Landslide Hazard Zonation Mapping using AHP and GIS Techniques for the Valapattanam River Basin, North Kerala, India

Ajayakumar A^a , Anandhu Sathish ^b, Rajesh Reghunath^a, Anoop S^b

^a,Department of Geology, University of Kerala, India, ^bDepartment of Geology, University college, University of Kerala, India

Abstract

Landslides are recurrent natural hazards in the Western Ghats of Kerala, frequently intensified by monsoon rainfall and human-induced land modifications. This study develops a detailed Landslide Hazard Zonation (LHZ) map for the Valapattanam River Basin, a region with limited site-specific assessments, using an integrated Analytical Hierarchy Process (AHP) and Geographic Information System (GIS) approach. Nine conditioning factors-geology, geomorphology, slope, land use/land cover (LULC), soil, drainage density, lineament density, road density, and rainfall-were weighted through pairwise comparison and consistency checks. Weighted overlay analysis generated five susceptibility zones ranging from very low to very high hazard. Results reveal that approximately 50% of the basin falls under moderate hazard, 32% under high hazard, and 1% under very high hazard. Validation using a Receiver Operating Characteristic (ROC) curve achieved an accuracy of 91.3%, confirming the robustness of the model. The findings highlight that steep slopes, fragile lithology (charnockite and peninsular gneiss), high lineament and road density, and altered land cover are the key drivers of slope instability. The study provides crucial insights for regional planning, disaster risk reduction, and sustainable land management in a landslide-prone tropical river basin.

Keywords

Landslide hazard zonation; AHP; GIS; ROC; Valapattanam River Basin

How to Cite

A, A., Anandhu Sathish, Rajesh Reghunath, & Anoop, S. (2026). Landslide Hazard Zonation Mapping using AHP and GIS Techniques for the Valapattanam River Basin, North Kerala, India. Journal of Integrated Earth Sciences, 1(1), 8–21. https://doi.org/10.5281/zenodo.18538456