GIS-based MCDM – AHP modeling for flood susceptibility mapping of arid areas, southeastern Tunisia

TLDR

Floods are a major natural disaster that cause significant socio‑economic losses. This study aims to produce a flood hazard susceptibility map for the Gabes region using a GIS‑based multi‑criteria decision‑making analytical hierarchy process model. The model incorporates eight factors—elevation, land use/land cover, lithology, rainfall intensity, drainage density, distance to drainage network, slope, and groundwater depth—whose relative contributions are quantified by AHP weighting. Elevation was the dominant factor (22.5 %), with 15 % of the area flooded and a flood hazard index of 6.30; validation showed 74.51 % of observed flood events fell within moderate to very high susceptibility zones.

Abstract

Floods are considered as a major natural disaster due to their devastating effects that lead to socio-economic losses. The present study is an attempt to prepare a flood hazard susceptibility map of the Gabes region using 'multi-criteria decision making – analytical hierarchy process' model in geographic information system environment. Eight factors have been used in the flood modeling: elevation, land use/land cover, lithology, rainfall intensity, drainage density, distance from the drainage network, slope, and groundwater depth. The impact of each factor contributing in the flood risk was examined by weights using analytical hierarchy process method. The results obtained shows that the most prominent flood occurrence factor is the elevation (22.5%), around 15% of the total area is flooded and the flood hazard index is equal 6.30. The validation of results by a susceptibility zones histogram showed that 74.51% of the observed flood areas are mainly concentrated in a moderate to very high susceptibility zone.