Flash Flood Hazard Mapping Based on Analytic Hierarchy Process for a Complex Terrain: A Case Study of Chu Lai Peninsula, Vietnam

Flooding prediction for a large scale area has been popularly carried out, nevertheless flood hazard assessment for a small, complex terrain for planning industrial constructions needs more detailed studies. This study aims to: (1) determine forcing factors and their roles in the flood hazard using the Analytic Hierarchy Process (AHP), and (2) generate the flood hazard map using spatial analysis in Chu Lai peninsular, Vietnam. The study shows that 6 important forcing factors on flood hazard include drainage density, infiltration rate, soil saturation, elevation, slope, and land cover. The factor which most impacts on the flood hazard is the elevation with the detected weight of 0.438. The infiltration rate plays the least importance with a weight of 0.066. Consequently, a flood hazard map is generated with 5 levels very low, low, medium, high, and very high hazard of flood. The very high hazard occupies 7.16% area of the peninsula focusing on the regions covered by concrete surface, permanent and temporal water cover, bare soil, and very low slope from 0° to 8°. The map provides critical information to make a plan for one of the most important industrial complexes in the center of Vietnam.