Landslide susceptibility mapping of proposed reservoir of Budhigandaki Hydropower Project and its adjacent region

Abstract

Detailed geological study and landslide susceptibility mapping are crucial aspects and critical components of any engineering project in tectonically active Himalayan region. The study area was characterized by the rocks of Nawakot complex with Lower Nawakot Group which comprises Kuncha Formation, Fagfog Quartzite, Dandagaon Phyllite, Nourpul Formation, Purebesi Quartzite and Dhading Dolomite and Upper Nawakot Group comprises the Benighat Slate only. Landslide susceptibility mapping was carried out by Weight of Evidence method and Frequency Ratio method using the combination of remote sensing and detailed engineering geological investigation of field. Data obtained from these methods were integrated and analyzed in Arc Map 10.8. During study sixteen landslide triggering factors were analyzed. These factors are slope, aspect, stream power index, topographic wetness index, distance from stream, normalized difference vegetation index, land-use and land cover, distance from shear zone, rainfall, plan curvature, profile curvature, distance from road, lithology, elevation, sediment transport index, terrain ruggedness index and all these factors were integrated into a map. The map was validated with an Area under curve (AUC). The Success Rate curve shows 72.54% accuracy for Frequency Ratio method and 76.04% for Weight of Evidence method.