Inferring potential landslide damming using slope stability, geomorphic constraints, and run-out analysis: a case study from the NW Himalaya

Vipin Kumar,Rajinder K Bhasin,Imlirenla Jamir,Vikram Gupta

doi:10.5194/esurf-9-351-2021

Abstract

Abstract. Prediction of potential landslide damming has been a difficult process owing to the uncertainties related to landslide volume, resultant dam volume, entrainment, valley configuration, river discharge, material composition, friction, and turbulence associated with material. In this study, instability patterns of landslides, geomorphic indices, post-failure run-out predictions, and spatio-temporal patterns of rainfall and earthquakes are explored to predict the potential landslide damming sites. The Satluj valley, NW Himalaya, is chosen as a case study area. The study area has witnessed landslide damming in the past and incurred losses of USD ∼30 million and 350 lives in the last 4 decades due to such processes. A total of 44 active landslides that cover a total ∼4.81±0.05×106 m2 area and ∼34.1±9.2×106 m3 volume are evaluated to identify those landslides that may result in potential landslide damming. Out of these 44, a total of 5 landslides covering a total volume of ∼26.3±6.7×106 m3 are noted to form the potential landslide dams. Spatio-temporal variations in the pattern of rainfall in recent years enhanced the possibility of landslide triggering and hence of potential damming. These five landslides also revealed 24.8±2.7 to 39.8±4.0 m high debris flows in the run-out predictions.

Highlights

Landslide damming is a normal geomorphic process in narrow river valleys and poses significant natural hazard (Dai et al, 2005; Gupta and Sah, 2008; Delaney and Evans, 2015; Fan et al, 2020)
This study provides detailed insight into the regional instability pattern, associated uncertainty, and potential landslide damming sites, and it can be replicated in other hilly terrain that witnesses frequent landslides and damming
High total displacement (TD) is obtained by the rockfall and rock avalanche of the Lesser Himalaya Crystalline region (Fig. 4)

Summary

Introduction

Landslide damming is a normal geomorphic process in narrow river valleys and poses significant natural hazard (Dai et al, 2005; Gupta and Sah, 2008; Delaney and Evans, 2015; Fan et al, 2020). Studies concerning the prediction of potential landslide dams and their stability at a regional scale have been relatively rare, in the Himalaya despite a history of landslide damming and flash floods (Gupta and Sah, 2008; Ruiz-Villanueva et al, 2016; Kumar et al, 2019a). (i) pre- and post-failure behaviour of landslide slopes and the (ii) landslide volume, stream power, and morphological setting of the valley (Kumar et al, 2019a). The selection of input parameters in FEM analysis and the set of assumptions used (material model, failure criteria, and convergence) may result in uncertainty in the final output (Wong, 1984; Cho, 2007; Li et al, 2016). Post-failure behaviour of landslides can be understood using run-out analysis

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Conclusion