Unravelling the role of landslide causative factors on landslide susceptibility along NH 505 using Analytic Hierarchy Process (AHP) in geospatial environment

Abstract

Landslides are critical hazards which disrupt the infrastructure and transport network in hilly terrains, leading to the loss of lives. In hilly regions where the slopes are highly steep, the major national highways are highly susceptible to slope failures. National Highway 505 is a vital link between Lahaul and Spiti, which faces consistent slope failures due to complex terrain and hydro-geological characteristics. The steep slopes, fragility of the rock structures, heavy precipitation, snowmelt, and anthropogenic activities make this region highly prone to landslides. A landslide susceptibility map may help in identifying the landslide potential along the national highway. This study aims to use the Analytic Hierarchy Process for preparing the landslide susceptibility map along the NH 505 in the Geographic Information System (GIS) environment. Ten conditioning factors, including slope, lithology, land use/land cover, and geomorphology, were integrated using the Analytic Hierarchy Process (AHP) in a GIS environment. The results show that 29.82% of the study area has very high landslide susceptibility, while 36.9% of the study area has high landslide susceptibility. The results of the study are validated using a receiver operating characteristic (ROC) curve, which showed a prediction rate of 0.817. The output of the study can be used as a critical tool for highway planning and disaster risk reduction along the national highway.