The
NDMA daily report for today (22nd July) reports a dramatic decrease in lake level - 19 inches (48 cm) in the last 24 hours. This is by far the largest fall recorded to date, producing a lake level the looks like this:
This is quite surprising. Assuming that the surface area of the lake is 1202 hectares (in fact it is probably a little larger in reality), this implies that about 5.8 million cubic metres of water has left the lake in the last 24 hours, representing a rate of about 67 cubic metres per second. However, the reported spillway discharge has not increased substantially - discharge at Ganish Bridge was 20,800 cubic feet per second yesterday and 20,837 cubic feet per second today.
So what is going on? Well it could be a measurement error, perhaps of the discharge. Alternatively it could be that the inflow has dramatically reduced, maybe because the weather has cooled.
Either way it is a surprising observation.
Finally, I somehow missed until today this low resolution image published in the
Pamir Times a few days ago of the dam:
I am astonished at how much downstream erosion there has been since I last saw an image of the site.
Comments and thoughts welcome please.
Hmm...maybe there is a blockage upstream in the river - less inflow? Just speculation!
ReplyDeleteThank you for keeping us informed and doing such a great job in putting the various jigsaw pieces - however incomplete - togehter to make sense. That is a blessing!
A highly tantalising photo. Yes, there's downstream erosion, but there's next to nothing visible in the upstream portion; so, left in dark.
ReplyDeleteThe only thing that can be said is that the upstream portion seems to be changing very little compared to downstream.
George
Could the water have gotten high enough, or heavy enough, to find another exit? Another valley, a cavern, a sinkhole?
ReplyDeleteKeep in mind that I am a complete novice, know nothing about the terrain, and am just brainstorming here. In fact, if you know of a book about fluid dynamics for non-engineers or even children, I have been looking for one.
Your blogs are fascinating, and I have learned a great deal from them. Besides landslides, they have increased my awareness of other cultures. I literally knew more about Saturn's moons than I did about Pakistan, before this.
Thank you for sharing your knowledge, and please keep writing.
Temperature in northern Pakistan has dropped by 15-20 Degrees Celsius in past days and is consistently low.
ReplyDelete