Heatwaves such as those in 2015, 2018 and 2022, heavy rainfall and flooding on a large scale in 2021 and a period of drought that has persisted since 2018 make it clear that climate-adapted urban development is becoming increasingly important.
Sealed urban areas with little greenery and high density are particularly susceptible to the consequences of climate change. It gets particularly hot here in summer and rainwater cannot seep into the ground and be stored.
In Bonn, measures to improve the urban climate and prevent heavy rainfall and flooding have therefore been continuously implemented for several years. Drought prevention is also increasingly coming into focus. However, climate-adapted urban development requires major transformations and investments that cannot be implemented overnight. In order to be able to exploit the potential nevertheless, the city of Bonn is endeavouring to make use of funding opportunities from the state and federal government and in this way supplement municipal budget funds for the implementation of measures in Bonn.
Important climate adaptation measures include, above all, the unsealing and greening of surfaces and buildings as well as the increased planting of new trees, as they improve the urban climate and help to reduce the impact of extreme weather events.
Heavy rain prevention: the city provides comprehensive advice
To prevent damage caused by heavy rainfall and flooding, protective measures such as the renaturation of streams, the creation of retention areas and relief structures are also being implemented along Bonn's streams. Despite all the efforts that can be made, there is no one hundred percent protection against the consequences of heavy rainfall. It is therefore all the more important that building owners take precautions themselves. The city of Bonn offers a comprehensive range of advice on this.
Unsealing and greening of urban areas and buildings
The city of Bonn also has the direct opportunity to take action on its own land and buildings. Standards have been set for the construction of new municipal buildings, which also include climate protection and adaptation measures such as green roofs and façades. Climate adaptation measures are also being implemented in urban green spaces. One example is the pocket park in Von-Witzleben-Straße, which has also been upgraded in terms of urban climate through unsealing and near-natural greening.
However, at 86 percent, the majority of land and buildings in Bonn are privately owned. Through planning law, the city administration has the opportunity to set binding requirements for new construction vis-à-vis third parties. In Bonn, extensive green roofs in combination with photovoltaic systems are required as standard on suitable roof areas. In addition, depending on suitability, further measures such as green facades or tree planting are regulated by regulation.
In the private sector, the city of Bonn also relies on information and advisory services as well as funding programs to support climate-friendly conversions. The funding and advisory services for greening and photovoltaic systems as well as the advisory services offered by the Bonn Energy Agency (opens in a new tab) for the energy-efficient refurbishment of buildings have been in high demand from private owners for several years.
With the fruit tree campaign carried out in the fall of 2023, the city of Bonn is awarding 1,000 young fruit trees to interested citizens, thus promoting climate adaptation on private land in addition to increasing biodiversity.
A conceptual framework is required for the coordinated and targeted implementation of climate adaptation measures. The first conceptual work on climate adaptation took place in Bonn in 2013 as part of the integrated climate protection concept. The focus was on the question of what conditions need to be created in order to take greater account of climate adaptation issues in urban development. This question gave rise to the ZURES and MUTABOR projects, among others.
While ZURES (Future-oriented vulnerability and risk analyses as an instrument for promoting the resilience of cities and urban infrastructures) identified spatial priorities for action for heat prevention by preparing an urban climate analysis and created an important instrument for urban planning for the initial assessment of urban climate issues in the form of the planning information map, MUTABOR (Microscale Investigation and Activation of the City of Bonn's Technical and Planning Adaptation Capacity to Reduce Heat Stress) deals with the options for action and the potential for adaptation in Bonn in the area of heat. As part of the project, a catalog of measures was compiled, which was then examined for its cooling effect in the urban area.
Development into a sponge city
As already mentioned, a high proportion of green space is the key to climate-resilient urban development. The issue of drought is therefore highly relevant. Due to the increase in consecutive dry days and increased surface water runoff, water is escaping from the local water balance, which is why vegetation is increasingly suffering from drought, especially in the summer months. To meet these challenges, the city of Bonn is currently developing a concept for a water-sensitive city based on the model of the sponge city.
Since August 2023, a climate adaptation concept funded by the Federal Ministry for the Environment has been developed as a systematic superstructure for the city of Bonn's climate adaptation activities. Among other things, the concept focuses on taking stock of the projects already implemented and identifying key areas for action. With an implementation-oriented agenda of measures, climate adaptation in Bonn is to be concretized and gradually implemented in the city area.
The involvement of citizens and other stakeholders such as housing associations, public building owners, etc. is of great importance in order to effectively develop the entire city area in a climate-adapted way. As part of the creation of the integrated climate adaptation concept, public participation is therefore planned, which also includes the involvement of various stakeholders. The participation process for the climate adaptation concept will start in spring 2024. In view of the increasingly urgent need for climate adaptation, broad participation and support from all necessary actors and stakeholders is required in addition to municipal activities.