Experts fear outburst may endanger Tarbela Dam

by Noor Aftab (The NEWS)

The construction work on spillways to gradually drain water from blocked Hunza River is unlikely to be completed before the last week of April thus raising fears of massive water outburst that can pose danger even to Tarbela Dam, sources told this scribe here on Thursday.

According to official record, the Hunza River near Attabad was blocked due to a landslide that occurred on January 4 this year. The landslide created a water reservoir 11 kms long and 223 feet high with 16.50 cusecs seepage of water. The initial disaster buried the village of Attabad and submerged three miles of the Karakoram Highway.

The input secured from the experts by the environment ministry clearly stated that in case of water outburst in Hunza River the water would sweep down from an altitude of nearly 2,500 meters, being replenished by first the Gilgit River and then the Indus, before hurtling down the narrow northern stretches of the Indus Valley towards the Tarbela Dam which is 40km north-west of Islamabad.

Arshad H. Abbasi, visiting research fellow at SDPI, told this correspondent that the Indus River is one of the world’s largest rivers in terms of water sediment loads and this massive debris (sedimentation) would have serious impact on Tarbala Dam, as it could completely dislodging the vast delta that dramatically expanded over the past decades at the mouth of the Indus. The reports prepared so far revealed that the landslide removed 120 meters of mountainside, destroyed the village of Attabad, killing 19 residents, isolated 25,000 residents upriver from the landslide-dam and severed a two-kilometre stretch of the Karakorum Highway, Pakistan’s only land link with China.

The temporary lake, fed by glacier water, has since grown dramatically, and now stretches 15km back from the blockage. The 900-metre-long mass of landslide debris that formed the lake is largely made up of powder-like sediments. British colonial records from the 19th century showed that two similar incidents caused flash floods that killed several thousands people and inundated huge areas of modern Pakistan.

An expert from Geological Survey of Pakistan has informed the environment ministry that the region is also among the most seismically active in the world because it is located at the junction of the Asian and Indian geological plates, where the Himalaya, Karakorum and Hindu Kush mountain ranges meet.

Abnormally high temperatures has increased water level in lake and a bridge across the Hunza River has also been submerged, disconnecting the settlements of Shaskat (or Shiskit) and Gulmit on the region’s only route to and from China.

National Project Director at the environment ministry Faiz who is heading the efforts to amicably tackle the situation told ‘The News’ that the decision to construct spillways to drain water from blocked Hunza River was taken after detailed discussion with all stakeholders. To a question about completion of spillways he said it is difficult to say that two spillways would be completed by mid-April because it seems that the construction work would continue till end of this month.

He said both spillways would be 40 meters wide and 30 meters deep that would help drain water from newly formed lake after landslide in the Hunza River.

Faiz said 25,000 people are being provided food through helicopters as road links are no more functional in some areas after the landslide.