How to use rainwater to create climate resilient urban spaces? [Webinar highlights]
In a webinar on November 12th, Field Factors and Delft University of Technology elaborated on the main principles of designing circular water systems in urban areas, using natural treatment systems and the subsoil.
Participants got to learn the ins and outs about the technical guidelines for the implementation of these circular water systems.
Through three presentations, it was discussed how you can create climate resilient urban spaces through smart re-use of rainwater, and more specifically: how this can integrated in a spatial design; how the right water quality can be reached; and how underground storage can be used for storing large volumes of water on a minimal footprint.
The first presentation was held by Karina Peña, CEO of Field Factors who rose the questions: How to design a nature-based solution to manage rain? And how can you integrate circular water management in order to cope with the two climate extremes: having to deal with too much water on the one hand, while also being faced with intense droughts in summer months.
She explained how Field Factors aims to redesign our cities by restoring water locally, in a decentralised grid of circular water systems. A clear contrast to the traditional approach of discharging stormwater via the centralised linear system. She explains the five steps in which this circular system can be implemented: 1) collection of the runoff; 2) temporary retention; 3) treatment with a biofilter; 4) storage; 5) local use. Such circular water systems can basically be implemented everywhere, as long as you design for the specific spatial, water quality and geohydrological conditions. Karina presented three main guidelines for designing a circular water management system. First of all, you will need to implement some measures to change the direction of the flow and the importance of considering vertical flows in that configuration as well. Secondly, you will have to balance the water offer and demand, which are dependent on several parameters that were explained in more detail using the reference project at the Sparta Stadium in Rotterdam. Thirdly, it is desirable to integrate water in the spatial program, depending on the available surface area and characteristics of the location.
The five steps of a nature based circular water system
Joshua Gallegos of Delft University of Technology specialises on the performance of natural treatment systems. In his presentation he talked about water quality, explaining typical pollutants in urban runoff and how water treatment systems can be designed. The main question of his presentation is: How to treat stormwater with nature-based solutions?
The first remarkable point of the presentation is that the human overall perception of what clean water is, is a bit unclear. After the most common stormwater pollutants were mentioned, it was explained how drainage systems work and how the stormwater runoff gets polluted along the way. After that, Joshua introduced the concept of Sustainable Drainage Systems, and explained why these are effective in retention and infiltration; controlling pollutants by capturing near sources; and reducing peak stormwater flows. Finally, Joshua summarized how stormwater could be treated using nature based solutions, such as going upstream in the drainage network; integrating multiple barriers; buffering rain events; maintaining the conditions for pollutant attenuation; and designing within the treatment limits of the system and the specific use of the water. According to Joshua it is important to take into consideration that even though you may not be able to drink the water, the potential (non-consumable) applications of good quality fresh-water are endless and replacing the use of tap water with a circular rainwater system can make a real impact.
Boris van Breukelen of the Delft University of Technology handles the question what the benefits are of different types of Managed Aquifer Recharge. He specifically zoomed in on Aquifer Storage and Recovery (ASR) technology and how this can be implemented in urban settings.
The main benefit of using MAR to store urban runoff in the subsurface, is its capacity to store large volumes of water on a minimal footprint. Since space is at a premium in dense urban areas, there is not enough room to store water at surface level. MAR can provide a seasonal buffer of fresh water, which is locally available, right beneath our feet. In this presentation the specific conditions of the Netherlands were highlighted, before Boris went on to the benefits of designing ASR systems using multiple infiltration/abstraction wells. The implemented ASR systems in Rotterdam and The Hague were used to further explain the functioning of such systems. Boris also zoomed in on the requirements for infiltration water quality and the effect of pre-treatment on preventing well clogging. Also, the potential of ASR to remove pathogens from the water is important to ensure save water re-use. Boris advised attendees to optimise the residence time of the infiltrated water in the aquifer through a smart AS(T)R design when creating seasonal buffers from rainwater.
From a linear system to a circular urban water system
Field Factors hopes to have inspired the many attendees from all over the world to break with traditional linear water system design. Having learned the main principles of designing decentralised circular water systems, we hope to see many more cities make use of rainwater to create green, cool and climate resilient urban spaces.
This webinar was held as part of the EIT Climate-KIC Bluebloqs Circular Water System project.
In the upcoming months, our Climate KIC partners wil host a series of webinars about this topic.
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