24 May 2010
A further update on Attabad
Posted by Dave Petley
Important update: a combined Focus and FWO team have now resurveyed the freeboard and have agreed that there correct freeboard figure was 11.5 feet (3.5 metres) this morning. This means that overtopping is likely to be a few more days away, although failure could still occur at any time.
NDMA have now released their daily report for yesterday, so I have replotted the freeboard graph (see note above):
You will see that there has been further divergence between the Focus and the NDMA data, with NDMA still reporting 2.01 metres of freeboard, and representing a decrease of freeboard of just 43 cm in 24 hours. On that basis, the overtopping may still be a few days away. It should be noted here that the NDMA freeboard was physically measured, whilst the Focus figure was estimated from a distance. On that basis it may well be that the NDMA data are more reliable.
NDMA have now suspended freeboard measurements, quite rightly, so we are all in the dark from here-on.
hello Prof. David,thanks for the update.any estimate of the volume of the lake? Is it around 620 million m3 corresponding to 2454m spillway maximum inverts level, if we use SRTM dem data?Can you please give some more detail about the debris/soil properties? at some point FWO had to stop the excavation for some time as their machines could not work in muddy/swampy conditions.
An extremely rough estimate of the lake would be 22km long x 500m wide x average depth 55m (min depth 0m, max depth 110m) = 605 million m3. Which is about the same as Banqiao Dam.
Dr Petley,I want to thank you for your effort monitoring the Attabad landslide disaster. Your blog has been very educational to me in understanding the scale of this calamity. I have referred to you in a Opinion piece that I wrote in a local paper here last weekend; the link is http://tribune.com.pk/story/15110/a-catastrophe-of-epic-proportions/ and http://tribune.com.pk/story/15381/a-catastrophe-of-epic-proportions-2/.I hope the government will take heed. The effort on the ground at the moment seems to be inadequate for the scale of the flood that may be expected. God preserve us.