The ongoing climate change is altering the water balance in our cities. Too much or too little water can lead to major damage. Extreme weather events such as heavy rainfall and periods of heat and drought will affect our lives now and in the future.
Sustainable, near-natural handling of rainwater is crucial for a liveable and resilient city of the future. Bonn therefore wants to develop into a water-sensitive city based on the principle of the sponge city!
The natural water cycle is to be strengthened by no longer draining rainwater into the sewage system as quickly as possible, but (temporarily) storing it, evaporating it or allowing it to seep away. This offers ecological and economic advantages. The soil water balance is strengthened with positive effects on plant growth and the urban climate. In addition, runoff peaks can be curbed as a contribution to flood prevention.
The path to the blue-green sponge city
The transformation to a sponge city requires the cooperation of various stakeholders at different levels, a variety of measures, financial resources and time.
The city of Bonn has embarked on this journey and developed a sponge city concept specific to Bonn, which was adopted in April 2024. In terms of content, a strategic target image and a spatial model are presented on the basis of a basic assessment and positioning. This is followed by a map of windows of opportunity and the start of a growing project map with "good practice" examples in the spirit of the sponge city. A comprehensive catalog of measures (including analytical, structural-spatial, procedural and communicative measures) prepares the implementation of sponge city measures and also serves to implement requirements in relevant administrative processes. In addition, model projects are outlined for five locations in Bonn, which are to be further developed and implemented in the ongoing process. Finally, a communication concept with an online platform as a central element is presented.