Allowing for the slight change in camera angle, there is little indication of major change between the two images. The large boulder on the left side of the upper part of the channel bank has slipped into the water on the right hand image, presumably indicating that channel widening is continuing. Of course there may well be some continued erosion of the bed that would is not visible here.
In the upper channel there is comparably little evidence of change also. The inset image is from 7th June, the main image a day later:
It may be that a more detailed inspection on the ground would reveal a more dynamic system.
It is my intention to stop duplicating posts on the two sites from today, with the Hunza Monitoring Blog being used once again to present data on the state of the dam and the lake, and Dave's Landslide Blog to provide a commentary. On DLB I will also start covering other landslide events again.
What is the slope from the inlet to, for instance, the end of the now-mostly-vanished bulldozed slope?
ReplyDeleteWhat has my attention are the apparently shrinking mounds on the right side opposite the blocking boulders. I wonder how much is being carried away not by the stream per se, but by hidden flows under the right side. If they are present, and they do propagate upstream, then it seems that the outflow could increase quite quickly.
That said, I have been continually surprised at how uneventful this overtopping has been. How long before we decide that the spillway's engineers did a great job?
Worth mentioning: Dave's red-lined photo predictions have been largely fulfilled.
"How long before we decide that the spillway's engineers did a great job?"
ReplyDeleteIf you are talking about humans, then never is probably too soon. If you are talking some natural engineering of constructing the dam with large boulders, then maybe.
I'd like to see some scientific evidence that suggests that human action kept this dam up this long. It'd be my guess that if the dam were not excavated, these events would be basically the same. But the residents of the area would not have been happy.
The underwater boulder at the top river right of the bottleneck appears to have turned clockwise and the right bank imediately below it has given away so that water is now flowing both sides and over the boulder.
ReplyDeleteMore erosion right of this boulder looks like where the channel could evolve. The boulder could continue to slide or rotate depending on what it rests upon. At this high point in the channel there is little more than static pressure against this boulder as the water above has only dropped a small amount.
The smooth water over the top of the boulder indicates an acute triangle with its apex near the right bank. Limestone (if that is what it is) in water can get quite slippery.
George