Kulman Ghising on the lessons Nepal must learn from the hydropower disaster

The Bhotekoshi disaster exposed how vulnerable Nepal’s hydropower infrastructure can become when rivers, glaciers and underground facilities are hit by extreme events. The disaster caused extensive damage to 13 hydropower projects and transmission facilities in Rasuwa and Nuwakot, while reports said 934 people working at the sites were out of contact in its immediate aftermath.

Kulman Ghising, a former managing director of the Nepal Electricity Authority and chairperson of the Ujyalo Nepal Party, said the risks have grown because of melting glaciers, expanding glacial lakes and sudden flash floods or cloudbursts. Hydropower plants are usually built along riverbanks because of Nepal’s geography, but that location can leave powerhouses, access tunnels and other structures exposed to inundation.

Ghising stressed that hydropower tunnels cannot be treated like road tunnels. Hydropower tunnels divert water from headworks to an underground powerhouse, while road tunnels carry vehicles. The system also includes desander basins, surge tanks, penstock pipes, cable tunnels and tailrace tunnels. Outdoor desander structures, he said, face greater danger during floods and other natural disasters.

Powerhouses are built inside large mountain caverns. A powerhouse at Rasuwagadhi, for example, has a cavern about 75 metres long and 15 to 20 metres wide. Access tunnels may enter 10 to 60 metres above the riverbed, depending on the terrain and river level. At Trishuli-3A, however, the lowest tailrace tunnel and two entry tunnels were buried, along with the cable tunnel. The powerhouse became completely sealed, without airflow, although two engineers were rescued through the cable tunnel. The incident has raised urgent questions about tunnel design, access, rescue coordination and future safety measures.