Transformation towards circularity in the construction of urban water systems.

The hydrological cycle crosses three environments: the geosphere, the biosphere, and the technosphere. The geosphere is the collective name for lithosphere, hydrosphere and atmosphere. The technosphere is the part of an environment composed of a wide variety of technological artefacts and the biosphere is composed of all ecosystems.

These spheres cannot be analysed and described separately but need to be understood as one hybrid space. Hybridity is defined as a system that is composed of several separated systems (#REF). Not only the spheres are hybrid, but also the separated spheres, like the hydrosphere, or the hydrological cycle in urban areas consists of two systems, the natural water system and the water chain, are intertwined in a new hybrid system. In order to be able to intervene in this system, it needs to be described and analysed to be understood. Moreover, it needs to be linked to urban space and quality to be able to harmonize urban development and water management.

The urgency at the core of this study is the contemporary issue of climate change and consequently the changing hydrological cycle. To deal with pluvial flooding in cities, reduce energy use by introducing decentralized sewer systems, improve water quality by separated sewer systems and introducing blue-green infrastructure this study aims to give proper understanding and means to improve the water system, the water chain and urban quality simultaneously.

One of the measures to deal with water excess and energy use reduction is the application of a decentralized water circulation system called “Closed City”, which was presented in 2005. Closed City is defined as “a city that does not have adverse effects on its surroundings, such as water depletion or emission of pollution”. This approach is aiming to improve the water storage and water purification capacity of cities, to store and recycle rainwater and sewage. This is believed possible by creating a self-sustaining water circulation system that responds to water shortages and floods.

When applying these new water cycles to urban areas, it is important to evaluate the applicability and performance of Closed City in the urban hybrid system.

The study area is Zevenkamp in Rotterdam, the Netherlands. In Rotterdam, the municipality and the Water Board use “Waterplan 2 Rotterdam” to promote projects on water storage, water quality, protection from water, with the main aim to realize a waterproof city. Especially the fact that in Zevenkamp, which was developed in the 1970s, is awaiting urban renewal to deal with renovation and social and economic issues, makes it a good case to investigate how a new water system which aims at reaching the Closed City concept as close as possible.

Besides the goal to represent the new water flow and its effect in urban typology in general, the added value of this research is the representation of responsibilities of public and private stakeholders and the explanation of ‘purpose’ as the new P in the triple bottom line in which prosperity is not monetary but in which the new value system has integrated meaning.

The main question tackled in the research is: which synergies can be found when the design of new urban systems including the scale of the household is based in circular water flows? The aim is to find the intermediate scale between bottom-up and top-down.

In the project, the method of “hybridity as interdisciplinary design” is tested and the expected result is understanding of how water flows in the specific location can inform the design.