Evaluating coastal erosion vulnerability of Cox's Bazar coastline using Analytic Hierarchy Process (AHP) and GIS technique

Coastal erosion is a significant critical issue that is environmentally challenging and threatens the coastal ecosystems and the livelihoods of local residents living in the coastal zones in the world. The study was conducted on the world's longest coastline in Cox’s Bazar, Bangladesh to evaluate the coastal erosion vulnerability (CEV) with the help of the Analytic Hierarchy Process (AHP) and GIS techniques. Nine key natural-anthropogenic factors contributing to coastal erosion were identified and weighted using the AHP and 100 Key Informants Interview (KII) survey data. All the key informants were living in the study area. Thematic layer of CEV was produced through spatial weighted overlay of the factors weight. The study found that storm surge, sea level rise, and human interference had the criteria weights 20%, 17.8%, and 15.6%, respectively, contributing to CEV. The spatial distribution of vulnerable zones represented that the northern and middle areas of the coastline were highly vulnerable due to storm surges, human density, rising sea levels, etc., and the southern areas were lowly vulnerable to erosion. It indicates that 47.65% of the total area (72.46 km2) was highly vulnerable to coastal erosion, 25.09% was moderately vulnerable, and 27.26% was low vulnerable to erosion. The accuracy assessment using 200 ground truth samples revealed the true positive rate of 74.48%, indicating strong performance of AHP-GIS approaches in identifying CEV. Policymakers can use the findings of this study to formulate efficient coastal management strategies and evidence-based policy interventions to reduce the socio-environmental impacts of coastal erosion.