Saturday, October 3, 2009
Tipaimukh Dam, a potential seismic bomb for South Asia
In the light of findings of Sichuan earthquake, seismic vulnerability, tectonic plate formation and the presence of geological faults, the Tipaimukh Dam is technically and financially not viable. In this scenario, pursuing a project blindly would be not only sheer waste of public money but also a potential seismic bomb for the region,
writes Arshad H Abbasi
The earthquake that rocked north-eastern India on September 22, which measured 6.3 on the Richter scale and was of a reasonably long duration, was the fifth in the past 40 days. Located in the foothills of the Himalayas, north-eastern India is bracketed in the highest seismic zone of South Asia, where the three Eurasian, Indian, and Myanmar tectonic plates collide in a subduction mechanism. With this unique tectonic setting and coupled with massive geo-tectonic movements recorded during the past several years, geo-scientists have placed this region in the most fragile zone in the seismic map of the continent. North-eastern India has experienced some of the most devastating earthquakes during the past hundred years. Statistics shows that between 1897 and 1952, there were 44 earthquakes that measured 6.5 or more on the Richter scale. Similarly, between 1953 and 1992, the region had 21 earthquakes of similar intensity. Ignoring the geological and seismic vulnerability and recent warning of the rapid melting of the Himalayas, India is going for a 162.8-metre high dam on the river Barak of north-eastern India, with a storage capacity of 15,900 million cubic metres.
Besides this seismic vulnerability with its hidden dangers of a massive dam break, it has also sparked another serious controversy on water sharing between India and Bangladesh in relation to the Farakka Barrage conflict. India is taking advantages of its regional hegemony and geo-position as upper riparian, causing colossal damage to the Bangladeshi agro-economy by unilateral and disproportionate diversion of the Ganges water by the barrage. The case of the Tipaimukh dam is, however, different from the Farakka Barrage, as it would have a huge storage reservoir.
The geological constraints of the dam site have been reported by Dr Soibam Ibotombi of the Department of Earth Sciences at the University of Manipur, India. According to the report, the tectonic features of the dam site have developed geological faults and fractures that might undergo strike-slip and extensional movements if loaded with the weight of the dam alone. Therefore, these geological faults could be further displaced with accelerated rate by any moderate and large earthquakes and if the dam axis is displaced by a few centimetres a massive disaster leading to huge loss of lives and property in downstream areas could occur.
Putting all seismic and geological constraint aside, no heed is being paid to the protest of local communities and lower riparian Bangladesh and completely ignoring the UN convention on international watercourses. The enormous weight, about 15.9 billion tonnes of water, would bear on the substrata of the dam site could not have been taken into consideration, as scientists today have identified more than 100 cases of earthquakes triggered by reservoirs.
The most serious precedence of dam or reservoir-induced seismicity is the 7.9-magnitude Sichuan earthquake in May 2008, linked to the construction of the Zipingpu Dam. The case of Sichuan earthquake was presented at the American Geophysical Union and, findings also published in the Chinese Geology and Seismology Journal. The devastating earthquake killed 68,000 people and left about 11 million people homeless. China is spending $146.5 billion to rebuild areas ravaged by the earthquake. In a recent study, it was found that the Zipingpu Dam project was the cause of this devastation. Earthquakes were very unusual for the area as no previous seismic activities were ever recorded.
The Indian authorities ought to remember that triggered by an earthquake of 6.3 magnitude caused because of the filling of a dam flattened the village of Koynanagar in Maharashtra, western India, on December 11, 1967, killing around 180 people, injuring 1,500 and rendering thousands homeless. The dam was seriously damaged and power cut off to Bombay, causing panic among its populace, who felt the quake 230 kilometres from its epicentre. The epicentre of the tremor and numerous fore and aftershocks were all either near the Koyna Dam or under its reservoir.
At a seminar on ‘water dispute in South Asia’, held in Dhaka on August 18-19, in which the water resources secretary of the Bangladesh government disclosed that the Tipaimukh dam was conceived in 1955 but the then erstwhile Pakistani government never agreed to its construction. But, immediately after the independence of Bangladesh, the Indian prime minister rushed to Dhaka to set the Indo-Bangladesh Joint Rivers Commission and in the very first meeting of the commission, India informed Bangladesh of the Tipaimukh project. And, since the same meeting Bangladesh continuously has been asking India for data on the Tipaimukh Dam project. However, the Indian authorities did not share any study report or design on the dam. This attitude of India shows that there is no technical or scientific study detail behind the theoretically redundant project to share with all stakeholders except agenda to impose its hegemony over South Asia.
The height of the Zipingpu dam is 150 metres and total weight of filled water was 1.12 billion tonnes, thirteen times less than the proposed capacity of the Tipaimukh Dam. Above all, its sub-geological features were more stable than those of the Tipaimukh dam site. In the light of findings of Sichuan earthquake, seismic vulnerability, tectonic plate formation and the presence of geological faults, the Tipaimukh Dam is technically and financially not viable. In this scenario, pursuing a project blindly would be not only sheer waste of public money but also a potential seismic bomb for the region. The objective of a dam which is to control floods and provide hydroelectric power generation could also be achieved by adopting alternative methods.
There is no doubt that frequency and intensity of floods are on the rise in the region but its root cause is massive deforestation, compounded with rapid population growth and uncontrolled development in Brahmaputra Basin. Because of increased warming of the Himalayas, the solution to floods in the Basin lie in integrated watershed management. This would necessitate immediate afforestation to increase vegetative cover and coupled with rainwater harvesting techniques it could achieve the same objective with less investment and above all without disturbing the ecology of a fragile and fractured region. Similarly, hydro electric power could be generated by run-of-river option requiring minimal water pondage. Indian authorities need to shelve Tipaimukh dam project immediately to avert the lurking danger of a massive earthquake in the region.
Arshad H Abbasi is a visiting research fellow at the SDPI-Islamabad and conducted research on earthquake 2005 with collaboration of the University of Zurich Switzerland-Southern. email@example.com