Holzer Permaculture Solutions conceived and realized a retention system project developed for the La Plume estate in La Penne, a small village in the French region of Provence-Alpes-Côte d’Azur.
The aim of the project can be defined as follows: to revitalize and recultivate an old cultural landscape.
A comprehensive water retention system is a prerequisite for the cultivation of field vegetables and herbs, fruit-growing, agroforestry, and tourist use.
In practice, the conceptual design of Josef Holzer and Oliver Krische covers four ponds that are supplied with water from different catchment areas. The water landscape will represent an important substructure for the local food supply in the future. At the same time, it constitutes an ecological landscape element that is highly beneficial for the fauna and flora around the estate at both local and regional level. This concept enables a sustainable and comprehensive upgrading – both functionally and aesthetically – of the whole landscape with comparatively low effort.
Particularly in southern countries, climate change already entails dramatic consequences. Extreme drought is more and more often followed by flooding. In Mediterranean and subtropical climate areas, rainfall is very unevenly distributed throughout the year. Heavy rains occur in short bursts in fall or spring, whereas the summers are extremely dry and hot. As much rainfall as possible needs to be retained during these brief periods of heavy rains in order to reduce the adverse impact of dry periods.
The most important factor is water retention within the soil. Soils rich in humus have the capacity to store water in quantities up to fivefold their own weight. Humus formation, structural soil improvements, root penetration, and water-retaining contour farming are all measures that serve to improve the rate of infiltration and minimize surface water drainage, which can lead to erosion.
Ideally, the differently designed water retention facilities are interlinked in such a way that the water can be distributed across the landscape in a cascade-like way through gravity. On its journey from one pond to the next, the water is led over stones and gravel in order to raise the oxygen content and clean the water before reaching the following station.
In In permaculture, these complex and communicating water retention systems are used in gentle and quite diverse ways. They enhance biodiversity, have a positive effect on the microclimate, serve as a water storage facility for irrigation and can potentially function as water gardens or be used for aquaculture (fish, crayfish, ducks, etc.).