WhatsApp engineers guide Nepal's desperate search through flood-buried hydropower tunnels

On August 26, a wall of water, mud, and rock tore down the Trishuli valley in Nepal, collapsing a glacier and unleashing a flood that killed more than 1,200 people. The deluge buried six hydropower plants—at least three still under construction—under 2.2 million tonnes of debris. About 900 workers from those facilities vanished. In the days that followed, rescue teams faced an almost impossible task: finding anyone who might have survived inside tunnels designed to channel water or provide access to the plants, now entombed beneath rock and soil.

Before the flood struck, engineers working on the hydropower projects had created a WhatsApp group to coordinate their work. After the disaster, that group became something else entirely: a lifeline for rescuers. The chat expanded to more than 500 members—government officials, military personnel, hydropower company staff, and technical experts—all working in real time to guide search teams through tunnel networks that no longer resembled their original design. When a government official typed into the group asking for layout drawings of the Chilime plant, a response came back within minutes: detailed schematics of the powerhouse and access tunnels. Similar exchanges followed as rescuers sought guidance on tunnel locations, dimensions, and structural details that might help them navigate the buried infrastructure.

The challenge was immense. The flood had not simply closed the tunnels; it had transformed them. Mud, rocks, soil, and debris had accumulated inside. Entrances were buried under metres of material. At Rasuwagadhi hydropower plant, rescue workers pushed 250 metres into one tunnel before hitting a complete blockage. Yet they kept trying. Officials believed that 46 people might be trapped in a chamber at that site, possibly with access to food and water. At Upper Trishuli 3A, it took almost six days just to reach the tunnel entrance because it was so thoroughly buried. Once there, rescue teams began trying to pump oxygen through pipes into any cavities where survivors might be sheltering.

Some workers had already escaped by understanding the tunnel systems. Jan Jiwan Thakur, a civil engineer at Upper Trishuli 1, was warned moments before the flood arrived. He and about 100 others from the facility ran uphill and survived. Dhan Bahadur Tamang made it out through a tunnel at the same plant, navigating in darkness as pipes and equipment rushed past him. He saw dead bodies during his subterranean escape. Others were not so fortunate. The Nepal Independent Power Producers' Association reported that at least eight people could be trapped at Chilime. No one had been found alive in any of the tunnels by the time rescue efforts were well underway.

On the WhatsApp group, members posted names and phone numbers of missing workers, asking government officials to pass them to telecom authorities in hopes of locating their last recorded positions. The group became a repository of technical knowledge and human desperation at once. A manager at the Nepal Electricity Authority, speaking anonymously, confirmed that rescue workers had asked former plant employees for advice about tunnel layouts through the chat. The drawings shared there had proven useful.

The flood wiped out 10 per cent of Nepal's entire power generation capacity. More than 4,000 people remained missing across the country. But for the families of the 900 missing from the hydropower plants, the focus was narrower and more intimate. Rajesh Shrestha, who runs a workshop making window grills, waited for news of his 30-year-old son, Rajish, an environmental engineer at Upper Trishuli 1. "Whenever I look outside, I imagine seeing him carrying a bag and coming home, just as he used to," Shrestha said. "I am surviving on the hope that he will return." Rescue teams continued their work in the tunnels, guided by engineers typing coordinates and advice into their phones, searching for anyone who might still be alive in the darkness below.