Characteristics of Large Landslides and Application of Frequency Ratio Model for Susceptibility Assessment, Lower Jalal Catchment (Himachal Pradesh)

Abstract

Landslide susceptibility study is dealt to analyze the spatial probability of the phenomenon. This paper focused on the frequency ratio methods for producing landslide susceptibility map. A detailed landslide inventory with 36 landslide locations was prepared using the satellite imagery and field survey of the study area. Out of these 36 landslide locations, 12 of the sites surveyed and 24 landslides were identified using satellite imagery. DEM of the area prepared to analyze relief, aspect, and slope. Contour lines were digitized from the topographical map for the topographic analysis, geological map, land use, road network prepared into a geospatial data using the ArcGIS software. The predictive variables that influence slope instability such as slope angle, aspect, plan curvature, lithology, distance to faults, soil type, landuse, distance to road, distance to stream and dissection index were used for the landslide susceptibility modeling of the study area. The weightages of these variables were determined by the landslide frequency ratio (LFR) method, and sum of these variables is calculated as landslide susceptibility indices (LSI), which shows the severity of the phenomenon. The landslide susceptibility analysis was validated using the 20 landslide locations dataset. The validation results revealed that landslide susceptibility map has 87% accuracy for predicting the landslides in the study area.