PARIS (AFP) - Rescue teams searching for survivors of a deadly flash near the border between Nepal and Tibet were forced to stop their work on Friday after water overran the banks of a lake formed by mountains of debris upstream of the flood zone.
While rescuers were later able to resume their search, the spectre of a fresh onslaught of water rolling over those who rushed to the remote Himalayan region to help in the wake of the catastrophe hammered home the vast challenges facing the rescue teams.
Police in Nepal on Friday said at least 552 people had been killed in the disaster. Chinese authorities on Friday raised the death toll in Tibet from three people to five. More than 1,400 people are still missing.
Nepalese and Chinese authorities have vowed to use all the means at their disposal to help those affected.
The overflowing “barrier lake” is one of two bodies of water formed by the torrents of mud and rubble carried away by the flood, according to an official with Nepal’s Disaster Management Authority. The official added that both lakes would continue to pose a flood risk until the water had fully drained – particularly in light of the torrential rains that are expected in coming days.  
Simon Cook, a glaciologist at the University of Dundee, said the risk of further flooding looked all too real.   
“This dam is just made of loose rock and mud and so on, it’s not a carefully engineered dam that you might have for a reservoir or a hydropower project – it’s just loose debris holding back presumably many million cubic meters of water,” he said. “And the worry is that as more water enters that lake, it either overpowers the dam because the dam is just not strong enough to hold it, or it overtops the dam and cuts a notch through the dam material. And then once it starts cutting into that dam, the whole thing could be released.”
For rescuers locked in a race against time to recover as many survivors as possible, the conditions are far from ideal. 
“I would definitely classify this as one of the more complicated rescue missions there is,” said Daniel Nohrstedt, a specialist in crisis management following natural disasters at the University of Uppsala in Sweden.
Researchers said the region’s rugged terrain and the wet forecast are first and foremost among the steep obstacles that rescue crews must grapple with.