‘Diamer dam site prone to seismic hazards’: WB Chief Technical Advisor
Islamabad – Former UN and World Bank Chief Technical Adviser Eng Bashir A Malik has expressed reservations about the recently started Diamer Bhasha dam.
In an appeal to the chief justice of Pakistan, he said that Bhasha was 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,” he said.
“Diamir Bhasha appeared to be but a political or fake dam! Trickery did pay on 17 January 2006, when Musharraf suddenly announced building it first instead of KBD. The safety aspects of the 922-foot 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,” he added. “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 a 7.6 magnitude earthquake of October 8, 2005,” he elaborated.
Incidentally, he said, it had also been predicted by a German consultant of a hydropower project that the Bhasha site falling in a seismically very sensitive zone, an earthquake of magnitude 7.5 could occur anytime. “He proved right as noted above. The earthquake devastated the region causing 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 a 6.4 magnitude earthquake killing 180 people in 1967. A far more disastrous was the recent exceptionally 7.9 magnitude earthquake believed 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. It must be noted that the weight of water would be far lower than the 922 feet high Bhasha Dam – almost twice the height of Zipingpu. Risk could be greater due to its location in a very active seismic zone.”
He said, “Surprisingly, Bhasha project report did not address risk of reservoir induced seismicity. “The Indus valley host to Bhasha Dam was known for massive avalanches, landslides, rock/snow dams and lake bursts. In the mid-19th century, part of a mountain near Nanga Parbhat fell into the Indus triggered by an earthquake.
IN PAKISTAN ALMOST ALL DAMS ARE AT THE SAME SEISMIC RISK, EG. MANGLA DAM, WARSAK DAM AND TERBELA DAM ARE ALL NEAR TO MAJOR SUTURE AND COLLISION ZONE, SOME OF THEM ARE VERY NEAR TO MAJOR ACTIVE FAULTS AND SOME ARE JUST ABOVE THE OFFSHOOTS OF THOSE MAJOR FAULTS. BUT EVEN THEN THESE DAMS WERE CONSTRUCTED DURING THAT TIME WHEN TECHNOLOGY WAS NOT THAT MUCH HIGHLY DEVELOPED. BUT IN THE CURRENT TECHNOLOGY REGIME IT IS EASY TO DEAL WITH SUCH HAZARD AND TREAT IN PURVIEW OF SEISMIC FORCES. SO THIS KIND OF TECHNICAL CLUE SHOULD NOT BE A BASE FOR POLITICAL LEADERS FOR DELAYS.
EJAZ KARIM GEOLOGIST GEO-HAZARDS
Bash Dam is very vital for the devleopment of Gilgit-Baltistan,especially for Pakistan. Indian are constructing Dam every other day but all is OK, no fault line or so & so. It is conspiracy to keep Pakistan dry. Hope people will being partiatic & Pakistani, and come forward to help constructing the Bash Dam.