The landslide in the Graubünden mountain village of Brienz/Brinzauls is endangering tangible assets of up to 177 million francs. This is the conclusion of a risk analysis by the Canton of Graubünden. It is part of the investigations for the construction of a drainage tunnel, which is intended to technically repair the landslide.
The village of Brienz/Brinzauls with buildings, building land, roads and lines as well as three cantonal roads, several power and data lines and the Albula line of the Rhaetian Railway are located in the area of the Brienz slide in the municipality of Albula/Alvra, which has been moving downhill for several thousand years.
The construction of a drainage tunnel is intended to “technically rehabilitate” the landslide and slow it down to such an extent that the village of Brienz/Brinzauls can continue to be inhabited in the long term and the other infrastructures can continue to operate. When the canton or federal government grants subsidies for protection and remediation measures against natural hazards, they do so on the basis of forest legislation. This requires that protective measures must be effective on the one hand and also economically justifiable on the other.
In order to calculate the profitability of measures, it is necessary to determine the maximum damage that could be caused by a risk. In addition, it is calculated how likely the damage is that the damage will actually occur. Such an assessment is now available for the lower part of the Brienz slide between the village of Brienz/Brinzauls and the Albula river. It is called “Landslide Village”.
Buildings, roads, lines and land
The canton's risk analysis for landslides village looks at infrastructures and tangible assets of private individuals, companies and the municipality that could be damaged or destroyed by the landslide village. In total, these are worth around 177 million francs. These include buildings with an insurance value of just under 77 million francs, roads worth over 22 million, water and sewage pipes worth just under 9 million, high-voltage and data lines worth 10 million francs and the Albula line of the Rhaetian Railway worth 7 million francs.
The value of 14.5 million Swiss francs of building land and 19 million commercial land and movable objects in buildings worth 18 million francs are also included. “The calculation of the possible total damage is precisely specified by law,” says Christian Wilhelm, Head of Natural Hazards at the Grisons Office for Forest and Natural Hazards (AWN). “As with other calculations, we can only take into account the devaluation of building land to a limited extent in the case of Brienz/Brinzauls. It loses value if you are no longer allowed to build in the landslide area. Nevertheless, forest legislation only provides for minor compensation for this.”
“The Brienz slide is a major challenge for everyone affected. It asks the residents of Brienz/Brinzauls questions that are existential in the truest sense of the word,” says Mayor Daniel Albertin. “Together with the federal government and the canton, the municipality is doing everything it can to preserve Brienz/Brinzauls in the long term, as it has been their home for many families for generations. That is why we are examining and doing everything we can to save the village in the long term.” Nevertheless, the financial side of the restructuring measures must also be considered, emphasises the municipal president. “The municipality, but also the canton and the federal government can only provide funding for restructuring measures if they are effective and if the measures do not cost more than the potential damage they prevent.”
Analysis of the mountain landslide in progress
The risk calculation now available includes damage caused by landslides in the village. A second calculation for the “mountain landslide” is in progress. This is located above the village and poses risks due to slipping or falling rock masses that could damage the village of Brienz/Brinzauls or the districts of Vazerol, Surava or Tiefencastel.
However, the second calculation is much more complex, as Christian Wilhelm from AWN explains: “The damage caused by the village landslide is relatively easy to understand and estimate, as it is presented to us and those affected every day.” It is different with the mountain landslide. Here, the potential damage is calculated in computer simulations. Today, these can calculate fairly precisely to what extent, for example, a rock slide would cause damage if a certain volume of rock were to break off from a specific zone.
“But what we can only roughly predict is the question of where what will happen and what is the probability that it will happen at all,” says natural hazards expert Christian Wilhelm. In addition to the landslide itself, the risk analysis for the mountain landslide also includes Vazerol and parts of Surava and Tiefencastel, which could be damaged by rapid processes, such as a rock slide or subsequent processes, such as debris flows. It also looks at the costs that would arise as a result of service interruptions on railways, roads and supply lines.
The calculation of the mountain landslide is therefore very complex and will take some time. It will be completed in summer 2023 at the earliest.
This text was published in 38th information bulletin from the municipality of Albula/Alvra on Brienz Rutsch dated January 13, 2023 published. Christian Gartmann has been the information officer of the municipality of Albula/Alvra for Brienz Rutsch and a member of the municipal management staff since 2019.