|
|
|
Landslide zonation for hill area development
Dr.S.S. Ramakrishnan
Sr. Lecturer
V.Sanjeevi Kumar
Sr. Project Associate
M.G.S.M. Zaffar Sadiq
Research Scholar
Dr. K.Venugopal
Director
Institute of Remote Sensing, Anna University,
Chennai- 600 025,Tamil Nadu, INDIA.
Ph : 91-44-2352189,Fax:91-44-2352166
Email : zaffar_s17@hotmail.com
Sanjeevee_varadhan@hotmail.com
Introduction
Landslides are frequent and annually recurring phenomenon in the Nilgiri district. Outward and downward movement of mass, consisting or rock and soils, due to natural or man-made causes is termed as landslide. High intensity rainfall triggered most of the landslides in the Nilgiri district. As long as landslides occur in remote, unpopulated regions, they are treated as just another denudation process sculpting the landscape, but when occur in populated regions, they become subjects of serious study. Most of the landslides occur due to exhaustive deforestation for the development of urbanization and plantation. In these areas rainwater directly penetrates into the soil and cause landslides.
- Classification of Landslides
Based on the mass movement, landslides are divided into four major groups.
- Slow Flowage: Rock Creep and Soil Creep
- Rapid Flowage: Earth movements, Mudflows, Debris Avalanche
- Sliding: Slumps, Rock Slides, Rock falls, and Landslips
- Subsidence: Sinking of mass
- Causes of Landslides
- Internal factors
The steeping of the slope, water content of the stratum and mineralogical composition and structural features, which are tending to reduce the shearing strength of the rocks.
- External factors
A slight vibration or jerk to the mass would greatly add up against the frictional resistance and the mass would become unstable. The heavy traffic on hill roads is of great contributing factors towards causing the imbalance of the masses.
Objectives
- To create spatial database in GIS environment.
- To delineate the comprehensive landslide prone areas in various zonation level.
- To visualize landslide prone areas in 3D view for hill area planning.
Study area
Study area is located in Nilgiri district, which is a mountainous terrain in the North West part of the TamilNadu, and the study area covers a part of the Kothagiri Taluk. It is geographically located between 76° 14' 00" and 77° 02' 00" E longitude and 11° 10' 00" and 11° 42' 00" N latitude. The study area falls under the Survey Of India toposheet No: 58A/15 on scale 1:50,000 scale.
Methodology
- Landslide Hazard Zonation Mapping
Orthophotos were prepared form the aerial photos and then the contour maps with 2m interval are generated from the orthophotos. The digitized contour maps are given as input into the GIS - ArcView 3D analyst. Here, the 3d visualization of the study area is created. Various thematic layers (slope, landuse, soil) are visually interpreted from the orthophotos. The delineated thematic layers were digitized. The landslide model is created and the ranks and weights are assigned to each category. Based on themes and its impacts different zones were delineated.
|
|
|