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 still be alive inside tunnels of devastated hydropower plants. The messaging group was set up by engineers before a wall of water, mud, and rock crashed down the Trishuli valley in Nepal on August 26, and it has since become a valuable tool alongside helicopters and heavy machinery in the ongoing race to find survivors.

The authorities hope that some of the roughly 900 people reported missing from six hydropower plants, at least three of which were under construction, may have escaped the deluge because they were working inside or fled into the tunnels at the time of the disaster. Even locating the entrances to some of these tunnels, which were originally designed to channel water or provide access to hydropower facilities, has proven extremely difficult, after the flood deposited an estimated 2.2 million tonnes of mud and debris down the valley, according to Reuters reporting.

Alongside the Chilime hydropower site, rescue workers are searching five other hydroelectric locations in the valley, all part of an expanding network of plants that supply electricity to the nation and export surplus power abroad. The flood is reported to have wiped out roughly 10 percent of Nepal's total power generation capacity, underscoring the scale of the disaster's impact on the country's energy infrastructure in addition to the human toll. At the Rasuwagadhi hydropower plant, rescue workers managed to push 250 metres into one tunnel before encountering a blockage, though they have not abandoned the search.

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"We are trying to reach there inside again to look for people," said Amshu Kiran Shahi, a board member of the Nepal Electricity Authority, adding that as many as 46 people may be trapped in an internal chamber where they could potentially have access to food and water. A manager at the Nepal Electricity Authority, speaking on condition of anonymity, said rescue teams had also sought advice from former plant employees regarding the layout of the tunnel networks through the WhatsApp group, noting that technical drawings shared within the group had proven useful to the search effort.

The human toll of the disaster has been significant. According to Reuters, the August 26 flash flood, which was triggered by a glacier collapse, has killed more than 1,200 people, with more than 4,000 individuals still unaccounted for as the search continues more than a week later. Among those awaiting news of missing loved ones is Rajesh Shrestha, whose 30-year-old son, Rajish, an environmental engineer at the Upper Trishuli 1 project, remains unaccounted for. "Whenever I look outside, I imagine seeing him carrying a bag and coming home, just as he used to," Shrestha said.

The reliance on a coordinated, engineer-led WhatsApp network illustrates the improvised yet increasingly vital role that digital communication tools are playing in disaster response efforts in Nepal, particularly in situations where physical access to affected sites remains severely limited. As excavation and search efforts continue, officials and rescue teams are likely to keep leaning on such informal expert networks to navigate the technical complexities of the damaged tunnel systems in the days ahead.

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