Our teams on call in the event of flooding

As things stand, most hydroelectric schemes in Switzerland indirectly play a protective role against natural hazards. Floodwater laden with sediment and flotsam is not allowed to pass through a turbine. Instead, water collection is stopped and water discharged only once retention capacity has been reached. Preventing sediment-laden water from reaching the turbine limits the build-up of silt and negative impacts on plant (wear and tear, etc.). In this respect, water intakes and discharges from hydroelectric power stations are - like bridges and other structures along watercourses - structures that need to be monitored and protected against flooding.

Avoiding logjams

Operations teams are the first to be called out in the event of flooding. They are put on alert as soon as an incident is announced with the aim of preventing hydroelectric facilities from contributing to the violence of the floodwaters. Logjams are the phenomenon most feared. Operations teams also take steps to protect the facilities and prepare for their rapid return to production once the floodwaters have subsided.

Working with municipalities and the canton

If a structure's stability and integrity are threatened, the Civil Engineering & Geodesy unit is summoned to support the operations teams. Scouring, boulder impacts and rising water levels can exacerbate hazards downstream.

Most at risk of these phenomena are dikes and dams, with their mass of water behind them. Interventions involve assessing the seriousness of the incidents, taking steps to reduce the threat and, if necessary, alerting the authorities and blue light services. Storage facilities such as these are subject to emergency regulations under the authority of both the Confederation and the cantons. The regulations define the protective measures to be taken and the organisation and communication to be set up with experts inside and outside HYDRO, including the emergency response teams of the municipalities and/or cantons.

Finally, once the flooding has subsided, the workload for the operational teams can be considerable, as they have to clear the flotsam trapped in the structures.

Feedback and improvements

Events leading to prolonged shutdowns or damage are always analysed in collaboration with the engineering units. This allows us to plan the restoration of facilities and, with an eye on natural hazards, improve the reliability of hydroelectric production and the level of safety. To facilitate this, HYDRO gathers watercourse-related observations and feedback at all operational levels and over a wide area.