10 June 2010

Attabad spillway video

Posted by Dave Petley

Thanks to a number of people for drawing my attention to the Hunzaonline video on youtube that shows the spillway in action.  The caption indicates that this was collected on the 8th June:

Three observations about this video:

  1. It shows that the major restriction on flow is still the large boulder at the saddle of the spillway;
  2. A second boulder has formed  substantive constriction downstream as well, but this is not controlling the overall flow
  3. There is still considerable scour occurring, especially on the downstream side of the boulder, upstream of the boulder towards the neck of the channel, and elsewhere on the banks of the channel.

Meanwhile, the Pamir Times reports that “An international expert reportedly suggested the government to blow two large boulders present in the spillway but the government has decided to act against the suggestion“.

In case anyone was wondering, that expert is not me!   Whilst I wouldn’t completely rule out the possibility of a controlled blast, this would need to be undertaken with extreme care, and only after a full analysis of the consequences had been undertaken.  I would in particular want to see an evaluation of the likely flood that the blast might trigger, and the potential for triggering further slides on the sides of the valley.  However, this is not an excuse for inaction – NDMA really need to move quickly now to evaluate the range of options, and to communicate the pros and cons more widely.

As per my post yesterday, I will use the Hunza Monitoring Site to host updates on the situation at Attabad, and this site to provide a commentary.  I will put a new set of data on the monitoring blog later this morning.