A second debris-dammed lake is outflowing above the Himalayan valley crews are still searching

The number in circulation is storage, a measure of volume. What injures people downstream is the rate at which that storage drains, and nobody has published a peak discharge for the reach where crews are working. A few million cubic metres sitting behind avalanche debris ^[9] becomes dangerous through that release rate. The conversion into roughly 1,200 Olympic pools ^[10] is a volume, not a hydrograph.

The geometry is more informative, but it needs unpacking. If the lake surface is at 2,950 metres and about 1,000 metres above Gyirong Port ^[7], the port sits near 1,950 metres ^[15], and spread over the more than 10 kilometres CCTV put between barrier and port ^[6] that is an average grade of at most one in ten ^[16]. That is not a gentle profile. It also measures something different from Zhang's description of a valley section with limited elevation drop ^[9], which refers to the ground immediately around the impoundment rather than the whole run to the border crossing. The record as supplied does not reconcile the two, and the difference matters: gradient is what converts stored water into velocity.

"Has begun to outflow" ^[8] describes two very different futures. Water crossing a debris barrier can cut a channel that stabilises and lets the lake down over days, or it can erode the crest and carry the barrier away with the release. The source material does not say which process is underway, and that distinction is most of the forecast. Satellite imagery and preliminary assessment ^[2] can establish that a lake exists and is growing. It does not give depth, dam composition, or freeboard, which is why the volume arrives as "a few million" rather than a figure with an error bar.

The hazard is also plural. Several small water bodies formed after Wednesday's collapse ^[11], and Steiner points to melt continuing under high temperatures with debris and rock still lying in the channel ^[12]. Watching the one lake that has been imaged says little about the next blockage assembling somewhere else in the same debris field.

On severity, both scientists tracking the situation declined the escalation: the alerts deserve to be taken seriously because rescuers are exposed, and a flood as devastating as Wednesday's is unlikely to recur ^[13]. That is a statement about magnitude. Safety is a separate question, and the two diverge when the exposed population is standing in the channel. With hundreds dead and more than 1,500 people missing ^[14], searching will continue inside the footprint. What would make the standing order useful is a published interval between detection upstream and evacuation on the ground; without it, "move to a safe location if necessary" ^[3] leaves the timing judgment with whoever is holding the shovel.