Evaluation of potential landslide damming: Case study of Urni landslide, Kinnaur, Satluj valley, India

This work aims to understand the process of potential landslide damming using slope failure mechanism, dam dimension and dam stability evaluation. The Urni landslide, situated on the right bank of the Satluj River, Himachal Pradesh (India) is taken as the case study. The Urni landslide has evolved into a complex landslide in the last two decade (2000-2016) and has dammed the Satluj River partially since year 2013, damaging similar to 200 m stretch of the National Highway (NH-05). The crown of the landslide exists at an altitude of similar to 2180-2190 m above msl, close to the Urni village that has a human population of about 500. The high resolution imagery shows similar to 50 m long landslide scarp and similar to 100 m long transverse cracks in the detached mass that implies potential for further slope failure movement. Further analysis shows that the landslide has attained an areal increase of 103,900 +/- 1142 m(2) during year 2004-2016. About 86% of this areal increase occurred since year 2013. Abrupt increase in the annual mean rainfall is also observed since the year 2013. The extreme rainfall in the June, 2013; 11 June (similar to 100 mm) and 16 June (similar to 115 mm), are considered to be responsible for the slope failure in the Urni landslide that has partially dammed the river. The finite element modelling (FEM) based slope stability analysis revealed the shear strain in the order of 0.0-0.16 with 0.0-0.6 m total displacement in the detachment zone. Further, kinematic analysis indicated planar and wedge failure condition in the jointed rockmass. The debris flow runout simulation of the detached mass in the landslide showed a velocity of similar to 25 m/s with a flow height of similar to 15 m while it (debris flow) reaches the valley floor. Finally, it is also estimated that further slope failure may detach as much as 0.80 +/- 0.32 million m(3) mass that will completely dam the river to a height of 76 +/- 30 m above the river bed. (C) 2018, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V.