The City of Aachen’s administration views the BlueGreen City Coaching as a welcome and structured form of support to advance necessary developments in a targeted and integrated manner, in light of the politically and legally defined goals for a future-oriented transformation of the city. Our objective is to establish permanent interdisciplinary structures and to develop viable solutions for joint investments, their financing, and the long-term maintenance of Blue Green Infrastructure (BGI), such as for multifunctional land uses. Key challenges include integrated planning in urban areas particularly affected by heavy rainfall and heat, early coordination of underground space uses, and the systematic implementation of multifunctional blue-green spaces — even within the city’s historic district under heritage protection. Additionally, we aim to establish coordinated communication with private property owners, investors, architects, engineers, and other urban stakeholders to jointly address heavy rainfall and flood prevention, and to make rainwater usable locally.

A central goal is the firm anchoring of BGI as a planning and solution approach in all relevant planning, construction, and renovation processes. This requires a shared understanding, clear commitment, and assumption of responsibility from the outset — as well as empowering our staff to independently develop Blue Green City topics further. Trust in the administration, politics, and civil society, along with appropriate formats for exchange with the public, experts, and stakeholders, are crucial for us. We expect the coaching to provide impulses for practical technical, organizational, and communication solutions, which we can test collaboratively, as well as to strengthen network-building — both within Aachen and with other municipalities and experienced partners.

Dr. Silke Roder
Abteilungsleitung Tiefbau
Fachbereich Mobilität und Verkehr der Stadt Aachen
Lagerhausstr. 20
52078 Aachen
Tel.: 0241-432 68500

The effects of the climate crisis are becoming very evident in Braunschweig. There have been several heavy rainfall events, some of which caused significant property damage. For example, on June 22, 2023, large parts of the city experienced a severe downpour, with over 80 liters of rainfall per square meter within one hour. The fire department reported that it had not witnessed such a storm in the past 30 years. Within a very short time, basements, streets, and underground garages were flooded. On the other hand, heat and drought are increasingly affecting the city, agriculture, and green spaces. Within the framework of its Integrated Urban Development Concept and the COABS project, Braunschweig has made a clear commitment: the city aims to adapt to more frequent extreme weather events, reduce urban heat stress in heat island areas through integrated planning approaches, and pave the way for more Blue-Green(-Grey) Infrastructure, or sponge city development.
By networking with other cities, a broad spectrum of practical solutions can be developed.

However, the current administrative structure is not yet designed to handle such complex, interdisciplinary tasks like the establishment of Blue-Green Infrastructure. At present, individual organizational units implement pilot projects and conceptual plans. Cross-departmental working groups with decision-making authority are lacking. When assessing the costs of Blue-Green measures, the focus is often on short-term implementation, as long-term savings are difficult to demonstrate and communicate. In addition, legal questions must be clarified and statutory amendments reviewed.

We hope the coaching will provide an initial boost. Blue-Green approaches must become part of everyday practice, not just showcase projects. If the coaching can help answer structural questions — such as possible responsibility arrangements, funding options, legally secure scopes of action, and more — then large-scale implementation of "Blue-Green measures" will become attainable.

“Joint Development of a Declaration of Intent for Blue-Green Urban Development”

Even before the municipal elections (13 September 2026), the coaching team and the city will prepare a report on blue-green urban development for the Braunschweig Conference of Department Heads. This will serve as a preliminary step towards a draft proposal for the City Council, which is to be completed by spring 2027. The draft should comply with the provisions of the Lower Saxony Municipal Constitution Act (NKomVG). It should be relatively short and clearly formulated in terms of its objectives and, ideally, serve as a model with regard to the level of detail and flexibility of the objectives. Key topics of the draft proposal for the City Council include: benefits of blue-green infrastructure for Braunschweig; costs (including options for financing through fees); legal requirements to identify and redefine responsibilities where gaps currently exist, for example in stormwater management (heavy rainfall risks); a mandate for the administration to review existing requirements.

Stadt Braunschweig, FB 61, Referat Grün- und Freiraumplanung: 

Fr. Melanie Huk, Emailadresse: melanie.huk@braunschweig.de 

Hr. Martin Altrock, Emailadresse: martin.altrock@braunschweig.de

For successful municipal climate adaptation, an integrated approach involving various departments, administrative offices, and municipal enterprises is essential. In this context, we hope to gain added value in terms of suitable organizational forms for integrated action.

With the development of the municipal integrated climate adaptation plan, the implementation of blue-green infrastructures is becoming a particular focus. Through cost-benefit analyses (including soft factors of ecosystem services), we aim to highlight the economic and social benefits of the measures, while also gathering further arguments in favor of nature-based solutions and making them understandable to the urban society, other departments, and political decision-makers (e.g. promoting biodiversity, urban health, social interaction and equity, and reduced health costs). In addition, solutions should be identified to help translate theory into practice.

Since climate adaptation is a relatively new aspect of urban development, and many other areas are more strongly and traditionally anchored in legislation or norms, we further hope for support in legal reasoning to strengthen local climate adaptation efforts.

The Science City of Darmstadt is among the regions in Germany most affected by the climate crisis. Located in the Upper Rhine Graben, Darmstadt is one of the hottest cities in Germany, with a particularly high number of hot days and tropical nights. Heat waves are becoming more frequent, more intense, and last longer. In addition, increasing summer drought is causing dieback and loss of vitality in urban nature and city forests. A third major vulnerability is the increase in heavy rainfall, which repeatedly leads to local flooding and water-filled basements across the city.

Coaching expectations:

• Strengthening intermunicipal networking 
• Mutual learning from one another 
• Gaining new perspectives on known challenges
• Developing approaches to deal with limited budgets and staff shortages
• Identifying pathways from theory to practice
• Learning about funding opportunities for adaptation measures
• Support for an initial implementation initiative

Joint Development of a Micro-De-Sealing Catalogue

Topic 1: A systematic workflow is to be developed for the de-sealing of small-scale areas in public spaces. It should illustrate the interdependencies between the different steps and the various legal implications from the perspective of the potentially involved municipal departments. A distinction should be made between mandatory and additional work steps.

As the stated objective is to accelerate de-sealing projects and implement them on a broader scale, this framework should be used to identify steps at which the overall process can be accelerated through experimentation or process optimization. In addition, an inventory of small-scale areas suitable for de-sealing is to be compiled and their overall climate adaptation potential for the city assessed.

David Fleischmann

The City of Freiburg im Breisgau is highly vulnerable to extreme weather events such as heavy rainfall, flooding, and heatwaves due to its geographical location. Longer periods of drought also present the city administration with a wide range of current and future challenges. At the same time, due to high development pressure, the city administration is called upon to develop and implement climate-adapted and sustainable infrastructure solutions.
A major challenge is the limited availability of space in combination with high competing demands (e.g. supply and disposal infrastructure, mobility planning, accessibility, etc.). Implementation is further complicated by lengthy planning processes and the required interdepartmental communication.

Through the coaching, we expect targeted support in improving internal administrative communication and in the development of standardized systems and regulations. Additionally, we hope the coaching will foster exchange of experiences and closer knowledge transfer with the participating cities and municipalities.

“Blue-Green Infrastructure in Existing Streets – A Guide for Future-Oriented Planning in Freiburg”

The city and the coaching team will jointly develop a guide comprising a vision, principles, visualizations (for example, of planning details), and planning steps. It will provide a consolidated and informative overview of the standard process for integrating the planning and implementation of blue-green infrastructure measures into Freiburg’s existing municipal planning processes. The document is intended to define standard processes and establish principles, which will subsequently be supplemented by examples from Freiburg.

Using Markgrafenstraße as an example, coordination processes will be carried out and transferable standards for the planning and implementation of blue-green infrastructure measures will be defined.

The long-term objective of the guide is to ensure that the planning of blue-green infrastructure measures is considered at an early stage in street redevelopment projects, to define cross-departmental planning and coordination procedures through principles for blue-green infrastructure, and thereby to standardize the implementation of these measures.

Garten- und Tiefbauamt Stadt Freiburg, Leoni Knoll

In Göttingen, climate-adapted redesign of public spaces represents a key task for the future. We want to use the opportunities of the project to approach climate adaptation not just selectively, but strategically and in an integrated manner. Our goal is to develop, together with utility providers and other urban stakeholders, a viable vision and strategy for the sustainable integration of Blue-Green Infrastructure in the transformation of streets and squares. In doing so, we are building upon the Göttingen City Water-Heat Plan, our concept for heat- and water-sensitive urban development, the results of which we aim to embed in long-term municipal practice.

Multiple interests converge in street spaces: trees as effective heat protection often conflict with existing utilities and infrastructure, while the expansion of district heating alongside the preservation of existing networks further intensifies the competition for limited space. This is especially challenging in the historic city center, where the dense network of underground utilities complicates implementation. However, these areas also coincide with heat hotspots, making nature-based solutions as win-win measures more important than ever.
In addition, establishing Blue-Green Infrastructure is still a relatively new but important task. Processes for the installation and operation of systems — such as rainwater use, the deployment of cisterns, or the integration of sustainable irrigation techniques — must first be developed and tested.

From our participation in the project, we expect support in resolving conflicts between competing uses and in exploring new approaches to rainwater management, infiltration, and irrigation. It is also important for us to gain impulses for rethinking civil engineering practices and, in connection with this, to promote climate-oriented design of public spaces. Furthermore, we seek guidance on prioritizing decisions and developing measures that are both resource-efficient and synergy-oriented. The coaching should help us to consolidate the process initiated through the Göttingen City Water-Heat Plan, translate it into pilot actions, and thereby create long-term structures for a climate-resilient and livable urban design.

Review of the Feasibility of Blue-Green Infrastructure Based on Two Concrete Case Studies and Development of Transferable Solutions

1. Guiding Question:

How can the City of Göttingen implement blue-green infrastructure concretely and permanently in new and, as a priority, existing street spaces and areas – despite limited space, competing uses, and complex responsibilities or financing structures?

2. Coaching Objectives:

The work will be carried out using concrete case studies in order to assess feasibility and develop transferable solutions:

Case 1 “Comprehensive Reconstruction of Obere Masch-Straße”
Case 2 “Multifunctional Areas in the New Development District Lange Rekesweg”

1. Role and cooperation model for different elements of blue-green infrastructure based on the planning for the two model districts
2. Develop a financing logic and cost model for elements of blue-green infrastructure based on the planning for the Lange Rekesweg model district and for the new swale system in Obere Masch-Straße

3. Final Product:

Cooperation model including an agreement for the planning, operation, and financing of blue-green infrastructure.

Karina Schell, nachhaltigkeit@goettingen.de, 0551 400 3904

Gütersloh, as the largest municipality in the district, is an urban center in the region. The compact city center plays a key role as a service hub. Beyond the urban core, green spaces and bodies of water, as well as rural districts, characterize Gütersloh. The diversity of spatial structures leads to varied impacts and degrees of vulnerability to the consequences of climate change.

Participation in the BlueGreen City Coaching is appealing to Gütersloh for many reasons. There is a strong internal drive to implement existing plans for nature-based solutions. The need for action has long been recognized and acknowledged at all levels. However, the day-to-day implementation involves specific challenges. These challenges stem, in part, from the increased demand for cross-departmental cooperation, but especially from the naturally high number of planning guidelines and specialist interests to be taken into account due to the wide range of involved actors.

In addition to flood protection, it is also challenging to incorporate aspects of aquatic ecology and to address the increasing vulnerability to extreme weather events. Watercourse expansion for hydraulic flood protection should always be combined with renaturation measures to improve water body ecology. At the same time, groundwater retention during dry periods must be optimized. Available urban land is limited, and so are the future financial resources for maintaining these areas.

The City of Gütersloh hopes that participating in the coaching will lead to better cooperation between the Department of Green Spaces and the Civil Engineering Department, especially at the interface of flood protection and watercourse maintenance. There is strong interest in support for the implementation of existing concepts and for public engagement. Existing networks and administrative structures are to be strengthened. Achieving the set goals requires intensive multidisciplinary collaboration — both within the administration and between the administration and supervisory authorities. This is where the coaching should come in to support the municipality. It is important to us to take all aspects of nature-based solutions into account — sponge city, flood protection, urban climate, biodiversity — and to consider them collectively.

Blue-Green Reinterpretation of Standard Processes (“Gütersloh Standard for Eh-Da Processes”)

Together, a blue-green reinterpretation of standard processes (“Gütersloh Standard for Eh-Da Processes”) will be developed. The work focuses on process steps relating to public spaces (public street space, paths, squares, green structure planning), land-use planning, and flood protection. After the project period, the city administration can continue working on further identified topics using the same process.

Nadine Frey Dipl.-Ing.
Stadt Gütersloh
Fachbereich Tiefbau
Abteilung Stadtentwässerung / Team Überflutungsschutz
Nadine.Frey@guetersloh.de

The City of Herne, with approximately 162,000 inhabitants, is centrally located in the Ruhr region of North Rhine-Westphalia. Due to its location and its history as a mining and industrial city, Herne has a high density of settlement and development. The inner-city areas are strongly shaped by 19th-century urban patterns. A distinctive feature is the close interweaving of green spaces, former industrial and commercial sites, and residential areas. Due to its central location in the densely built-up Ruhr area and the high urban density, the City of Herne is strongly affected by the impacts of climate change — and this impact is expected to intensify in the future. For this reason, the city is already actively engaged in forward-looking, climate-resilient urban development to ensure and improve quality of life while accommodating necessary spatial and economic developments.

As part of the ongoing structural transformation, Herne is focusing on the conversion, reactivation, and remediation of industrial and commercial brownfields. This involves the development of high-quality research, service, residential, and commercial districts, as well as multifunctional open spaces and neighborhood parks that promote biodiversity, blue-green infrastructure, and attractive recreational areas for the public.

Herne expects the BlueGreen City Coaching to provide support in the further establishment, but also in the evaluation and review of the effectiveness of climate adaptation measures. The city also hopes for assistance in better communicating the added value of such measures to the general public.
Over the coming years, Herne will undertake a range of major projects and initiatives to expand blue-green infrastructure as part of large-scale urban development and funding programs.

Joint Development of Regulated Responsibilities for Blue-Green Infrastructure Elements as well as a Model Solution and Model Calculation for Disconnecting Stormwater from the Sewer Network in Potential Areas

The coaching assignment comprises two interconnected questions that will (initially) be addressed separately.

1. Definition of blue-green infrastructures as wastewater management facilities or water bodies in the context of municipal statutes:
   
   The main topic is the development of definitions for certain blue-green infrastructures as wastewater management facilities or water bodies and the responsibilities to be derived from this (municipal utilities, departments of the municipal administration).
   This will be developed for five blue-green infrastructure elements: tree trenches, (sealed) evaporation swales, watercourses, and traffic areas as retention areas (parking areas and streets).
   
   Questions to be clarified include: Who is responsible for the blue-green infrastructure or for individual components? What is the legal situation? What scope for discretion exists? How can water bodies and infrastructures be separated?
   
   
2. Preparation of a model calculation (rough) for the costs and benefits of disconnecting stormwater on municipal land from the sewer network through blue-green infrastructures in suitable potential areas:

Stadt Herne

Frau Julia Landowski
julia.landowski@herne.de

Frau Franziska Weber
franziska.weber@herne.de

FB Umwelt und Stadtplanung

Magdeburg is striving for future-oriented, climate-resilient urban development. The city sees BlueGreen City Coaching as an opportunity to better leverage existing potentials and overcome structural obstacles — such as institutional barriers or lack of resources. The aim is to integrate nature-based solutions like the sponge city principle more firmly into planning practice and to implement measures for heat prevention, rainwater management, and biodiversity promotion more effectively. In addition, Magdeburg expects impulses for better institutional anchoring of green infrastructure and for exchange with other municipalities.

Magdeburg faces numerous challenges in urban development:
A high degree of sealed surfaces and a traditionally car-centered infrastructure hinder climate resilience. In central locations, high usage pressure makes de-sealing and implementing green measures difficult. 
The linear layout along the Elbe River leads to fragmented green structures and obstructs ecological corridors. Moreover, recurring droughts and heatwaves are causing water stress in rivers like the Elbe, Schrote, and Sülze, as well as heat stress in existing green spaces.
Despite a high density of research institutions, the transfer of innovative concepts into municipal planning and practice is often hampered by institutional barriers or a lack of resources. Additionally, a high degree of population fluctuation — especially due to the student population — makes stable participation processes and the development of sustainable local networks more difficult.

Template for a Political Policy Resolution on Blue-Green Urban Development

The city and the coaching team will jointly develop a template for a political policy resolution on blue-green urban development. In particular, it will address legal and infrastructural requirements, challenges related to the urban water balance, and potential cost savings. The template is intended to serve as a model for the stormwater disposal concepts that are already required to be developed in the federal state.

Laura Hinze
Landeshauptstadt Magdeburg
Dezernat für Umwelt und Stadtentwicklung, Stabsstelle Klima
E-Mail: Laura.Hinze@stadt.magdeburg.de

The State Capital Mainz is adapting to the consequences of climate change. Together with a wide range of actors from the administration, municipal companies, politics, and the interested public, concepts such as the climate adaptation strategy and the heavy rainfall preparedness plan were developed, adopted, and are now being gradually implemented. As is often the case with transformational processes, complex challenges also arise in adapting to climate change — challenges that can only be addressed through interdisciplinary collaboration.

The BlueGreen City Coaching provided an interesting framework to bring together local expertise and commitment to action with external competence, in order to find implementation-oriented solutions.

The challenges are multifaceted. On the one hand, the topographic location of the State Capital makes it particularly affected by the impacts of climate change. On the other hand, new challenges require new forms of collaboration. In addition, there are structural challenges such as a tight budgetary situation and staff shortages.

The basis for solving complex challenges is the integration of (scientific) knowledge into (municipal) action. We seek practical support through scientific findings and creative solutions provided by the project partners.

Preparation of the Process for Implementing the City Council Resolution “2nd Green Belt”

The city and the coaching team will jointly develop a conceptual framework for the process of implementing the City Council Resolution “2nd Green Belt”. By the end of this process (February 2027), the participants will have a clear understanding of what the spatial extent could look like (strategic vision) and how the project should be structured and managed (interim objectives, milestones, tasks, responsibilities, timeline). This also includes identifying additional relevant stakeholders. Furthermore, the coaching process will provide answers to the question of how the green belt can be secured in the long term. For selected implementation options, the required investments and follow-up costs will be analyzed.

Paul Grünebach
Abteilungsleiter Klimaschutz und Klimaanpassung
paul.gruenebach@stadt.mainz.de

The City of Regensburg looks back on almost 2,000 years of history and has been in a continuous state of transformation ever since. Until around 1900, it remained almost unchanged, while the most significant expansion of the settlement area has taken place during the last three decades of growth. When it comes to climate change adaptation, historically shaped cities in particular often face serious challenges — and Regensburg is no exception: High surface sealing and a low proportion of green spaces increase the city’s vulnerability to extreme weather events such as heatwaves and heavy rainfall. In Regensburg, the term “stone city” often comes into focus. The city’s location directly on the Danube, Naab, and Regen rivers also exacerbates the risks of flooding. As a UNESCO World Heritage Site and protected monument ensemble, transformations in the historic old town are especially complex. Even beyond the city center, available land for further development is limited, as nearly all brownfield sites have been used up. The city’s constantly growing population demands further urban densification, which in turn threatens the loss of climate-effective green structures and increases land use competition.

In light of these challenges, the City of Regensburg actively applied to participate in the BlueGreen City Coaching program of the German Environment Agency. The aim is to bring the relevant departments and actors into constructive exchange through expert advice and close collaboration with professionals, and to analyze and optimize internal processes and structures. Through specialist input on ongoing initiatives, gaps should be identified and ways found to close them, so that blue-green measures can be implemented more efficiently and sustainable urban development can be advanced.

Preparation of the Political Policy Resolution “Regensburg Becomes a Sponge City”

The city and the BlueGreen City Coaching team will jointly develop a political policy resolution entitled “Regensburg Becomes a Sponge City”. The resolution will not only reaffirm the overall objective but also define relevant sub-objectives/orientation targets. It will also specify the requirements necessary for implementing the policy resolution and the consequences resulting from its implementation (for example, in terms of costs, resource consumption, and practical issues such as winter maintenance). The coaching team will research examples of similar resolutions from other cities to provide guidance for the wording.

Carina-Denise Lemke