application. The method used in this study could be adopted to other area of interest and disaster event, helping the local authorities for disaster emergency preparedness and early warning systems focusing on rescue work if disaster occurs.