Slope Stability and Damming Probability Assessment of a Recurrent Landslide in Garhwal Himalayas

Landslides are one of the most frequently occurring geological hazards in the mountainous areas, accounting for substantial environmental and economic damages. Considering the severity of landslides and their possible consequences, the present study investigates a recurrent landslide located at Bhatwari, Uttarakhand. Stability grade and associated risks of the studied landslide slope were determined using geospatial and geotechnical approaches. For stability assessment, rock mass classification and numerical methods have been employed. Factor of safety (FoS) values are determined for static and pseudo-static loading conditions. Some of these analyses also incorporate the effect of pore water pressure. Further, different geomorphic indices, such as the Morphological Obstruction Index (MOI), Hydro-morphological Dam Stability Index (HDSI), and Dimensionless Blockage Index (DBI) were used for checking landslide dam development potentiality in the Bhagirathi River. The results suggest that the slope is critical for simulated scenarios and indicate that slope-forming materials may fail due to triggering factors like extreme rainfall and/or earthquake events. However, the landslide damming probability assessment reveals that dam formation has negligible possibility and even if it develops, then it may not sustain for a longer time. Reactivation of the slide will definitely damage the NH-108, thus the slope needs immediate attention for implementation of suitable stabilization measures.