Wednesday, 26 May 2010
The combined monitoring effort appears now to be providing consistent measurements of the remaining freeboard, and these are now being used in the media, which is helpful. As of late last night the reported freeboard was 8.8 feet, which is 2.56 metres. This provides a freeboard – time graph that looks like this:
This suggests that we are still on course for overtopping on about 27th or 28th May, although clearly this remains a moving target for all the reasons previously outlined.
Meanwhile, the media in Pakistan have now picked up on the inconsistencies in the measurements reported by NDMA, and in particular their incorrect measurements of freeboard. This article is strongly critical of the error by the government agencies.
The state of the spillway is also a concern now within Pakistan. From the same article:
The engineers said the 25-metre-deep spillway was too narrow to accommodate outflows of more than 2,400 cusecs from the lake, which held an estimated 1.2 million cusecs on May 17. A cusec is a unit of water flow equal to one cubit foot per second. “There is a serious possibility that the entry of water into the spillway could trigger a collapse of debris that would block it altogether,” an engineer said.
Several people have asked why the slopes on the sides of the spillway are failing given that the weather is dry. The answer I think lies in the material – which dries on the surface but remains wet and very weak just below – and the loading from the excavated materials on the slopes above the spillway:
The Sinking Paradise-Video