Sunkoshi landslide in Nepal and its possible impact in India: A remote sensing based appraisal
Other literature type
Champati ray, P. K.
Chattoraj, S. L.
(issn: 2194-9034, eissn: 2194-9034)
A devastating landslide that killed at least 156 people occurred on the right bank of Sunkoshi river at village Jure, 70 km northeast of
Kathmandu in Nepal. It not only affected hydroelectric projects in the near vicinity but also had potential to flood large tracts of
downstream area in Nepal and north Bihar. Timely action by Nepal Army and Indian authorities have averted a major disaster but
satellite data analysis (using IRS Resourcesat-2 LISS IV, WorldView-2, RISAT-1, Radarsat-2 etc.) reveal that the site was easily
identifiable on satellite image as a potential landslide zone that has been affected by landslide related mass wasting in the past. It was
reactivated and intermittently slided during 2000–2012 and finally when the whole mass came down on 2nd August 2014 pushing
materials up to the opposite slope, a landslide dammed lake was formed on Sunkoshi river which extended up to a distance of 2.5–3 km
as observed on 5–6th August on satellite images and the volume was estimated to be around 8.26–10.5 MCM, which needs to be released
safely to avert any further disaster. Attempt is made to simulate the event to assess the run out and debris thickness using process based
model. Satellite observation (using IRS Resourcesat-2 LISS IV, WorldView-2, RISAT-1, Radarsat-2 etc.), aided by hydrological data
obtained through telemetry immensely helped to assess the landslide dimension, lake extent, volume, discharge, water level and travel
time of water in Sunkoshi river. But the question remains how to manage the large amount of debris that Sunkoshi brings to its
downstream areas causing river aggradations that eventually increases the flood risk. In such situations, the most immediate landslide
remedial measures are four fold: monitoring of landslide, dam and reservoir using remote sensing and hydrological observations,
controlled release of water, water discharge management at Kosi barrage and mechanism/preparedness for evacuation. The Sunkoshi
landslide has brought to forefront the core issue of analysing mass wasting in all major river valleys outside Indian territory that can
pose risk to Indian population. In this regard, it is needless to say that remotely sensed images through Indian Remote Sensing satellites
and many other satellites can provide most crucial information in short time.