Facet Based Landslide Hazard Zonation (LHZ) Maps for the Himalayas: Example from Cfaamoli Region

摘要

The paper discusses the facet based Landslide Hazard Zonation (LHZ) methodology with an example from Chamoli region in Higher Himalayas. It is based on hierarchical classification of terrain into homogenous units called facet (Pachauri 1970,1998; Pachauri and Krishna 1984; Pant and Pachauri 1989; Pachauri, 2001; Wagner 1981; Wagner etal. 1987; Deoja et al. 1991). Facets are essentially slopes of varying degrees mapped at 1:50,000 or larger scales. The weighted rating of parameters like slope angle, distance from ridge and others, is taken into account for arriving at a cumulative score for each slope facet. A landslide hazard zonation map can be prepared with zones of hazard values related to relative intensities, using different colour, pattern or shades. The scheme is suitable for high relief terrain like the Himalayas and the Nilgiri Hill region and application of this work spans the Himalayan terrain of Nepal and Bhutan. The methodology is essentially based on geological parameters and is easy to apply in two steps: I. Classification of terrain, and II, Landslide Hazard Zonation using cumulative scores. It is both cost effective and cheap.