Caution, Peacefull drainage from Hunza Lake may not remain a reality

By: Jeffery Kargel

American: A smooth and peaceful drainage of the lake remains a hope. But it is not likely to remain a reality. Scientific predictions had stated all along that the most likely scenario would be a slow increase of water flow up to a point when erosion starts to be significant–my educated guess is around a thousand cusecs. Then erosion will deepen the channel even while inflow continues to add water faster than it flows out. In that situation, the flow will dramatically increase and likely will reach a runaway extreme flow, which will erode further, and cause the lake to drain fully or in part. The time required for the spillway to become erosive may have been as brief as ten hours, but this was not the case. Similar situations usually have a period of 1, 2, or 3 days before flow goes really wild. There may be a period when flow increases dramatically, but not catastrophically, and then stabilizes for a while. So long as there is substantial water in the lake, residents should not venture down to watch the flow. Erosion of this type of dam particularly (made of several different types of material) can be extremely irregular. What seems to be a smooth discharge one moment may become completely uncontrolled 10 minutes later. This is what we normally would expect. So please be wary. Hope is a good thing. So is wariness in such situations. Best wishes, from an American to the good people of Hunza. A smooth and peaceful drainage of the lake remains a hope. But it is not likely to remain a reality. Scientific predictions had stated all along that the most likely scenario would be a slow increase of water flow up to a point when erosion starts to be significant–my educated guess is around a thousand cusecs. Then erosion will deepen the channel even while inflow continues to add water faster than it flows out. In that situation, the flow will dramatically increase and likely will reach a runaway extreme flow, which will erode further, and cause the lake to drain fully or in part. The time required for the spillway to become erosive may have been as brief as ten hours, but this was not the case. Similar situations usually have a period of 1, 2, or 3 days before flow goes really wild. There may be a period when flow increases dramatically, but not catastrophically, and then stabilizes for a while. So long as there is substantial water in the lake, residents should not venture down to watch the flow. Erosion of this type of dam particularly (made of several different types of material) can be extremely irregular. What seems to be a smooth discharge one moment may become completely uncontrolled 10 minutes later. This is what we normally would expect. So please be wary. Hope is a good thing. So is wariness in such situations. Best wishes, from an American to the good people of Hunza. jeffreyskargel@hotmail.com Jeffrey Kargel http://www.glims.org 0

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