Landslide Hazard Zonation in the Alaknanda River Basin using Innovative Techniques

Globally, landslides are one of the most common natural catastrophes. Extreme precipitation such as cloudbursts is a primary factor causing a landslide in the Indian Himalayan region. Identification of potential locations vulnerable to landslides using hazard zonation mapping may play an important role in reducing their occurrences by implementing the best engineering measures. This study uses satellite images and Geographic Information System (GIS) to prepare a landslide hazard map for the Alaknanda River (AR) basin in Uttarakhand (India). The river basin elevation ranges between 600 and 7800 m above m.s.l. with a mean slope of 31.5 degrees. This river basin has experienced several cloudbursts and flash flood events that initiated landslides causing significant loss of life and property. This study uses the Analytical Network Process (ANP) to assess the AR basin’s susceptibility to landslides, rock falls, and mudslides. The contributing factors considered are elevation, slope, aspect, curvature, lineament, land use land cover, soil, geomorphology, drainage density, and rainfall. The affected locations in the past are identified and validated from the historic landslide inventory available from the Geological Survey of India. The results are classified into several qualitative tiers such as very high, high, moderate, low, and very low hazard zones. It is observed that the landslide-affected districts are Chamoli, Rudraprayag, Bageshwar, and Pithoragarh. It is hoped that such mapping will help decision-makers in risk management, disaster response, and emergency services planning.