Relationship between Selected Physiographic Features and Landslide Occurrence around Four Hydropower Projects in Bhagirathi Valley of Uttarakhand, Western Himalaya, India

Abstract

The Himalayan mountain range is an internationally recognised landscape but one under increasing developmental threat. The lower Himalayan region possesses immense potential for hydropower generation but is also highly susceptible to tectonic deformation and mass wasting, especially landslides. Susceptibility to landslides increases markedly with human activity, especially large scale developmental projects. The impacts of massive hydropower plant construction in the Bhagirathi Valley, Uttarkhand, India on the generation of landslides are the focus of this study. Whilst many positive impacts derive from such projects, devastating negative impacts also accrue. The frequency and characteristics of land sliding within the sphere of influence of the construction sites of the various hydropower plant components were investigated. Landslide frequency was related to parameters of geology, prior land use, drainage density, slope steepness and location in terms of construction aspect. Landslide frequency was found to be greatest in gneissic terrain as well as on previously agricultural and forested lands. Statistical analysis revealed significant relationships between landslide frequency with slope and, frequency with construction aspect, especially the construction of access roads. As with other studies, road construction is the key initiator of land sliding due to slope over steepening and the indiscriminate dumping of debris. The study concludes with recommendations for reducing the frequency and magnitude of mass wasting in this environment.