**3. Floating potential for urban embedded food production. A zero-land footprint strategy**

In recent decades, we have witnessed two related trends: land occupation on the one hand, and soil sealing on the other, both of which are the result of city growth and expansion of urban areas characterized by high building density ratios. Due to scarcity of available empty land within cities, agri-food production systems often play a marginal role in temporal (transient), spatial (interstitial), social (e.g., women and low-income groups), and economic (e.g., financial crisis, food shortage) terms. Indeed, urban farming and food production in cities are currently limited to the transformation of brownfields, residuals, and urban voids into micro-farming, private rooftop cultivation, urban community and institutional gardens, small-scale urban farming, urban aquaculture and aquaponics, urban forestry, and hydroponic and aeroponic vertical farming systems. In response to scarcity of land and/or water

resources, the spread of vertical farming in cities has grown significantly, allowing for the combination of housing and farming within a single building inside the city.

Recently, a zero-land-footprint strategy that takes advantage of the continental and tidal hydrographic network for food production has gained popularity. This strategy entails the use of floating structures along rivers, lakes, or coastlines to house greenhouses and farms within urban centers.

Water proximity has always been a crucial component in the establishment and development of human settlements [30]. Many cities were built up along coastlines or at the mouths of large rivers because they served as collection points for raw materials coming from the inner areas, they were supplied by an efficient water transportation network and were guaranteed with access to clean water. Cities lacking permeable and underused soil but located near rivers, lakes, or coasts could easily host water-based food production facilities. The hydrographic network or the sea itself provides a huge potential for the floating development of food producing facilities in cities characterized by high building density. More precisely, floating farming facilities can provide several environmental and sustainability advantages [31], including: reducing the burden on freshwater by using seawater desalination techniques or collecting and storing rainwater; introducing new cultivable or breeding surfaces where permeable land and freshwater are scarce, particularly in high density urban areas; providing complete and self-sufficient farming systems in terms of automated planting, harvesting, processing, and export, drastically reducing transport costs; and providing the possibility of relocation in more appropriate sites when a given location is no longer suitable for any reason (environmental or pollution risks, political conflicts, and urban population shifts). Furthermore, floating greenhouses or breeding farms could be designed as multilevel vertical systems to increase overall farming surface and yield, ensuring the economic viability of the floating farm concept.

Floating agriculture is actually a vernacular soilless practice widely spread over Southeast Asia (Lake Inle Kay La floating village with farming and fishing arrangements), Middle East (Al-Tahla floating Islands in the southern wetlands of Iraq), and South America (Totora reed floating islands in Lake Titikaka, Peru). Different low-tech systems have been used for thousands of years and have allowed farmers to grow crops in flood-prone areas, wetlands, or lakes, where no other land use was conceivable. These systems usually consist of plants on rafts made of composted water weeds piled up on water bodies, by simply stripping nutrients released from decomposing organic material [32]. These systems are now seen as a strategy to cope with the combined effects of urbanization, land consumption, cementification, and climate change in areas that are more vulnerable to sea-level rise and coastal erosion, where flooding prevents land from being used for agriculture for extended periods of time [33] or where there is no available land for agri-production.

Floating Farm 2.0, designed and built by Goldsmith Studio, is the world's first floating dairy farm, located in the port of Rotterdam. The Floating Farm Dairy is a compact and efficiently stacked urban farm with a strong public and educational character. The building combines technical installations, storage, production, and processing of dairy on board. The farm produces fresh dairy products from its 40 cows. All raw dairy products are processed on-site and delivered across the city as fresh milk and yogurt. Floating Farm 2.0 is designed according to a circularity concept to employ leftover goods produced by the city, such as grass from public parks and food waste, to feed animals and return fresh milk to the city. This circular approach not only finds a new effective use for leftover products, but it also reduces food transportation costs and pollution by keeping food production and consumption
