Relative effect-based landslide hazard zonation mapping in parts of Nilgiris, Tamil Nadu, South India
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ORIGINAL PAPER
Relative effect-based landslide hazard zonation mapping in parts of Nilgiris, Tamil Nadu, South India R. Neelakantan & S. Yuvaraj
Received: 9 March 2012 / Accepted: 16 September 2012 # Saudi Society for Geosciences 2012
Abstract The Nilgiri massif, South India, is chronically prone to landslides due to deforestation and the resultant direct entry of rainwater and the final increases of pore pressure leading to landslides in the region. In order to understand such landslide causes, the relative effect method, a new technique, has been adopted for the study area. Among various methods, this is a statistical method developed within the framework of the Geographic Information System to map landslide hazard zones in a mountainous environment. To determine the relative effect (RE) of the factors influencing landslides, data layers of geology, land use/land cover, geomorphology, slope, lineament density, drainage density, and soil were analyzed by calculating the ratio of the unit portion in coverage and landslide, this function that is logarithmic. To quantify the magnitude of factors influencing each grid unit, REs were summed and classified into zones of low-, moderate-, and high-landslide hazard zones. It is also appropriate to follow suitable measures to prevent the landslides in the study area by involving all stockholders and with the active participation of local communities. Keywords Landslide . Hazard zonation . Relative effect method and GIS
R. Neelakantan (*) Department of Industries and Earth Sciences, Tamil University, Thanjavur, Tamil Nadu, India e-mail: [email protected] S. Yuvaraj Research Scholar, Department of Industries and Earth Sciences, Tamil University, Thanjavur, Tamil Nadu, India e-mail: [email protected]
Introduction Among the various natural hazards, landslide is one of the major natural risks in the mountainous areas, which pose a serious threat to human populations and various other infrastructures like highways, rail routes, civil structures like dams, buildings, and other structures, and also lead political unrest, social disharmony, economic stress, and environmental hazards. In the Nilgiri hills of southern India, over 350 landslides have been reported. Landslides occur frequently on cut slopes along roads and railroads (Jaiswal and Van Westen 2009), and occasionally on natural slopes. The scope of this study was to generate a landslide hazard zonation (LHZ) map that can be utilized to identify the potential landslide hazard in the mountainous area. A LHZ map represents a division of the land surface into areas and the ranking of these areas according to degrees of actual or potential hazard from landslides or large mass movements on slopes (Varnes 1984). These hazard maps assist planners in choosing favorable sites for development schemes, such as buildings, dams, and road construction, and this zonation mapping helps to identify the area of potential hazard zones of varying magnitudes. The LHZ is based on different rating number of parameters, adopted by Bureau of
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