RS-CIS BASED LANDSLIDE RISK ASSESSMENT IN PARTS OF DARJEELING HILLS

Abstract

Landslides are one of the indicators of the geomorphologic modifications taking place in this active and fragile Darjeeling Himalayan region. These processes of mass movement and landslides have been constantly modifying the landscape. Therefore, landslide susceptibility zonation (LSZ) becomes important. Landslide risk assessment (LRA) is a key component of landslide studies. The landslide risk can be defined as the potential for adverse consequences or loss to human population and property due to the occurrence of landslides. The LRA can be regional or site specific in nature and an important information for planning various developmental activities in the area. Landslide risk assessment (LRA) is concerned; Landslide risk is considered as a function of landslide potential (LP) and resource damage potential (RDP) and Conventional approach. In this present study, two different approaches namely, (1) LRA using Conventional approach and (2) LRA using fuzzy concept based approach have been developed and implemented to prepare LRA maps of the study area. The study area belongs to Darjeeling district of West Bengal and is bounded by 26° 56' N 2 and 27° 08' N latitudes and 88° 10' E and 88° 25' E longitudes covering an area of about 254 km The datasets used to generate various thematic data layers are remote sensing data- IRS-1C LISS-III multispectral and PAN data, Survey of India topographic maps at 1:50,000 scale and as 1:25, 000, and geological map at 1:326,000 scale and field data on existing landslides. In conventional approach are two input layers, first, LSZ Map (landslide potential)are classified into five zones are VHS, HS, MS, LS and VLS and second, resource category (resource damage potential) map are classified in nine category, that is a habitation (VHDP), road (HDP), agriculture (MDP), tea plantation (MDP), thick forest (LDP), sparse forest (LDP), barren (VLDP), river sand (VLDP) and water (VLDP) are integrated, then generate landslide risk assessment matrix, then generated LRA Map I. Whereas, in fuzzy set-based approach membership values were assigned to hazard zones and categories of resource map, then generate LRA Map II. Using these membership values risk assessment matrix was generated.