Blueprint to protect landslide-prone Swiss village revealed

The stream of debris almost reached the village, © Keystone / Gian Ehrenzeller

Authorities have revealed the details of a drainage tunnel designed to stop the village of Brienz from sliding into the valley. 

On Monday, experts presented the tunnelling project proposed to give residents of the village in the southwestern Swiss canton of Graubünden some relief. Brienz/Brinzauls had recently made the headlines because of the threat of a landslide over the village in the Albula Valley that could have buried it. 

The village itself also stands on unstable rock and is sliding downhill at an increasing rate. To put the brakes, a drainage tunnel will be drilled into the mountain to west of the village. The aim is to extract water from the rock below the village which will help stabilise the surrounding area. 

“The tunnel is meant to stop the movement of the rock below the village and also that of the mountain above,” explained engineering geologist Reto Thöny at a press conference on Monday. 

According to the geologist, there is no comparable drainage project of its kind anywhere else. Nevertheless, the geologists and residents of Brienz/Brinzauls are optimistic that the landslide movements can be slowed down enough to keep the village habitable. 

“We are confident that the landslide will come to a complete halt,” said Daniel Albertin, mayor of Albula/Alvra municipality to which Brienz belongs.

An exploratory tunnel of 650m has already been drilled to give geologists and engineers a chance to test the plan. This will be extended by 1.6km and the entire project is estimated to cost CHF40 million ($45.5 million). 

Water flows from a borehole in the exploratory tunnel. © Keystone / Gian Ehrenzeller

Dramatic event

The huge landslide occurred at Brienz/Brinzauls in the early hours of Thursday, June 16. An estimated 1.5 million cubic meters of rock slid down the mountainside, narrowly avoiding the village. However, it covered a cantonal road and left a significant deposit in front of the school building. 

The 86 inhabitants were evacuated on May 12 after geology experts warned that a mass of two million cubic metres of rock looming over the village could break loose. They were only allowed to return almost two months later.