Water intake adapted to climate change
Retreat of the Tsidjiore Nouve glacier (Arolla), erosion, increased drift: the eponymous water intake has been revised to cope with the new climatic conditions.
The Tsidjiore Nouve water intake is located in the Hérens valley at an altitude of 2100 metres. It collects water from the eponymous glacier, which is then conveyed to the Arolla plant, where it is pumped into the main collector before flowing by gravity into the Grande Dixence dam.
In view of the retreat of the glacier and the increase in drift during storms, it was necessary to adapt the water intake. HYDRO, which is responsible for operating the entire Grande Dixence scheme, undertook this work in autumn 2023 in particularly difficult weather conditions. Two aspects were addressed: firstly, replacement of the degraveller valve, and secondly, modernisation of the command and control system.
Larger drain valve, sensor and monitoring camera
To enable the discharge of higher flows in the event of flooding, the drain valve on the degraveller was replaced by a model with a larger aperture. The geometric changes made to the structure required major sawing and concreting work to enable the installation of the new valve and its armouring, which were pre-welded in the workshop. The teams took advantage of this opportunity to repair damage to the concrete structure caused by freeze-thaw and boulder impacts. These major works were completed before the end of the year, since when water has again been flowing into the reservoir.
A second phase will find us renewing the command and control system. A probe and a monitoring camera will also be installed at the intake, enabling HYDRO staff in the Hérens valley to anticipate problems more effectively and intervene more quickly. The new control room will house a state-of-the-art processor and equipment.
In April, before the start of the pumping season, the operations team will check that all the equipment is working properly and commission it.
