Landform and slope instability in Himachal Himalaya - A case study of Baner Khad watershed, Himachal Pradesh, India

Evaluation of landform, slope and anthropogenic activities has been done in the Baner Khad watershed, Himachal Himalaya (32 degrees 04' to 32 degrees 18'N and 76 degrees 13' to 76,32, E with an area of 395 sq km) for studying active landslides. Landform characters have been studied by dividing the area into six geomorphic zones based on elevation, slope, vegetation and microclimate, keeping in view topography of the area. Evidences of break in slopes are shown by longitudinal profiles of the streams. Slope analysis involves quantitative classification of slope with slope angles derived from topographic maps and the area has been divided into five slope categories. Important landslide sites have been identified during field investigation. These were studied in the context of geological aspects such as lithology, proximity to active thrusts, geomorphological aspects such as landform, slope, erosion by streams and anthropogcnic activities. It has been observed that the landslides at Chohla village, Kand village and near Manjhi Khad are caused by natural factors where the fragile lithology plays the main role along with toe cutting on very gentle to gentle slope. Slides near Thatri village and in Dhar Narwana are structurally controlled where the Chail Thrust and the Main Boundary Thrust pass through moderately steep slopes. Landslides at Gamru, Jogiwara, and near Kand Tea Garden (falling in very gentle to gentle slope category) are caused by the unplanned construction in the geological fragile area whereas the slides at Bhagsunath and Kahmara areas are due to the unsystematic mining of slates on the moderately steep slopes. Remedial measures, keeping in view the conditions at different landslide sites, have been suggested.