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2 June 2010
Attabad – so why hasn't it breached yet?
Several people have emailed to ask why the lake has yet to breach. Well, I would like to emphasise two things – first, that every landslide is different, so predicting the behaviour of any particular slide is effectively impossible. Second, there is a peculiarity about the spillway that appears to be delaying the breach event. Regular readers (of which there are now several thousand each day I think – thanks …
Attabad – flow continues to increase with time
The Pamir Times reports that as of lunchtime today the flow through the spillway had increased to about 850 cubic feet per second – i.e. 24 cubic metres per second, giving a discharge – time graph that looks like this: For the last 72 hours or so the increase in discharge with time appears to have been linear, which is interesting. This suggests that erosion of the saddle has yet …
1 June 2010
Attabad – continued retrogression. Close to the next stage?
The latest images from Attabad suggest that the retrogressive erosion in the channel continues to accelerate, and that this is now by far the most likely failure mechanism. A breach now looks to me to be inevitable. This image, taken this afternoon, shows how the spillway has developed: Note the people on the road for scale. Compare it with yesterday’s image: The waterfall has now smoothed out, probably because the …
Attabad – further retrogressive erosion
The latest photos from the site, taken late yesterday, show that the retrogressive erosion of the channel is continuing to develop rapidly. This image was taken at about 5 pm yesterday: The lower part of the channel has widened and, more importantly, the steep section has moved up channel considerably. Bear in mind that this image is more than 15 hours old now. The best illustration of the way that …
31 May 2010
Attabad: flow and erosion are continuing to develop
Flow through the spillway at Attabad has continued to develop during the day. However, as I suggested in my post this morning, some of the higher discharge values being quoted are without foundation. At 6 pm the discharge was about 360 cubic feet per second (10.2 cubic metres per second). Thus, the discharge graph looks like this: At the moment there appears to be little evidence from these figures that …
30 May 2010
Retrogressive erosion at Attabad
Flow continues to increase at Attabad. Inflow is still exceeding outflow and seepage, so the lake level continues to rise, to the detriment of the upstream communities. There has been some confusion about the statistics about outflow – it is now clear that NDMA discussions often use the combined spillway plus seepage figure, but that this is interpreted by the media as being the spillway flow. According to the NDMA …
Reported increases in spillway flow at Attabad
If you live in the Hunza and Indus valleys, please do not rely upon this blog to provide warnings and up to date information. Using only reliable reports in the media (mostly information from the Pamir Times) and those from NDMA, the following graph shows the reported flow through the spillway at Attabad. There is a huge caveat here regarding the reliability of the reports. However, the most recent figure …
Attabad – flow on the spillway continues to develop slowly
Flow through the spillway continues to increase slowly. So far there are no signs of the development of a breach, but the amount of water passing through the spillway remains much less than the inflow. This image, taken yesterday morning, shows water passing through the channel: The difference between the flow in the channel and the amount of water coming through the dam as seepage (the large channel bottom right) …
Attabad overtopping – first image
The Daily Times has published the first picture of the spillway in operation: Meanwhile, the Pamir Times reports that: “The volume of water passing through the spillway has reportedly increased to around 50 Cusecs”. 50 Cusecs is 1.4 cubic metres per second. This is still a fraction of the total inflow, so we have a long way to go.
29 May 2010
Attabad: initial flow established
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 …
Dave Petley is the Vice-Chancellor of the University of Hull in the United Kingdom. His blog provides commentary and analysis of landslide events occurring worldwide, including the landslides themselves, latest research, and conferences and meetings.
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