Hydropower is an essential part of the energy mix in France, accounting for around 20% of installed capacity. Climate change is projected to increase the frequency and intensity of extreme precipitation events and to accelerate snowmelt, which would result in increased flood risk. Flooding can adversely affect dams causing overtopping, outages, damage to equipment and adverse downstream impacts. It is essential that dam operators take these risks into consideration and implement adaptation measures as needed.
The Hydro Engineering Centre (CIH) at Electricité de France (EDF) developed the Piano Key Weir (PKW) system. The PKW system is an improved flood discharge system that helps to release water safely from dams during heavy precipitation events. The increased “crenelated” surface area of the PKW system provides an additional spillway to manage increased water flow. This is particularly relevant in the narrow gorges present in some of the alpine regions where PKWs have been installed.
There are now 10 dams in France equipped with PKW technology and around 30 globally. The Malarce dam discussed in this case study was the 6th dam in France to be equipped with PKW technology for the purposes of improving water flow management. It is located on the Chassezac River in Ardèche in southern France.