15 August 2014
Continuing landslide turmoil in Nepal
Posted by Dave Petley
The Sunkoshi landslide in Nepal – an update
Landslides continue to cause major disruption in Nepal as the summer monsoon intensifies. At Sunkoshi, the major river-blocking landslide continues to confound the attempts by the army to draw down the lake, despite the presence of heavy machinery and now over 50 controlled blasts by the Nepal Army. Indeed, in the heavy rainfall of the last few days reports suggest that the lake level has risen by 50 cm.
I think that there is little doubt that the Nepal Army has been working very hard on this problem, and deploying resources extensively. However, the communications side of the work has gone less well, with repeated statements that the lake level is falling and/or that the problem would be solved within a day or two. This has been proven to be erroneous and overly-optimistic. Unfortunately, the press have taken such statements at face-value, which in turn has generated a huge backlash when the problem could not be resolved. eKantipur today has an article entitled “Shame On You!”, which is strongly critical of the government’s efforts in dealing with all aspects of the landslide. As Nepal moves towards the Desain holiday, which is important for shopping, and imports from the north remain impossible, these pressures are going to rapidly grow.
The bottom line is that there is now a need to both implement a proper communications plan, which should emphasise the need to view this as a long term project (whilst recognising that a rapid breach event can still occur), and to call for expert assistance, in particular from China, where there is considerable expertise in managing these issues. Based on experience elsewhere I suspect that there will be a need to either block the existing channel to blast the base (not an option during the monsoon, and probably not in the dry season either because the dam has so little freeboard across the entire width) or to build a new channel from the foot of the dam upwards. This is a major project that will take some time, assuming that the dam does not breach first. As usual the lack of information about the structure of the dam is a major issue, meaning that its behaviour is unpredictable.
Heavy rainfall across Nepal and N. India causes high levels of loss
Meanwhile, very heavy monsoon rainfall across Nepal and northern India over the last few days has generated high levels of losses from landslides and floods. For example, Republica is reporting 53 people killed and 75 missing in Nepal, although this figure may change considerably as news filters through. Chisapani in West Nepal reportedly received 545 mm of precipitation in 24 hours. At least 23 people have been killed in northern India too. TRMM highlights the areas likely to have been affected by the landslides, which extends along much of the Himalayan Arc: