In the Senne valley, we are creating around ten natural retention water areas. All of these areas could store a total of more than 350,000 m³ of water to limit flooding in the basin. In addition to this objective, facilities are created in each of the zones, in order to preserve, protect and increase biodiversity. The improvement of hydromorphology as well as ecosystem services is also taken into account in each of the zones. Ecosystem services represent the benefits that humans derive from ecosystems without having to act to obtain them.