VULNERABILITY MAPPING OF LANDSLIDE VIA GIS

VULNERABILITY MAPPING OF LANDSLIDE VIA GIS

TAMIM HAMSAR1, AMIT TALGOTRA2

1M. Tech Scholar

2Assistant Professor,

1Civil Engineering,

Sri Sai College of Engineering and Technology Badhani, Pathankot

ABSTRACT:- In the present study detailed work has been carried out in and around Udhampur, Jammu and kashmir, India with the main objective of demarcating landslide vulnerable zones using remote sensing and Geographic Information System (GIS) techniques. Udhampur town lies between 32°34’ & 39° 30’ North latitudes and 74°16’ & 75°38’ East longitudes and is covered by parts of Survey of India degree-sheet numbers 43O, 43K, 43P and 43L. The district has a total geographical area of 4540 sq km. The main triggering factors of landslides in the study region are rainfall, slope, soil, land use and manmade activities. The average annual rainfall of this region is about 1300mm. The entire study area is occupied by charnockites with smaller intrusions of dolerite dykes. Two third of the study is covered with sandy loam soil and the remaining by clay loam soil. The most parts of the study area are falling under the categories of gentle and moderate slope (2º to 15º). Land use / land cover maps for the years 2019 and 2020 were prepared from Landsat TM and IRS Resourcesat-2 satellite imageries respectively. Supervised classification technique was used to prepare land use / land cover maps from the satellite data. The land use / land cover maps of 2019 and 2020 were compared and integrated using GIS to carry out the change detection analysis. The change detection matrix was also prepared using GIS to understand the changes occurred in each land use/ land cover category. The analysis indicates that there is a huge transformation of forest land into agricultural land from 2019 to 2020. Minor changes have occurred in the other land use / land cover categories also. Soil samples and core samples were also collected in the field during field visits, and the samples were tested in the laboratory for various engineering properties. Compaction and direct shear tests were carried out to assess the strength characteristics of soils. Sieve and hydrometer analyses were done to know the percentage of sand, silt and clay in soil samples. Liquid limit, plastic limit and plasticity index were also calculated for the samples. XRF and XRD studies were done to know the composition and mineralogy of the soil samples. As number of landslides occurred around Udhampur were studied for preparing landslide vulnerability zonation map. The past landslide details were also collected and the landslide scar map of the study area was prepared using GIS. To prepare landslide vulnerability zonation map, various themes such as geology, soil, rainfall, drainage, groundwater level, geomorphology, land use and slope were considered. For the above mentioned nine themes, the thematic maps were prepared from satellite imageries using GIS with the support of Survey of India toposheets. Weightages were assigned to the above nine themes, and also ranks were assigned to the sub-parameters in each theme. Finally the landslide vulnerability zonation maps for Udhampur were prepared separately by integrating all the thematic layers using GIS. The landslide vulnerability map of Udhampur shows that the north-eastern and south-western parts of the vulnerable to landslides than the other parts. This is also crosschecked using the previous landslide records. The landslide scar map which was finally placed over the vulnerability zonation map exhibits perfect matching. This shows the accuracy of the weights and ranks assigned to various themes.