Macro Landslide Hazard Zonation Mapping Using Univariate Statistical Analysis in a Part of Garhwal Himalaya

Landslide hazard zonation mapping of the Atagad River catchment was carried out using univariate statistical analysis. Geo-environmental factors which control the stability of slope like lithology, slope morphometry, structure, relative relief, landuse and landcover and hydro geological conditions are considered as indexes for statistical analysis. The map was prepared by superimposing the terrain evaluation maps using landslide hazard evaluation factors (LHEF) rating scheme and the calculated total estimated hazard (TEHD). The TEHD indicates the net probabilities of instability and is calculated facet wise. On the basis of the TEHD, five categories of landslide hazard zones have been identified, namely, very low hazard, low hazard, moderate hazard, high hazard and very high hazard. Investigation shows that geology, rainfall and human activities have played considerable role in triggering landslides in this part of Himalaya. In the preliminary stage of geotechnical investigation and watershed management, the landslide hazard evaluation factor (LHEF) rating scheme may effectively be used, as this is an economic and rapid hazard assessment technique.