GIS-based analytic hierarchy process for flood susceptibility zoning in the coastal lowland: A case study of Saidia City, northeast of Morocco

Abstract

The city of Saidia is a coastal Mediterranean urban lowland characterized by concentrated population, tourism infrastructure, and seasonal watercourses. This combination makes the city exposed to inundation. This study maps and assesses pluvial and fluvial flood susceptibility across the coastal area of the city of Saidia using the analytic hierarchy process (AHP) and geographic information system (GIS). Seven conditioning factors were selected and processed as raster layers including elevation, slope, topographic wetness index (TWI), normalized difference vegetation index (NDVI), distance to rivers, distance to roads, and drainage density. The pairwise comparison matrix obtained through expert judgments produced factor weights dominated by TWI (0.28), distance to rivers (0.20), and slope (0.18). The resulting map assigns 41.91% of the study area to the high and very high susceptibility classes. Moreover, the results suggest that the high and very high susceptibility classes are concentrated along the national road, the Moulouya river estuary, and the northern coastal plain where the urbanization occurs. The findings of this study offer valuable and instrumental planning tools for land use control and drainage prioritisation in the city of Saidia.