Flood hazard zoning in Ngan Sau, Ngan Pho river basin, Ha Tinh province using GIS and analytical hierarchical process

This paper introduces the AHP method integrated with GIS technology to provide information for flood hazard analysis in the Ngan Sau and Ngan Pho river basins. The factors ìnluencing the occurrence of floods in a study area include slope, rainfall, drainage density, soil, relative slope length, and land cover. These data are used for establishing a flood hazard zone map in a GIS environment. The obtained results indicate that the two main causes of flooding are rainfall and slope with weights of 45% and 25.5%, respectively. The resultant map has shown about 82.78% of the total catchment area is having a high and very high probability of flood and areas under high flood hazard only covers 17.22% of the study area. The validation of the flood hazard zone map was conducted based on flood evens in the field. The results showed that the AHP technique and GIS are reliable methods for the assessment of the flood hazard potential, specifically in spare-data regions.