The Role of Rain and Storm Water Management in Water Sensitive Urban Planning

Report from the virtual closing event for the Connective Cities learning process on 27 November 2023

Graphic: Florence Dailleux

Strategies for climate change adaptation: rain and storm water management

Municipalities around the world must prepare for extreme weather events in the face of global warming. These events include storms and heavy rainfall, which can cause large amounts of rain to drain off within a short time, resulting in rising river levels. The disaster in the Ahr Valley in Rhineland-Palatinate in July 2021 showed that communities must also be prepared for extreme weather events in Germany. In other parts of the world, massive seasonal rainfall and flooding have long been part of reality, but are being exacerbated by climate change. How can cities mitigate the risks for their population and infrastructure and respond quickly in an emergency? Connective Cities facilitated a practice-orientated exchange of experience on this issue. The aim of the learning process was to connect municipal experts from Germany and other world regions, promote the exchange of expertise and encourage the development of new solutions.

Learning process kicked-off with a dialogue event in Cologne in 2022

In December 2022, Connective Cities and StEB Köln (City Drainage Services Cologne) in cooperation with United Cities and Local Governments (UCLG) organised an international dialogue event on managing storm and heavy rainwater in the City of Cologne, Germany. 41 experts from 16 cities and eight countries took part in the meeting. The participants presented ongoing projects from their respective municipalities, took the opportunity to engage in peer-to-peer consultation, exchanged ideas on how to reduce the risks of heavy rain and storm water events for residents and municipal infrastructure and discussed new project ideas. The dialogue event was the start of a year-long learning process. The aim was to further advance the topic of water-sensitive urban planning by taking advantage of the ideas and new contacts from the kick-off event.

Wrap-up of the Connective Cities learning process

One year after the successful kick-off meeting, the learning process ended on 27 November 2023 with a virtual closing event. 12 participants met once again to report on their experiences and activities. The agenda included the following questions: 

  1. Did the dialogue event and the learning process impact ongoing activities in the municipality or municipal company? Did it stimulate change?
  2. Have contacts from the network been used for professional exchange?
  3. Were there any project ideas that were pursued and elaborated? Have there been any subsequent meetings or expert missions?

Andreas Wolter, Mayor of the City of Cologne, addressed some opening words to the municipal experts. He underlined the urgency and importance of the topic and referred to the international climate conference COP28, which was scheduled to start in Dubai on 30 November 2023. He called for politicians and administrations to collaborate closely and find solutions together – also in development cooperation projects.

Based on the guiding questions, the participants exchanged their expectations of the meeting and their findings from the learning process in two five-minute break-out sessions. Afterwards, the representatives from Cologne, Zarqa (Jordan), Düsseldorf, Mannheim, Heidelberg and Banjul (The Gambia) shared their learnings with the other participants. 

Reports from Cologne, Zarqa and Düsseldorf

Cologne: Dr Martin Cassel and Maria Ceylan reported that StEB Köln had benefited from a contact with a fellow from the Istanbul Policy Center-Sabanci University-Stiftung Mercator Initiative during the dialogue event in order to initiate an exchange on the topic of integrated water research. During the first expert mission to Istanbul, a delegation from StEB Cologne was given the opportunity to present its sponge city concept, among other topics, at a round table on the topic of water-conscious cities in Istanbul in April 2023. A group of experts from Istanbul visited Cologne in August 2023 for a further exchange of expertise.
Furthermore, Dr Martin Cassel also took part as an expert in the "Flood Management for Risk Informed Urban Development" learning process conducted by Connective Cities and the Global Initiative on Disaster Risk Management. He attended a meeting in Windhoek in April 2023 and participated in another session in eThekwini in November 2023. Mr Cassel was able to initiate valuable contacts for future exchanges.
Several projects on the topic of water and climate impact adaptation are currently being worked on within the StEB Cologne. One of these is a digital rain compass to raise citizens' awareness of the topic and to warn them in case of an emergency. Dr Martin Cassel emphasised that Cologne is one of the leading cities in Germany when it comes to heavy rain and flood prevention. He is very keen to share knowledge and make it accessible to other municipalities.

Zarqa: Mohammad Alzawahreh from the Jordanian City of Zarqa was able to gain important impulses from the dialogue event in Cologne. He particularly benefited from the peer-to-peer consultations and learnt about some non-conventional approaches that do not require a high degree of engineering expertise. As a representative of civil society with good contacts to the city administration, he was able to encourage further training on the topic of rain and storm water management. The City of Zarqa is currently working on creating GIS-based water and rain maps. One important concern is to reach out to and involve the citizens - for example in flood prevention, but also in the responsible use of drinking and rainwater.

"I have gained two important insights from the event in Cologne: Peer-to-peer consultation methodology is a very fruitful approach and it's worth thinking about non-conventional solutions as natural based solutions rather than using engineering solutions."
Mohammad Alzawahreh, Zarqa, Jordan.

Düsseldorf: The Department for Urban Planning in Düsseldorf is currently developing the urban neighbourhood project "METRO Campus" together with a leading investor. A special focus is on sustainable water management covering the entire area. Marie-Luise Colditz from the City of Düsseldorf had already presented the project at the dialogue event. In May 2023, a series of cross-departmental workshops on dealing with heavy rainfall events addressed the employees of various administrative departments that are involved in the development process. Additional meetings were organised in collaboration with the transport planning/urban drainage and open space planning/urban drainage units. It was possible to agree on common goals for dealing with rainwater. 

As in Banjul (The Gambia), the topic of the sponge city is also high on the agenda in Mannheim. The municipality is currently conducting a model study together with the Technical University of Darmstadt. In Heidelberg, the fire brigade was trained on the subject of heavy rainfall. Both Heidelberg and Banjul see the need to better educate the population on how to deal with heavy rain and flooding.

UCLG Peer Learning Note

Claudia Ribosa from United Cities and Local Governments (UCLG) presented a peer learning note that was published after the dialogue event in Cologne and that  that summarises the event's content and methodology. It contains all the municipal examples, recaps the most important learning moments from the meeting and outlines the key recommendations drawn up by the participants in 2022. These include: 

  1. Inclusion of nature-based solutions as an alternative or supplement to conventional  (grey) infrastructure approaches
  2. Mechanisms for multi-actor coordination, including the involvement of communities, in flood management
  3. Improvement of information sharing systems
  4. Review of insurance and mitigation financing systems for local and regional governments
  5. Inclusion of risk assessments in urban planning

UCLG (2023): Pear Learning Note #33: Water Sensitive Urban Planning in times of Climate Change


Staying in touch and sharing expertise

To conclude the event, the focus turned to the possibilities for future collaboration. Sina Webber from Connective Cities offered to provide ongoing support from the network: Further meetings or expert missions can be organised on request, as well as the facilitation of expertise from the Connective Cities network or the publication of best practice examples on the website.

Participants then posted their requests or offers for cooperation on an interactive Miro board.

Expertise is requested on the following issues:

  • How can effective rainwater management be established at an early planning stage?
  • How can politicians be convinced to prioritise the issue of heavy rainfall prevention and management and to take action?
  • How can the infrastructure in existing areas of the city be transformed into a climate-adapted one? How can this process be organised across different departments?
  • How can the issue of rain and storm water management be strategically addressed in Zarqa, for example by support of an expert mission?

Expertise is offered on the following topics:

  • Protection measures and information of the citizens in case of heavy rainfall events
  • Implementation of rainwater management in the planning of new projects
  • Public participation processes in flood risk management
  • Risk management and risk mapping
  • Heavy rainfall forecasting and detection using intelligent measurement technology in topographically exposed areas
  • Modelling of flood events - feasibility studies on prevention measures

More information:
Review of the dialogue event "Water sensitive urban planning – how can heavy rain and storm water be better managed?", Cologne, December 2022. 

Julia Krakau in cooperation with Burkhard Vielhaber