Recurring Landslides and Debris Flows near Kalli Village in the Lesser Himalayas of Western Nepal

Landslides and debris flows frequently occur in the mountainous areas of the lesser Himalayas of Western Nepal, posing a significant threat to infrastructure and residents across this region. The present study is focused on the potential causes and influence factors of these recurring geohazards that initiated in Kalli village of Achham district. A field investigation was carried out to study the characteristics and triggering factors of the landslide and subsequent debris flows. It is found that the debris flow in the area typically evolves in multiple stages based on intensity and volume of the rainfall. The deposition pattern shows that the larger debris particles have a tendency to travel longer and the flows can be extremely destructive and carry high momentum in this area. The laboratory testing results suggest that the differential weathering of underlying inter-bedded shale and sandstone of Suntar Formation could be a major cause of the recurring landslides; other factors including the topographic wetness index, slope, drainage pattern, seepage and land-use practices around the study area could contribute and the rainfall could act as a major triggering agent to both landslides and debris flows.