IDENTIFICATION OF LANDSLIDE PRONE ZONE IN COONOOR TALUK USING REMOTE SENSING AND GIS

Landslide is one of the major natural hazards that are commonly experienced in hilly terrains all over the world. It is more common too in hilly areas of India, especially in Coonoor Taluk in Nilgiris District of Tamil Nadu, South India. Total area of the Taluk is 232.7km2, and it contains 8 revenue villages. The latitude and longitude extension of the study area is 11.24535N to 11.39855N and 76.67181E to 76.87873E respectively. As of 2001 India census, Coonoor had a population of 50,079. Landslides are one of the most common natural as well as man-made hazards in mountainous terrain. It involves movement of a mass of rock, debris, or earth down a slope, under the influence of gravity. Slope instability, in general, is a product of a number of factors such as geomorphological, hydrological, and geological attributes; modifications of geodynamic processes; frequency and intensity of precipitation; human activities; vegetation and land-use practices.In order to identify the land slide prone areas in Coonoor Taluk, this study has been carried out using remote sensing and GIS techniques. Landuse and base maps were prepared by using Quantum GIS by using Heads-up digitization method. GIS (Geographical Information System) and remote sensing are recent most techniques to identify landslide and mapping. Identifying landslides prone zone by using topographic sheets, ASTER (Advanced Space borne Thermal Emission and Reflection Radiometer) DEM (Digital Elevation Model) data and Aster Terra look data are more of accurate. GIS technique is employed in this study to integrate the aforementioned instability factors. The intersection of these factors using technique enables users to classify an area into zones of varying degrees of instability. Slope map was created by using ASTER DEM data in GRASS GIS software environment. Slope is an important criteria for potential Landslide development. Slope angle has been classified into six classes: plain (0%–20%), gentle slope (20%–30%), moderate (30%– 40%), fairly inclined (40%–50%), inclined (50%–60%), and very inclined (60%–70%). For stability of hill slopes, a landslide hazard zonation map was prepared so as to select proper road alignment and regional planning in order to provide quantitative measures to be taken by the authorities in unstable, hazard-prone areas.

Keywords:

LANDSLIDES , SLOPE MAP , ASTER IMAGE , DEM , OPEN SOURCE GIS