Soil erosion risk assessment and its impact on landslides – A study on parts of Himalayan Region, India

The research carried out reveals the annual soil erosion risk assessment and its relation in landslide vulnerability in the Shimla tehsil, Himachal Pradesh, India. The study area has a geographical area of 368 km2. Datasets such as Survey of India topographical maps, Soil maps from Soil and Landuse Survey of India (SLUSI), rainfall datasets from Shimla meteorological centre and LANDSAT 8 imageries have been used to retrieve the annual soil loss. Landslide inventories have been collected from 2000 to 2020 through LANDSAT 8 OLI, Sentinel 2A and Google Earth satellite imageries. The datasets have been processed in the GIS environment and the final results have been cross-correlated with the landslide inventories to evaluate the relationship between soil erosion and landslide vulnerability. The rate of soil erosion was differentiated into five classes ranging from 0.03 to 2.1, where 0.03 represents the least amount of soil erosion and 2.1 represents the highest amount of soil erosion. The values less than 0.1 were observed all through the places covering forest and slope areas which is least prone to soil erosion. The values between 0.12 to 0.5 indicate medium to high stage soil erosion. These areas cover agricultural fields, degraded forests and forest blanks. The areas with the highest amount of erosion were observed along with the Barren lands and Built-up lands where the rate of erosion exceeds more than 30. A total of 96 landslides were mapped from the Google earth imageries for the year 2017. Among these landslides, nearly 79.1% occur along the Very low rate of soil erosion and 20.8% occurred along the low rate of soil erosion. The landslides are clustered in the study area mainly located along populated areas such as Shimla Town, Mashbora, Dhalli etc. Some of the landslides are located along the National highway extending between Rampur to Shimla.