Miracle rescue of workers in Nepal tunnel

An army of experts in a WhatsApp group is guiding rescue workers scouring a Nepali valley after a huge flash flood more than a week ago as they desperately search for anyone who may be alive inside tunnels of devastated hydropower plants.

The messaging group was set up by engineers before the wall of water, mud and rock crashed down the Trishuli valley in Nepal on August 26. It has since become a valuable tool alongside helicopters and heavy machinery in the race to find survivors.

The authorities hope some of the about 900 people reported missing from six hydropower plants - at least three of which were under construction - may have escaped the deluge because they worked in or fled into the tunnels.

In a first sign of success, two people were brought out alive from a tunnel linked to the Upper Trishuli 3A hydropower plant on Friday, nine days after the disaster, a lawmaker said.

Even finding entrances to some of the tunnels, which were designed to channel water or used to access hydropower facilities, is tough now after the flood deposited 2.2 million tonnes of mud and debris down the valley.

"Can you send me Chilime layout drawings," a government official wrote on the engineers' WhatsApp group on Saturday as rescue workers searched the buried remains of the Chilime hydropower plant high in the Himalayan valley close to the Chinese border.

Minutes afterwards, a member of the group chat, which was expanded to add more experts in support of the rescue effort, responded by sending drawings of the project's powerhouse, as well as details of access tunnels.

That exchange and others posted on the group, which has more than 500 members, were seen by Reuters.

Nepal's Independent Power Producers' Association said on Monday at least eight people could be trapped at Chilime, while an official at the Nepal Electricity Authority said 46 may be trapped at Rasuwagadhi hydropower plant, further south.

Reuters spoke to a dozen people - including government and military officials, engineers, survivors and relatives of missing workers - who described the efforts to search the tunnel networks of ruined hydropower plants, including how real-time guidance was being provided by experts over WhatsApp.

"The flood has altered the terrain around the tunnels and changed their structure, while mud, rocks, soil and other debris had accumulated inside," Nepal army spokesperson Raja Ram Basnet told Reuters. "This is not a normal closure of tunnels."

At Chilime, Reuters images on Monday showed a large tunnel entrance with flood debris rising to the ceiling a short way inside.

More than 1,200 people were killed in last week's deluge caused by a glacier collapse. More than 4,000 people are still missing, including those who might be trapped inside tunnels.