10 February 2010
Continuing works on the Attabad landslide
Posted by Dave Petley
The National Disaster Management Authority in Pakistan is posting daily updates on the situation with the Attabad landslide on its website here. The reports appear with a lag of about 4 days, but nonetheless provide a helpful insight into the rate of progress. As of 6th Feb a total of 26,000 cubic metres of debris had been moved to create the spillway. Meanwhile the lake level is increasing at 60 cm per day – it will be interesting to see if this rate decreases with the recent weather.
This impressive rate of progress appears to be possible because the area that they are excavating is very fine-grained, as this video shows:
Meanwhile, the ever helpful Pamir Times reports that the river blockage is starting to have substantive impacts downstream due to the reduced flow levels. These impacts are clearly most acute directly below the dam, where the river is now dry, but extend right down to the Tarbela dam, close to Islamabad.
In view of the situation what could be the solution for release of water from the dam. The villages, particularly Ayeenabad and Shishakat and Gojal in generally, on upper stream of dam are submerging with every passing second. The inhabitants of above mentioned villages are traumatized. Every one is guessing there own but an expert opinion yet not developed and informed to the people up to their satisfaction. In order to boost the morale of the disaster hit people you are requested to give us your expert opinion when the dam will be filled and to what level the above mentioned villages will be submerged. To what extent the losses could be expected, if dam bursts suddenly. Further, what type of rights could it be claimed by natural calamity hit people under the UN resolution.
"This impressive rate of progress appears to be possible because the area that they are excavating is very fine-grained, as this video shows…"Do fine-grained soils have a greater chance for sudden failure?
The efforts currently being made will only bring forward the overflow date and diminish the volume of water released when the dam ultimately breaches and fails. The material shown being excavated looks too erodible to withstand teh overflow. Effort would be better spent forming a spillway with armoured rock lining using the large blocks visible. Jeff