Statistical analysis of Landslide in South district, Sikkim, India: using Remote Sensing and GIS

Landslides are among the most costly and damaging natural hazards in mountainous region, triggered mainly under the influence of earthquakes and/or rainfall. In the present study, Landslide Hazard Zonation (LHZ) of South district, Sikkim State was carried out using Remote Sensing and Geographic Information System (GIS). Various thematic layers namely slope, photo-lineament buffer, thrust buffer, relative relief map, geology and land use / land cover map were generated using remote sensing data and GIS. The weighting rating system based on the relative importance of various causative factors as derived from remotely sensed data and other thematic maps were used for the LHZ. The different classes of thematic layers were assigned the corresponding rating value as attribute information in the GIS and an ‘‘attribute map’’ was generated for each data layer. Each class within a thematic layer was assigned an ordinal rating from 0 to 9. Summation of these attribute maps were then multiplied by the corresponding weights to yield the Landslide Hazard Index (LHI) for each cell. Using trial and error method the weight-rating values have been re-adjusted. A LHZ map was prepared showing the five zones, namely ‘‘very low hazard’’, ‘‘low hazard’’, ‘‘moderate hazard’’, ‘‘high hazard’’ and ‘‘very high hazard’’ by using the ‘‘slicing’’ operation.