Location: Dublin, Ireland. (No, I just live here.)
Posts: 654
The latest from Dr. Dave: the flow rate in the spillway has jumped markedly, and he thinks the situation is entering "the next stage". The lake level is still rising, so the outflow must inevitably increase, and with it comes wider erosion of the spillway. It looks like the spillway clay has been quite resistant to vertical erosion so far, but that might not last at higher flow velocities.
Not much information coming out of the region at the moment, though former Pakistani PM Nawaz Sharif was apparently there today, visiting people affected by the flooding.
Location: Dublin, Ireland. (No, I just live here.)
Posts: 654
In case anyone's wondering: it's been pretty quiet over the last week, with the spillway gradually eroding and allowing more water to flow.
However, that's not enough for some locals, whose homes were submerged under the lake. So they've broken through a police cordon with spades, and are widening the spillway themselves. Hunza affectees try to dig water spillway wider:
Quote:
The protesters complained that the administration instead of making a wide nullah only dug a narrow drainage from which water is flowing out at a slow pace. The demonstrators from Attabad broke through the police cordon to reach the spillway where victims from different areas of Gojal district who arrived there on boat joined them.
The victims managed to reach the scene despite closure of boat service and started plowing the spillway with spades and other tools they brought along with them.
History is replete with cautionary tales, the stories of those who screw around with forces that they cannot control ...
Unless the number of 'protesters' is significant I don't imagine that their efforts would have any noticeable effect (other than, perhaps, some of them falling in due to collapses - having made the edge unstable).
Location: Dublin, Ireland. (No, I just live here.)
Posts: 654
The Pamir Times has published some photos of the ... what do we call this? Militant Excavation? Spillway Seizure & Scooping? Lawless Lake Level Lowering Labour?
Looks like a typical construction site: more people standing around than working.
A good portion of those digging were tied to ropes held by those above. But there are cracks in the bank behind both digger and belayer so that if the bank slips, they all go in
Inane comment of the week award goes to the NDMA Regional Director who declared that this digging could trigger a flash flood -- reminds me of that Brown guy who was "in charge" during Katrina
Perhaps a parallel channel could be dug by bulldozers as there does seem to be areas on both banks where the trench would not have to be that deep.
The main problem seems to be that there's massive slabs that will not erode. The only thing that will remove them would be PGMs or a strong enough earthquake -- note that this is an earthquake prone region and that new reservoirs can trigger earthquakes, but that could be several years down the road or tomorrow.
This is really a political failure commensurate with Katrina in scale if not in lives affected. Advice and aid in the form of expertise and equipment was offered and rebuffed
There's press reports the police prevented the downstream people from reaching the dam and boats used to transport the upstream people to the dam have also been seized; also a report that the government has agreed to an expert panel to study expansion of the spillway.
But for the last six months the NDMA has rebuffed offers of help and expertise; so, little cause for optimism that they will suddenly get proactive.
Dr. Dave has posted information that summer flow will peak in late July at 2-3 times present flow.
If the banks are eroded past the edge of the underwater slabs at the top of the spillway downcutting could happen very quickly, but the banks at the top look like consolidated clay and rock, and the current velocity at the top is not that fast because the water has not yet dropped.
Reading how people above the artificial lake have tried to widen the spillway to reduce the water level where they live reminds me of this tale from West Germany.
In the 1960's (I think, may have been earlier) the River Rhein near Oppenheim (Hessen) burst its eastern bank while in flood. At this point the river passes Openheim on the left, which is located immediately on the banks of the river with a steep bluff behind; on the opposite bank a long and high dyke protects hundreds of square miles of low-lying farmland, and it was this dyke which broke.
People living in Oppenheim claimed to have seen rabbits running away immediately before the breach, and that it was their tunneling which caused the failure; however inhabitants of many villages such as Leeheim claimed the Oppenheimers had broken the dyke on the opposite bank to lower the water height and save their town.
We had a similar incident in the Tyne Valley in 2005 when an abnormal amount of water flowed down the river. Flood embankments built in the 1950s were overtopped and sections swept away. One of the causes of the breaches was due to percolation of water through the embankment by way of rabbit warrens that had been established over years of 'neglect' by the Environment Agency having ignored the obvious threat to the flood defences.
When the defences were breached the flood level subsided significantly within a few minutes from the peak (and stayed low - well, lower than the level achieved just before the overtopping and bank burst).
ISLAMABAD: The National Disaster Management Authority (NDMA) on Friday decided to use explosives to remove a rock halting the water outflow at the spillway at the accidentally-created Hunza Lake.
The NDMA Chairman, Lt-Gen (retd) Nadeem Ahmad, during a meeting, approved a proposal to use explosives for the removal of the rock at the entry point of the spillway, which is creating hurdles in water outflow from the lake.
“The rock would be removed through a minor blast in the next couple of days and that would hopefully increase the outflow from the present 6,400 cusecs to above 10,000 cusecs,” Gen Nadeem told The News here on Friday.
The NDMA chairman has reached Hunza for this special operation and a special team of Pakistan Army experts, led by Col Naseem, is expected to reach there today (Saturday).General Nadeem explained that the explosion will be minor in nature, adding that there was no other option than going for this minor surgical operation.
An official said if they adopt wait and see policy, then it may take them weeks or even months to drain water from the lake and it would be practically difficult to run the relief camps hosting some 30,000 affected people for such a long time.
He said the rock measuring 12x15 foot was a major hurdle in water outflow due to which there ratio of water inflow and outflow from the lake was the same.Major Adil of the NDMA, while talking to The News, said the decision about the removal of big rock had been taken in the meeting held on Friday and “obviously we would use explosives as there is no other way to do it.”
I don't imagine that simply removing the rock will have much immediate effect (though it might facilitate erosion that could deepen and widen the outflow).
IMO there needs to be a much broader spillway, but there is a point when the flow might increase exponentially.
The 'earth' appears to be clay, and the recent hot dry weather has baked it so that it is hard. Once water flows over the surface it will soften again and maybe start to 'dissolve'. Once erosion reached a crack (and there are several deep cracks) then chunks will get swept away. The trick is to avoid the flow escalating too quickly, yet increasing it so that the lake level actually falls.
This might take several more 'shots' of explosives. I cannot imagine that anyone would want to risk machinery to dig, especially with the possibility of further landslides.
The problem gets worse if the downstream dwellers give up and move back in to their settlements.
Edited to add:-
I notice that the NDMA personnel are:-
Quote:
The NDMA Chairman, Lt-Gen (retd) Nadeem Ahmad and The NDMA Spokesman, Brig Sajid Naeem
I wonder what qualifications (other than 'high office' in the military) they possess? Maybe you need a rank to be able to speak to the masses?
I suspect the "11x15" rock in question is the one at the left spillway entrance. Removing that particular rock will have next to no effect. The flow pattern where the water accelerates but is still blue is indicative of a massive streambed slab. The lake will not lower significantly until the upper slab(s) are removed or bypassed by natural or artificial process or combination thereof.
Explosives are what I suggested as a solution, some considerable time ago, and explosives are what is needed to increase the flow rate. It's obvious that because of the nature of the landslip material, a major, sudden and serious breach isn't going to happen in seconds, even with a major explosive charge. The clayey and rocky material, embedded with massive boulders, is providing a very stable wall for the water - not the unstable wall, as was first expected.
