V1: Landslide Inventory - Anthropogenic Activities and the Two-Fold Surge in Landslides During the 2023 July-August Extreme Rainfall in the Lesser Himalayas

Less Himalaya, part of Himachal Pradesh, has witnessed unprecedented precipitation in the second week of July 2023, resulting in flash floods and landslides that eventually led to widespread destruction and economic loss. The monsoon activity was vigorous on July 7-11, 2023 in isolated pockets of the region. District Solan and Shimla received 472 mm and 268 mm of rainfall against its normal rainfall of 52 and 35 mm in 5 days with a deviation of over 800% and 600% respectively, which is unprecedented as per records.

A total of 3535 landslides were mapped from the study region triggered after the heavy rainfall in July and August 2023. Among these, 3176 landslide polygons, equalling 2.83 km2 area, were delineated from the post-event satellite images. Whereas, a greater number of small shallow landslides occurred along the road cliffs, which were not clearly visible in the satellite images. We identified them during our multiple field visits, and demarcated about 359 landslide points from the road sections.