Landslide susceptibility and vulnerability assessment using GIS–AHP in the highland of Wayanad, Western Ghats, India

Landslides are among the most frequent and damaging natural hazards in the ecologically fragile and topographically varied Western Ghats of Kerala. The Thirunelly region in Wayanad district, characterized by steep slopes, fractured lithology, loose lateritic soils, and intense monsoonal rainfall, is particularly susceptible to such events. This study systematically assesses these conditions by integrating the Analytic Hierarchy Process (AHP) with Geographic Information Systems (GIS) to produce a coherent village-level landslide susceptibility and vulnerability evaluation. Twelve thematic layers comprising slope, rainfall, geomorphology, geology, drainage density, lineament density, land use/land cover (LULC), soil type, elevation, NDWI, NDVI, and aspect were selected based on literature review and expert input for susceptibility analysis. Using Saaty’s pairwise comparison matrix, weights were assigned to each criterion and spatially integrated in a GIS environment. The resulting susceptibility map identified approximately 34.45 sq km in the central and southwestern parts of the study area as highly susceptible, demonstrating strong spatial coherence with known terrain instabilities supported by an AUC–ROC value of 0.816. The vulnerability assessment was conducted focusing on anthropogenic exposure using three indicators: buildings, roads, and agricultural land. These were similarly weighted through AHP and validated using a Consistency Ratio (CR < 0.1). The vulnerability map identifies 66 km 2 as very high vulnerability, and its ROC curve produced an AUC of 0.739, indicating moderate predictive performance. This study highlights the utility of AHP–GIS-based multi-criteria decision-making frameworks in assessing landslide hazards in complex mountainous terrains.