ہنزہ میں بننے والی مصنوعی جھیل کے اچانک پھٹ جانے سے بڑی تباہی کا خدشہ ہے۔ ماہرین

The News - Even after 90 per cent of excavation work, the risk of sudden water outburst in newly developed large lake due to blockage of the River Hunza after massive landslide is still haunting the relevant departments as it can pose danger not only to thousands of people but also to Tarbela Dam, 50 kilometres northwest of Islamabad, sources told this scribe here on Friday. 

According to sources, the National Disaster Management Authority (NDMA) and other departments, currently engaged in construction of spillways, took many weeks to remove major portions of debris and other material from the lake because engineers avoided use of heavy machinery or dynamites in the face of critical situation. 

Sources stated that the relevant departments tried to complete construction of spillways till May 30, as signalled by various officials of the Ministry of Environment, but now they would take further two weeks for completion of their task. 

The high-ups of all relevant departments during a meeting held under the chairmanship of Environment Minister Hameedullah Jan Afridi unanimously decided that no major blast technique would be used to clear the way of the River Hunza and instead spillways would be constructed for drainage of accumulated water. 

The report presented by Professor David Petley of the International Landslide Centre at Durham University clearly stated that there was a substantive risk of water outburst with a potential for a large flood wave to travel downstream as far as Tarbela Dam, 50 kilometres northwest of Islamabad. 

In his report, he stated that there was a substantive risk of an outburst event caused by the landslide dam in Hunza that was most likely during or shortly after water travelled across the spillway. However, such an event can be triggered by a range of other processes, some of which may provide little warning. 

“If such an event occurs, there is the potential for a large flood wave to travel downstream as far as Tarbela Dam. This wave would greatly endanger the downstream population and can cause damage to infrastructure,” it said. 

The report further stated that populations located between the river level and the safe level should be evacuated prior to the arrival of the wave. It would require precautionary evacuations for those people living downstream of the dam and emergency evacuation plans for those living further downstream. 

It suggested that a great deal of more work was urgently required in terms of the management of the hazard, in particular outside of the area between Attabad and Gilgit while constructing spillways for drainage of water. 

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 kilometres long where water level has now increased up to 300 feet. The initial disaster buried the village of Attabad and submerged three miles of the Karakoram Highway, highly important for business activities in the summer season. 

An expert from Geological Survey of Pakistan has already informed the Ministry of Environment 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 Hindukush mountain ranges meet. 

Arshad H. Abbasi, a visiting research fellow at SDPI, said if the water goes out of the lake it would reach Tarbela Dam because the water waves can be as high as 40 metres or even more due to huge body of water behind a landslide dam. 

FOCUS Pakistan that conducts regular geological survey and hazard assessments of vulnerable areas especially in the mountainous areas of northern Pakistan in its assessment report compiled in 2006 stated that there was a high risk of rapid movements and potential disaster but no one took pains to take any precautionary measure that resulted in massive landslide in the Hunza River. 

The data provided by FOCUS showed that it has set up an early-warning system to alert villagers downstream in case the dam shows signs of collapse. A monitoring camp has also been set up above the lake equipped with CCTV and floodlights to monitor seepage or any unusual activity in the dam. 

National Disaster Management Authority (NDMA) Spokesman Ahmad Kamal told this scribe that clearance of area or preparation of access way on slide for making spillway cut started on January 6 and 180,104 cubic meter excavation work has so far been carried out by the Frontier Works Organisation (FWO) that is almost 91% of total excavation work. 

“You cannot go for adventure when level of water increasing constantly and there is a danger of sudden water outburst, so there is a need to take every step with extreme care to ensure every thing moves in the right direction,” he said.

Giving details about newly developed lake, he said, the length of the lake is 12 kilometres and its height has reached up to 282 feet and current water inflow is 1,894 cusecs having seepage of 32 cusecs.