Monday, June 7, 2010

Latest image of the spillway at Attabad

The wonderful people at Focus have provided an image of the state of the spillway at Attabad that is very instructive.  This was taken today:


The current state of play is I think as follows.  Flow appears to be constrained by two blockages but, as a commenter has noted, one is a rock spur out of the channel.  The blockage appears to have formed a small waterfall / rapid.  Downstream of the blockage the channel has widened dramatically - and indeed a section of the track has now been lost.

To me this suggests that the crisis may be far from being over.  In particular, the loss of this barrier could cause a rapid increase in flow rate that could be highly erosive.  It is however important to stress that interpreting the state of play from photos is difficult.

4 comments:

  1. Hi Dave,
    I've been following all this from New Zealand. I travelled up here in 1978 while I was working on the Tarbela Dam.
    Looking at some of the larger rocks above the channel.. These would seem to be useful to break up the flow if they could be moved to the channel.

    David

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  2. I think those two rocks are not the culprits. actually the four lined up rocks close to the bottom of the photo are actually resisting further erosion. Deeper erosion along those four rocks may lead to collaps of those two roack up the spillway and i am sure there might be other rocks bellow those four working as anti erosion support. i think inducing erosion manually required.i think inducing erosion manually required.

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  3. My concern is the mouth of the spillway. I do not think it has widened and deepened for a few days. I was following news and one TV Channel Dunya reported that there were experts suggesting mechanical/demolition methods to widen/deepen it. Remember the query I raised on 8:30 update. Here it is.

    [We have to consider that it is mostly the overflow that is getting into the course of the spillway. If the spillway does not widen, it will neither deepen. I am certain that leaving it as a fait accompli as an Act of God (endemic in Pakistan)will only make the Lake wider and longer upstream. A time will come when it hits the Glaciers. It will then be disastrous.
    Some sort of mechanical or explosive earthworks are needed to deepen the spillway and remove barriers like boulders etc.

    Engineers and geologists have to keep options in hand due to constant land slides etc.]

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