54 The role of water for sustainable urban planning

Danijela Milosevic and Martina Winker, ISOE - Institute for Social-Ecological Research, Germany

Why water?

The city is dependent on water, because water plays an essential role for its development and functioning. The functions of water are diverse and cover not only domestic purposes and discharge of waste but also include ecological functions. These are linked to green space management, landscape design, crop cultivation and biodiversity. But also functions such as temperature buffering are becoming more important. Water thus forms a cross-sectional topic that integrates several areas such as climate protection, quality of life, resource and energy efficiency. These connections show the importance of water for an urban development.

Because urban planning and municipal water management have significant influence on water infrastructure, it is worth taking a closer look at the potential for sustainable development in terms of water management designs that lies here. This post mainly focusses on the discourses and the developments in the German context.

Water infrastructure for a sustainable urban development – an example

One way towards sustainable development is to close water and resource circuits at the city-level. This decreases the city’s water requirement from, and its influence on, the ecosystem and makes itself more independent and resilient. Technical intelligent solutions that serve this purpose are based on the separate collection of various wastewater streams, targeted and appropriate water treatment, the recirculation of water resources, and the recovery of nutrients and organic matter contained. The New Sanitation Systems (NASS) offer solutions to these principles. Many of these technologies focus on domestic wastewater, which plays a central role in urban areas. Due to its modular design and the choice of the degree of centrality, such solutions can be combined and implemented at the level of the bathroom, the house, the block, the neighborhood or even the whole city.

Fig. 1: Alternative wastewater infrastructure at neighborhood level: Rainwater is used to supply local waters, for irrigation or is infiltrated. Toilet wastewater (blackwater) is going to a biogas or composting plant instead of entering the mixed water disposal and domestic wastewater without toilet water (greywater) is treated and can be reused for toilet flushing or other domestic purposes while undergoing heat recovery. (modified from Winker, 2015)

An example of an innovative system solution that enables the transformation of the existing water infrastructure is shown in Figure 1. The separate collection of greywater (low contaminated wastewater produced during showering and hand washing or from the washing machine and in some cases from the kitchen sink) allows an uncomplicated treatment and heat recovery. After all, the average water temperature leaves the building at 22°C (Berliner NetzwerkE, 2011). The recovered heat is used to heat drinking water and to support heating spaces in the house. The treated greywater can then be used for toilet flushing, for the washing machine, to irrigate green spaces or to supply a nearby water body. The blackwater (wastewater from toilets) is transported with minimal water content through vacuum or excess pressure. Its organic material can generate energy by the means of a biogas plant or substrate for soil by a composting facility. As for the rainwater management, green roofs or retention basins (that are already frequently used) evaporate or seep the majority of the rainwater locally. All these possibilities show the huge design potentials: rainwater, purified greywater and blackwater can be used for green spaces and open watercourses, which in turn produce food (urban gardening, urban farming), create, maintain and expand recreational areas (parks), secure ecosystem services and protect against the effects of climate change (droughts, heat waves, floods, intense precipitation).

Innovative technologies must be accepted by the users in everyday life to be successful. Therefore, it is important to understand the users’ preferences, attitudes and needs and their handling of building services. It seems that users are open to such designs in pilot projects that implement such innovative technologies, mostly exist at building or block level. For example, residents in four apartment complexes, in each of which greywater treatment and heat recovery are implemented, drew the conclusion that the facilities were virtually not an issue in everyday life and that they were largely satisfied with their sustainable water system (Hefter et al., 2015). A major issue for them was the unobstrusive operation. The advantages reported were the resource savings while cost savings were considered as less important. However, the respondents differed noticeably in their open-mindedness and their interests towards the water techniques.

There are also some large-scale projects like the Jenfelder Au in Hamburg or the Flintenbreite in Lübeck, both in Germany, where innovative water infrastructure is implemented at district level. Other international examples are Sneek in the Netherlands or Semizentral in Qingdao, China.

Implementation: Significance for urban planning

Because of the significance of water for planning processes, the term ‘water sensitive urban design’ has evolved (Eisenberg et al., 2014). It enables the closing of water and resource circuits and the emergence of urban natural water balance. This is less of a restriction, but holds in contrary, as has been shown before, a tremendous creative potential. Urban planning should therefore take into account the role of water in all its different functions. Systemic and interlaced thinking that encompasses both natural resources (water, air, soil, and landscapes) and social dynamics is necessary to ensure integrated urban planning. It is important to consider environmental, social, and economic criteria. Thinking in terms of disciplines and the implementation of individual measures often lead to unwanted external effects. To enable sustainable urban development, an inter- and transdisciplinary collaboration is as important as the participatory user involvement in terms of the balance of different interests. We believe that solutions can therefore be found that satisfy the different needs and overcome conflicts of interest.

The opportunity for water transformation depends greatly on the dynamics of urban development and the transformation effort of the individual districts (Kluge & Libbe, 2010). Sustainable development is particularly promising where a high development dynamic hits a low transformation effort. Therefore the opportunity for water infrastructure transformation which strengthen the interconnections between the urban green and water bodies very much depends on the type of settlement structure in combination with its spatial location in the city. It is necessary on the part of the city to have a “future picture” in mind to pursue a directed transformation management and go beyond ‘random’ and small-scale changes at domestic or block level. It should be the responsibility of cities to create such a vision and steer the transformative process as administrators of the public commons.

Various sectors such as climate adaptation, demographic change, energy (production), green spaces, and food production all impact urban planning processes. Water as a cross-sectional issue offers the opportunity to connect and integrate urban sustainable development.

References

Berliner Netzwerk E: Gebäudebezogene Nutzung von Abwasserwärme. Berliner Energieagentur GmbH, Berlin, 2011

Eisenberg, B., Nemcova, E., Poblet, R., Stokman, A.: Lima Ecological Infrastructure Strategy. Integrated urban planning and design tools for a water-scarce city. Deutsche Gesellschaft für Technische Zusammenarbeit GTZ, Eschborn, 2014

Hefter, T., Birzle-Harder, B., Deffner, J.: Akzeptanz von Grauwasserbehandlung und Wärmerückgewinnung im Wohnungsbau. Ergebnisse einer qualitativen Bewohnerbefragung. netWORKS-Papers Nr. 27, Berlin, 2015

Kluge, T., Libbe, J.: Transformationsmanagement für eine nachhaltige Wasserwirtschaft. Handreichung zur Realisierung neuartiger Infrastrukturlösungen im Bereich Wasser und Abwasser. Deutsches Institut für Urbanistik, Berlin, 2010

Winker, M.: netWORKS 3: net @ works, Intelligente wasserwirtschaftliche Systemlösungen in Frankfurt am Main und Hamburg. INIS-Statuskonferenz, Hamburg, 21.-22.01.2015

Author Biographies

Danijela Milosevic is research assistant at the Institute for Social-Ecological Research in Frankfurt am Main, Germany, where she works in the research unit Water Infrastructure and Risk Analyses. There she deals with the possibilities of the transformation of conventional wastewater systems towards more sustainability. She studied Nutritional Sciences (B. Sc.) and Environmental Management (M. Sc.) at Justus-Liebig-Universität, Gießen with the focal points nutrition ecology, waste management and sustainable sanitation. Moreover, she is active as a journalist.

Contact email: danijela.milosevic@gmx.de

Martina Winker is research scientist at ISOE and head of the research unit Water Infrastructure and Risk Analyses. She studied agricultural sciences with the focal points agricultural engineering and ecology in Germany and Norway. In 2009 she received her doctorate by the Hamburg University of Technology for a thesis dealing with “Pharmaceutical residues in urine and the potential risks related to usage as fertiliser in agriculture”. Afterwards she worked for the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH in the area of sustainable sanitation.

Contact email: winker@isoe.de   

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