Nearly a month after the April 25 earthquake, the aftershocks, which have otherwise become no more than statistics – five today and three yesterday, with the epicenter north of Kathmandu or faraway in Dolkha – continue to be of some concern. The USGS advisory issued on May 20 haven’t ruled out possibility of stronger aftershocks, though their probability is decreasing. People, whose houses are unaffected, have moved from makeshift tents to the ground floor, unsure about the safety on the first or second floor.
Now, the focus is gradually shifting to what will happen when monsoon begins. What worries the scientists, the authorities and the people in general are the looming threats of landslides and slope failures in the EQ affected hills. Experts from around the world are focusing their attention on gaining understanding of the changes caused to the landform by the earthquake and the likely threats they might pose when the monsoon rain begins. An Ariel reconnaissance conducted by a group of geo-scientists and disaster experts from various organizations reported that two earthquakes within a fortnight triggered at least 3,000 landslides causing large landmass movement in the EQ affected area. Another study, conducted using satellite imagery, concluded that many more landslides may occur in the monsoon, because the zone of intense landsliding corresponds to areas with high rates of seasonal rainfall-triggered landslides. The study also warns that the rainwater will wash landslide sediment downstream onto valley floors and floodplains causing damages to areas downstream.
Landslide hazards aren’t uncommon in the hills of Nepal inhabited by almost half of the country’s 27 million people. It is a problem we face every year. In fact, roughly 12,000 landslides/slope failures occur in Nepal every year. Though some studies were conducted in the 1960s and 1970s to highlight how landslides damage lives and properties, the problem could not draw the ‘attention’ it deserved in the development programs because landslides were one among many problems facing mostly rural population. Interest in landslide mitigation and stabilization rapidly began to grow with increase in development of infrastructures such as roads, reservoirs, irrigation canals, drinking water intake sites, and power plants, which were somehow connected with the well-being of the inhabitants of the capital and other urban centers. Any damage to these infrastructures would mean a concern for the urban economy as well. Most of the studies carried out on landslides have been focused on road corridors, while there, are many landslides that have caused problems to properties in road-less areas too. The concern of saving the villages from sliding is equally, if not more, important than saving vital infrastructures. Do we have the capacity to deal with the size and nature of the problem?
Let’s do some back-of-the-envelope (referred to later in this article as “BOTE”) calculation to see our capacity to deal with landslide problems. At least five agencies working under four ministries with different expertise, skills and priorities are involved in works related to landslide stabilizations.
- DSCWM (the Department of Soil Conservation and Watershed Management) of the Ministry of Forests is mandated to work on watershed protection. With its management programs in critical watersheds of 61 districts in the country, the department appears to have been stabilizing roughly 200 small to medium landslides a year.
- DoR (the Department of Roads) of the Ministry of Physical Infrastructure and Transport stabilizes only those landslides that pose threats to the roads or to vehicular movements. The DoR may be stabilizing about 200 small to large landslides along the road in the hills every year.
- DoI (the Department of Irrigation) under the ministry of irrigation also works on landslide stabilization, but only when they pose threats to the irrigation canals. It can be safely said that the DoI also works on roughly 100 small to medium landslides along the irrigation canals a year.
- DWIDP (the Department of Water Induced Disaster Prevention) of the Ministry of Irrigation is mandated to deal with floods and landslides, but it is more involved in flood control works. Again let’s say DWIDP has the strength to stabilize another 100 medium to large landslides a year.
- DDCs (the District Development Committees), a strong local body authorized by Local Governance Act to plan its own development program, provide financial support to VDCs for climate change, resource conservation and environment related works, which often include landslide stabilization works too. We can say that a DDC supports roughly another (in addition to what other departments have done in the district) 20 landslide stabilization works a year.
The BOTE calculation shows that if we pull together the total strength of the departments (1-4 above), we can treat about 600 landslides a year. Adding DDCs strength, we might be able to pull another 600 ( in 29 EQ affected districts). With this estimate based on a very rough but higher side figures, it appears that we are hardly near halfway to deal with the problem of 3000 landslides, which do not include the landslides that might get triggered with monsoon. In addition, by the time we stabilize 1200 landslides, there will be new ones initiated by the monsoon. And there will be other districts as well where new landslides may require immediate attention.
Although sophisticated methods have also been used successfully in landslide stabilization works in Nepal, the conventional methods used in landslide stabilization involve use of retaining walls to hold the sliding mass supplemented by application of bioengineering measures to reduce surface erosion. Landslide stabilization work, essentially, is expensive, and hence out of reach of poor farmers. Since retaining walls seem to do a quick fix, it has discouraged developing less expensive methods.
Although many landslides may get stabilized by themselves over a period of time, those that pose threat to lives and properties need our immediate attention. However, judging from the point of view of physical capacity and the financial strength that we have, stabilizing this overwhelming number of landslides across the EQ affected region or at least minimizing the likely damages, could simply be a nightmare, if not planned in a manner that is quick enough to implement and simple enough to allow involvement of all sorts of ways of treating landslides that have been proved successful elsewhere.
With support from Irene Upadhya