Landslides in relation to terrain parameters - A Remote Sensing and GIS approach
Landslides in Relation to Terrain Parameters
The three terrain parameters drainage, lineament and roads are studied in relation to landslides. For this, drainage density, lineament density and proximity to roads are considered. A cell size of 250m is selected for computation of drainage and lineament density. Landslide and drainage density Drainage density is defined as the ratio of sum of the drainage lengths in the cell and the area of the corresponding cell. A drainage density map (Fig.2) is prepared after computing density for each cell using GIS. The values obtained range from 0 to 15.6 km/km2, which is finally classified into three classes of high, moderate and low drainage density. The spatial data of landslide and drainage density are then integrated in GIS to determine the frequency distribution of landslides for each density classes.  Fig. 3: Lineament density map The landslide frequency which is actually the number of landslides per km2 of density class are given in Table 1.The trend obtained shows that landslide frequency is maximum in low drainage density class. This is not an usual trend in common practice. However, it could be possible that the areas of high drainage density reflecting high surfacial flow do not cause much instability as compared to areas of low drainage density where most of the water infiltrates causing instability. This statement can be supported by the fact that the terrain is dominantly of gneissic rocks and the weathered product of such rocks allows water to easily infiltrate.
Table 2. Landslide frequency in lineament density classes
Table 3. Landslide distribution in road buffers
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