Landslide Occurrences under Diverse Landuse/cover in Lower Kosi Watershed, Central Himalaya

Abstract

Present study was related to land degradation after landslide and risk analysis of Lower Kosi watershed in Central Himalaya using RS and GIS. The study was aimed to identifying the relation of land use with landslide activity in Himalayan terrain and landslide management. The landslide inventory map was prepared for the detailed study with the help of Google Earth Image and field verifications. Landslide had been sub-categorized into two categories; natural and road induced. The land use map was prepared from Google Earth image followed by toposheets. Statistical analysis of landslide frequency and density as well as frequency and density ratios were applied. The collected data was evaluated in combination with GIS. The relationship between land use categories and landslide occurrences was determined. The landslide frequency ratio (FR) and density ratio (DR) were analyzed. The FR and DR value of 1 is an average value. Hence, the value of ratio more than 1 signifies a strong relationship between landslides and the given factor while ratio values less than 1 registers a poor relationship. The FR and DR values were >1.0 in the areas of fallow land, barren/rocky land, agricultural land and open forest revealing a strong relation to landslide processes while the lesser values of FR and DR in ‘dense forest’ area determines the impact of sufficient vegetation cover on the least occurrence of landslides. This study may be applicable for new and existing land use planning projects as the adopted methodology provides rapid estimation of landslide vulnerability of the area.