AROUND THE REGION
China, India must both review Himalayan region dams
The commissioning of the $ 1.5 billion Zangmu hydel project on the Yarlung Tsangpo ( Brahmaputra in Tibet) has again triggered downstream concerns in India. Though China keeps insisting it will do nothing against Indian interests and promises that all these hydel projects on the Yarlung Tsangpo , there is surely some cause for worry. Nimmi Kurian of the Center for Policy Research (CPR) has rightly flagged the key issue that the "cumulative impact of run-of-the-river dams also remains ill-defined and little understood."
The Ninth Report of the Inter-Ministerial Expert Group on the Brahmaputra (IMEG) in 2013 called for a close monitoring of the 39 run-of-the-river projects on the Yarlung Tsangpo and its tributaries. But the big question is whether there has been any progress on that . Nimmi is right when she says that despite being projected as run-of-the-river projects, one cannot remain oblivious to the fact that the Jiexu, Jiacha and Zangmu dams are within 25 km of each other and at a distance of 550 km from the Indian border .
The other factor that should worry both India and China -- and other countries in the region -- is the increasing frequency of earthquakes in the Himalayan region. The recent earthquakes in Nepal and Afghanistan , when tremors were felt across the northern sweep of South Asia and China's Tibet region , should drive home the criticality of a fresh review of all hydel projects in the Himalayan region by India and China and also the smaller Himalayan countries like Nepal and Bhutan whose economy depend so much on power exports.
This has become necessary after the recent Nepal- Afghanistan earthquakes -- and the ones that preceded them, like the 8 Oct 2005 Kashmir earthquake, that killed more than 80,000 people on either side of the border.
Though not much research has been reported in India on the correlation between dam building and earthquakes, there is a very interesting Chinese study on a 2008 earthquake in Sichuan that was as devastating as the 2005 Kashmir earthquake.
Chinese geologist Fan Xiao , a chief engineer with the Regional Geological Survey team , who conducted the study for four years between 2008 and 2012 , found a direct correlation between the construction and commissioning of the of the 760 MW Zipingpu embankment dam on the Min river in Sichuan province and the deadly Sichuan earthquake on 8 oct , 2008. The earthquake not only killed more than 80,000 people but caused damage to hundreds of dams in Sichuan province.
Chinese media initially reported that 391 dams had been damaged by the Oct 8 earthquake and major cracks were reported in the largest of them -- the Zipingpu dam. Later the Chinese water resources ministry said as many as 2360 dams had been effected by the earthquake. Fan Xiao attributed the 8 Oct earthquake to a phenomenon called Reservoir Induced Seismicity -- that US experts had earlier warned about in areas where huge dams are commissioned at some speed .
An Indian expert V P Jauhari had raised similar concerns in a paper prepared for the World Commission on Dams . V. P Jauhari wrote the following about this RIS phenomenon, known as Reservoir-Induced Seismicity (RIS): "The most widely accepted explanation of how dams cause earthquakes is related to the extra water pressure created in the micro-cracks and fissures in the ground under and near a reservoir. When the pressure of the water in the rocks increases, it acts to lubricate faults which are already under tectonic strain, but are prevented from slipping by the friction of the rock surfaces."
Jauhari said that since every dam has unique geological characteristics, it is not possible to accurately predict when and where earthquakes will occur. However, after submissions by experts like Jauhari , the International Commission on Large Dams has strongly asserted that the 'RIS factor' should be taken seriously for reservoirs deeper than 100 meters.
Another top Indian expert, Harsh K Gupta, summarized the impact of the RIS phenomenon in 2002.
He said the reservoir is the most important factor, but the volume of water also plays a significant role in triggering earthquakes.
· RIS can be immediately noticed during filling periods of reservoirs.
· RIS can happen immediately after the filling of a reservoir or after a certain time lag.
Many dams have been built in seismically active regions, including the Himalayas, Southwest China, Iran, Turkey, and Chile. But global environment groups have already appealed for a moratorium on the construction of high dams in earthquake-prone areas. It is time India and China, and other countries in the Himalayan region, take RIS-related concerns seriously and factor that into their plans for building dams. It is not just important to do examine whether a dam is built to withstand earthquakes – it is important to examine whether too many dams — and big ones – will make earthquake a recurring feature in the region.
(Subir Bhaumik is a former BBC Correspondent and now works as Senior Editor of Dhaka-based bdnews24.com. His books on Northeast " Insurgent Crossfire" and " Troubled Periphery" are well acclaimed. His forthcoming book " Agartala Doctrine" is being published by Oxford University Press.)