Landslide Trigger

Leakage from the tunnel carrying water to Parbati II hydroelectric plant in Kullu is just one way how the project threatens the landslide-prone area.

- Ishan Kukreti

PRITHVI SINGH was half asleep in his house on a mountain slope on the evening of April 13 when he heard a loud rumbling sound and saw the roof develop a crack. There was water seeping out of the floor. Singh ran out of the house with his wife and two children and spent the night on the road. Six other houses in his village, Bhebal, in Himachal Pradesh’s Kullu district also developed cracks the same evening.

The landslide was not caused by natural tremors. It was triggered by water that had leaked the previous day during the testing of the head race tunnel (HRT) of the 800 MW Parbati II hydroelectric project. HRT is the tunnel that carries water to a dam’s powerhouse, and the over 30 km Parbati HRT is the longest for any hydropower project in India. It runs from Pulga village to Suind village (see ‘Shaky ground’), near which the powerhouse is located. The tunnel collects water from the Parbati river—a tributary of the Beas—and five perennial streams. The tunnel started leaking in its last stretch, near the powerhouse, when officials released water from just one stream, Jiwa nallah.

The leakage caused thin trails of water at random places in the area and a 500m crack to appear on the mountain above Bhebal. The situation is still precarious because the water that seeped into the mountain is trickling out from various points in the lower parts of the mountain and can cause landslides. Fourteen villages, including Bhebal, that come under the Raila panchayat now face the threat of a landslide.

Slow to react