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In the present study, inner Kumaun Himalayan region between village Jauljibi and Dobaat along the Kali river has been studied to understand the causes and the distribution of landslides in the area. Various geomorphic indices such as longitudinal and topographic swath profile, stream length gradient index, steepness index, and valley floor width to valley height ratio have been extracted for interpreting the active tectonics of the region, and the topographic bedding plane intersection angle (TOBIA) index for the disposition of the bedding or foliation planes of the rocks with respect to the terrain. In addition, the active nature of the thrusts and faults in the region has been interpreted with the offsets or deflection of the river terraces along these thrusts and faults. Interrelationships among these indices and the spatial distribution of landslide indicate that the region between Dharchula and Dobaat is the most tectonically active region as indicated by the presence of Dharchula Fault, Lasku Fault and South Chhiplakot Thrust along with the abnormally high steepness index and knickpoints in the region. Other regions of active tectonics are Dhap—Kalika and Jauljibi—Baniyagaon regions due to Ghatibagarh Kalika Fault, and Berinag Thrust and Rauntis Fault, respectively. In addition it has been reported that the density of landslides in the cataclinal slopes is higher as compared to landslides in the orthoclinal and anaclinal slopes, indicating the role of the disposition of the rocks with respect to the terrain in the spatial distribution of landslides in the study area. [ABSTRACT FROM AUTHOR]

On 04 October 2016, a severe landslide had occurred in the vicinity of Khotila village in Dharchula, region of NE Kumaun Himalaya. This landslide may be classified as typical rockslide, involving thin veneer of debris on the slope as well as the highly shattered rockmass. The slide has been divided into three morpho-dynamic zones, viz., (i) Zone of detachment between elevation 1000 and 960 m, (ii) Zone of transportation between elevation 960 and 910 m, and (iii) Zone of accumulation between elevation 910 and 870 m. The landslide had occurred at the end of the monsoon season when the slope was completely saturated. It has been noted that the area received ∼ 88 % rainfall during the monsoon months which is about two times more rainfall during 2016 monsoon than during 2015 monsoon. Geotechnical testing of the soil overlying the rockmass, corroborate the soil as 'soft soil' with compressive strength of 42 kPa and friction angle of 27.4 ∘ . Granulometry confirms the soil as having > 97 % sand and silt size particles and < 3 % clay size particles, indicating higher permeability. Mineralogically, the soil dominantly constitutes quartz, muscovite and clinochore. Though no swelling clay minerals has been observed, the higher permeability and low strength of the soil, and concentrated higher rainfall during 2016 are the main causes for the landslide to occur. This landslide has partially blocked the flow of Kali river that serve as a boundary between India and Nepal and is endangering the habitants of the Khotila and Bangabagar villages, situated downstream in the Indian and Nepalese side of the Himalaya. In order to understand the stability of the slope, finite element modelling of the landslide has been carried out that points towards higher concentration of stresses in the landslide zone, indicating that there is further probability for the failure of landslide mass. It is therefore suggested that the landslide must be monitored continuously, particularly during the rainy season and also the risk posed by this landslide must be evaluated so as to avoid any further loss to life and infrastructure in the region. [ABSTRACT FROM AUTHOR]