Wednesday, 21 October 2020
Central Europe Programme

Urban Water Footprint: a new approach for water management in urban areas

What we have done

WP5 Activities

Building on the results of earlier work packages, WP5 aims to improve the water footprint of the municipalities of the three Water Footprint Labs. The first steps have already been taken. A survey instrument was developed in order to collect information from the three case study municipalities on their local water management problems and measures that can be deployed to address these problems. The survey instrument was distributed among project participants and clarifications on the data to be collected were made. The Water footprint labs, in cooperation with their local partners, filled in the survey after which a best practice report was developed based on the three surveys and a review of local water management literature.

The survey identified that the key challenges faced by the three municipalities are - to various degrees - continued urbanisation and soil sealing, climate change, temporarily insufficient water resources (e.g. during an arid summer), limited storm water management capacity, leakage of the drinking water network, pollution of the water resource that serves as a source of drinking water and pollution of water bodies.

Goals can be set to address the above listed problems. The following table describes a variety of goals as well as the measures that can be used to achieve them. The best practice report provides details on all of these measures, as well as practical cases and illustrations from the municipalities of the Central Europe region.

GoalTool/Measure


Saving drinking waterSetting water and wastewater tariffs at cost recovering levels
Metering of consumption
Supporting the penetration of water saving technologies
Education of citizens, students
Reducing leakage
Rainwater harvesting
Changes to the building code


Improved storm water managementLess soil sealing
Green roofs
Rainwater harvesting
Separation of storm water collection and the sewer
Rehabilitation of the existing sewer
Changing the building code and other technical guidelines


Mitigation of climate change related heat wavesGreen roofs
Reducing soil sealing


Lower effluent dischargeExtended collection of wastewater
Separation of storm water collection and the sewer
Improved wastewater management
Constructed wetlands


Lower risk of ground water pollutionExtension of the sewer
Rehabilitation of the existing sewer


Reducing the virtual water footprintEducation of citizens, students


Improved retention of precipitationReduced soil sealing
Green roofs
Rainwater harvesting
Changing the building code


The picture below illustrates one of the soil sealing reducing measures from the city of Wroclaw. Instead of a continuous asphalt surface, in this parking lot grid paving is applied, so that rainwater can ooze into the soil, both improving the water balance of the soil and releaving the pressure on the storm water collection system of the city.

As shown in the table above, most urban water management goals can be achieved through a number of different measures, and vice versa, most measures contribute to more than just one goal. Therefore when devising improvement plans for the UWFLs there is indeed a choice. Moreover, many of the measures deliver benefits outside the narrower realm of water management, improving the micro-climate, enhancing local ecology, creating recreational areas etc. The measures have different implications in terms of costs, feasibility and ease of implementation as well. In short, a careful assessment of the measures is needed before the most optimal ones can be selected for the improvement plans.

Furthermore, some of the best practices are universally applicable, while others are site specific. Green roofs, for instance, under the Central European climate always contribute to storm water management, while the feasibility of constructed wetlands for the purpose of cleaning wastewater streams is rather site specific, depending e.g. on the available space as well as the pollution content of the water.

Having interacted with the public, one of the conclusions from Innsbruck is that the public seems to be more interested in awareness building measures then the actual water footprint models. On the other hand, for professional planning purposes models do serve their purpose.
Another lesson for the future is the time scale of the best practice measures. Most of the measures require a long time horizon of years and even decades. This on the one hand fits well with the timeframe of urban planning, and on the other hand the impact of some of the external factors (e.g. climate change) will also be apparent.

A distinction needs to be made between easy to develop, low cost measures and expensive investments requiring careful design. An example for the former is soil sealing, turning formerly sealed unused asphalt areas into green areas is not very costly and brings almost instant benefits, although, as the example from Innsbruck shows, even such a measure may be slow to implement. An example for expensive investments may be taken from Wroclaw, where the upgrade of the wastewater treatment plant took years of preparation and construction and required both external funding and the raise of service charges. The same applies to the extension of the sewer, constructed wetlands, or reduction of water losses from the drinking water network.
The next step under WP5 of the project is identification of improvement objectives and the development of water footprint improvement plans and carrying out the first steps towards this improvement. We will cover these developments in the next issue of the project newsletter.
WP5_photo

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