Project by: Karim van Wonderen (Netherlands) & Sofia Molpheta (Greece)
Location: Province of Zeeland, NL
Client: Wageningen University MSc thesis
Landscape Infrastructure for food sufficiency under salinizing conditions
Saline Landscapes proposes an landscape-based infrastructure for the production of saline aquaculture crops that simultaneously includes recreational, nature- and coastal defence purposes. The design focuses on the Zeeuwse Tong pilot farm (Z.T.), an innovative farm for integrated multi-trophic aquaculture, based in the Dutch province of Zeeland. This state-of-the-art aquaculture farm is set up to produce fish, mussels and saline crops in a closed cycle of nutrients and waste, and—contrary to the present day farms—does not demand fresh water intake, but functions best in a saline milieu. The designers took up the challenge to convert the innovations of this individual, 4 hectare, bio-industrial scaled farm into a 600 hectare, multi-purpose aquaculture infrastructure that applies the Z.T. principle on a landscape scale.
The proposed site is situated on the island of Noord-Beveland in the province of Zeeland, a reclaimed area known for its long water-related history and its productive agricultural grounds. Local economy depends on coastal recreation, concentrated in the western dune coastlines and fresh water dependent farming practices in the hinterlands. The present crop farming practices demand regularly flushing the water system with fresh water in order to artificially sustain a marginal fresh water lens; a practice that will become untenable in the future due to increasing saline ground water seepage and decreasing fresh water supplies. Because of this, a more sustainable approach is proposed: adapting to the given conditions by gradually converting to a salt-based agriculture and aquaculture while maintaining or even increasing productivity and profit, simultaneously with an expansion of hinterland recreation and nature development by embracing historical features and landscape scenery. This seems to comply with the demands for a better spread recreational program and hinterland development for the purpose of nature and leisure.
How it works
At the start, a cooperation of multiple farms is proposed; the collaboration of farmers will results in lower costs due to a combined water system, nutrient system and filtration system, and therefore higher profits. In order to design this saline landscape infrastructure, the Z.T. unit was broken down into individual components, which where then upscaled, adapted and then reconstituted, so as to allow for public interaction, nature development and contextual application. Then, two design enlargements where made.
In the first enlargement, a large-scale, shared saline water system is introduced. Sea water is pumped into small retention lakes and from here on flushes through the aquaculture fish ponds (inner set of inlagen), taking away nutrient-rich waste water that is then used in the saline productive lakes, where cockles, mussels, ragworms and algae clean the water before it enters either the saline crop fields (adjacent inlands) or the saline nature area (outer set of inlagen) and is at last returned back to the sea or recycled into the pond system.
The aquaculture system adapts to local circumstances by introducing a new double row of ‘inlagen’. Inlagen, a type of double dike system where an inner dike was added as the outer one became weak, are a part of the cultural heritage of Noord-Beveland and where used for coastal safety and buffering salt intrusion. The same principle is adapted to a triple dike system, thus becoming the basis of compartmenting the water system as well as adding to coastal safety. Also, they form the basis for an extended recreational network with bicycle paths and viewpoints. These new inlagen are bordered by the new saline agricultural fields, which in turn are surrounded by a water buffering ring ditch that closes the saline regime. Existing farms are transformed and surrounded by small ring dikes, while a food processing area is located near the local port, hereby connecting to land- and water transport. Overall, the site is now producing several food products with minimum input and maximum usage of nutrients, provides for increased coastal safety, adds recreational, educational and experiential values, incorporates new saline habitats that increase local biodiversity, and relates to historic landscape features and local context.
The second enlargement further extends the idea of using natural conditions for saline farming, while nature and coastal defence functions are more emphasized. The location of the site is directly opposing the mouth of the Scheldt river and takes the compulsory nature compensation (also referred to by The Broad Coast) as a point-of-departure. A system is created that is more open to natural dynamics and tidal flux and that is less regulated than the former. The primary dike is backed up by a secondary and tertiary dike ring. Aquaculture ponds are placed between the double dike ring, the primary and secondary are then perforated in order to install tidal flux and dynamics. Sea water can now flow into the system due to tidal influx. It will enter the primary dike, advance through the secondary dike, where it will overtop into the aquaculture ponds which can be used as fish beds. With low tides, nutrient-rich water will be discharged from these ponds and move through the productive pockets, here getting filtered by mussels, cockles, etc., before running into the saline nature filters and flowing back into the sea. Within the fluctuating area between primary and secondary dike, different types of floating fishponds can also be placed, benefiting from the tidal influences. The abundance of potentially harvestable saline vegetation (nature filters) within this area contributes to the nutrient absorption, creating a system almost as efficient as the initial industrial scale model, but now open to its environmental context.
Due to the combination of saline nature and profitable aquaculture, it is believed that both the demands of the Schelde treaty and of the local farmers society unwilling to give up profitable agricultural land for sole ‘unprofitable’ nature compensation can be met, hereby presenting one of the first plausible solutions after years of debates and Parliamentary commissions failing to address the problem. Besides this, a saline landscape will evolve with sublime delta experiences that will entice tourists, bird watchers and nature lovers, as well as improve coastal safety, water quality and habitat diversity.