Bhasha dam’s site is not a natural site for a storage dam, like Tarbela and Kalabagh. It was identified as a site for hydropower development by the World Bank in 1967. However, its first feasibility report was drawn for a storage dam on cue by Wapda in 1984. The RCC Bhasha dam height is 922 feet with a water storage capacity of 6.7 maf and hydropower generation of 4500 mw. There is no other dam of this height in the world.
Being a former UN and World Bank Chief Technical Advisor, I have observed some reservation and I think they need to be addressed first. The safety aspects of 922-feet high RCC Bhasha dam stemmed from its unprecedented height and field risk factors. There is no RCC dam anywhere higher than 620 feet in China. RCC is relatively soft and vulnerable to cracks and leakage compared to conventional vibrated concrete used for building thousands of high dams, bridges and skyscrapers etc.
The location of Bhasha dam falls under an active earthquake zone and in the valley terrain prone to extraordinary environmental hazards. This region is seismically very active due to its position near the collisional boundary of the Indian and Asiatic tectonic plates.
The proposed dam site is located in the Kohistan region. The Kohistan terrain represents an intra oceanic “Island Arc” which was formed as the result of the collision process of the Indian and Eurasian plates. Grave seismic risk was demonstrated by magnitude 7.6 earthquake of October 8, 2005. Incidentally, it had also been predicted by a German consultant of a hydropower project that Bhasha site falling in a seismically very sensitive zone, an earthquake of magnitude 7.5 could occur any time here. He proved right as noted above. The earthquake devastated the region causing a great loss of life and property, particularly in Azad Kashmir.
Another serious risk factor may be reservoir induced seismicity primarily due to immense weight of water stored behind a dam. It can trigger tremours. India’s Koyna dam induced magnitude 6.4 earthquake killing 180 people in 1967. A far more disastrous was the recent exceptionally 7.9 magnitude earthquake believed to be induced by water weighing 320 million tons stored behind 511 feet high Zipingpu dam built in 2004 on the Minjiang (Min) tributary of China’s Yangtze River. Reportedly 80,000 people were killed. (Wall Street Journal Feb 6, 2009).
In 2005, the government retained Diamer-Bhasha dam Consultants (DBDC) with a German company as the lead firm. This company was not qualified to be retained as it was blacklisted by the World Bank for having been found involved in cases of corruption and payoffs. This firm was also Consultant for India’s controversial Baglihar project.
Construction of Bhasha roll-crete dam with unprecedented height of 922/892 feet in a very active seismic zone and a valley bedevilled by hazards like avalanches, massive landslides and lake bursts, would be like sailing in unchartered waters.
Both Zipingpu and Vajont disasters occurred on tributary rivers. Their Impact largely dissipated by the time each joined respective parent river. However, in the event of failure or overtopping of Bhasha dam built on the main Indus – world’s fifth largest river, could be a recipe for a disaster of catastrophic proportions.
I appeal to the Chief Justice of Supreme Court of Pakistan to take suo motu notice of this issue in the public interest and prevent construction of 922/892 feet high RCC Diamer-Basha dam to protect life and limb of 180 million people of Pakistan and their country from catastrophic risks all the way 1200 miles down the valley to the sea coast.
ENGR BASHIR A MALIK