Land Slides Hazardous Zones By Using Remote Sensing And GIS

ABSTRACT Landslide is one of the major natural hazards that are commonly experienced in hilly terrains all over the world. Landslides are affect at least 15 per cent of the land area of India?an area which exceeds 0.49 million km2. In India the incidence of landslides in Himalayas and other hill ranges is an annual and recurring phenomenon. There is a variation in the degree of landslide incidences in various hill ranges. Many researchers quantified the landslide hazard and risk in these areas, however there is no much studies landslide hazard mitigation planning, environmental and societal related issues. Also the recent numerous landslides/landslip in November 2009 taught a lesson and create need and urgency to address these issues. In this connection the existing landslide hazard scenario, the initiation made on landslide hazard mitigation in the district, the feasibility of cost effective technology for slope stabilization, environmental and societal issues need to be addressed for the Nilgiris district were studied and recommendation were given to over come these issues.There were several causal factors such as excavation of slope at its toe, vertical cutting, loading of the slope at crest, defective maintenance of surface drainage systems and extensive anthropogenic interference. The intense rainfall acted as a triggering factor. The results of tests on soil samples collected at the site indicated that the soil is of clayey sand and has low permeability. As there was no proper subsurface drainage system in place, pore water pressure played a major role in inducing slope instability. The need for detailed geotechnical investigations is emphasized.