29 May 2010

Attabad: initial flow established

Posted by Dave Petley

Please note that it is hard for me to keep up to date with this evolving situation.  If you are potentially-affected by this hazard please use the formal channels of communication set up by the government.  Do not rely on this blog to provide warnings.

Flow through the spillway is now properly established and is increasing with time.  The latest NDMA report suggests that flow is 300 cubic feet per second (8.5 cumecs), which sounds surprisingly high – indeed I am sceptical of this figure.  UPDATE: The Pamir Times is reporting 25 cubic feet per second (0.71 cumecs).  this figure sounds more sensible.   Reports suggest that so far the flow is stable.

So where does this leave us? Well, as I suggested this morning, erosion is likely to take a while to develop, so we are far from out of the woods as yet.  Some lateral erosion at this stage might be helpful in widening the channel, increasing its capacity.  However, as the flow increases the chances of the channel becoming blocked will slowly reduce, but again it is too early to eliminate this possibility.  As flow increases the potential for erosion also rises, so for me the critical period is from now until the point at which outflow = inflow.  This point is some days away.

It is clear that the authorities are taking this very seriously now, with helicopter surveillance in addition to the land-based monitoring.  This is good to hear.