Flood Hazard, Vulnerability, and Risk Mapping in GIS

Abstract

Flood is a natural hazard that can make a catastrophic impact on the environment. This study attempts to assess floods’ risk in the city of Omidieh, Khuzestan, Iran. We used a multi-criteria decision-making approach, (i.e, spatial decision support system [SDSS]), geodata analytical process (GAP) in Boolean, AHP, and fuzzy, (BAF) as flood issues techniques in hydrology science. The involving factors from the experts have been rated by using the analytical hierarchy process (AHP). Finally, a GIS-based multi-criteria analysis was performed and the thematic maps were prepared. These maps are standardized by Boolean and fuzzy logic. A criteria tree model has been designed in the ILWIS-GIS software. The ASTER digital elevation model (DEM), slopes, soil, geology, land use, erosion, rainfall, drainage density, and the Normalized Difference Vegetation Index (NDVI) are involving parameters to determine flood hazard areas for vulnerability and risk mapping. The factors such as proximity to urban areas (population vulnerable to floods), villages, utilities, oil pipelines, and finally, gas pipelines are used to generate a map, which indicates vulnerability. The results show that the Aghajari 1, 2, and Meiankuh Omidieh sub-watersheds, and some parts of the Omidieh sub-watershed, covered about 12.45% of the watershed, and they are the most vulnerable areas with a high risk of flood hazards.