Healthy beach and dune systems are one of the best solutions to protect the shoreline. When the sand level is insufficient, or when the dune and/or the beach are urbanised, sediment flows essential for adaptation are no longer possible. The drainage system allows the beach – particularly at the top – to reconstitute a sufficient sand stock serving as a buffer during storms.
The system consists of several drains positioned underneath the beach, parallel to the coastline, and connected to a pumping station whose action creates a dry zone facilitating the infiltration of waves and the deposition of suspended sediments. At the same time, part of the wave energy is absorbed while the erosive effect is attenuated. Dryer sand facilitates sediments’ wind transport, which supports beach accretion. In addition to mitigating erosion, this system allows the exploitation of highly filtered seawater to supply the Aquabaule aquatic centre (basins and heat pumps) and thus save energy. On the La Baule site, the objective of this action is twofold. It is both to limit erosion and to supply the Aquabaule aquatic centre with highly filtered sea water, both for the pools and their heat pump.