Compare governance models
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Aarhus
Tampere
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Aarhus
Tampere
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NBS model
Aarhus
Formalized catchment planning. Municipality led model.
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STRATEGIC GOVERNANCE
CATCHMENT-FIT NBS DELIVERY
ADAPTIVE CAPACITY
Catchment-fit NBS deployment is well integrated to Aarhus city policies. It is not a single a strategy or regulation enabling the policies, but rather a system approach that has been built brick-by-brick over the course of time. The political support get's its rationale and goals from both EU & national level regulations as well as data based evidences like climate projections and risk assessments. The It is formalized through the city's governance structure and role division, but many local strategies and plans, most noteworthy being the stormwater strategy, the city masterplan, the blue-green theme plan, and the two-level catchment-based stormwater management plan. These documents enable stable funding, clear procedures, control over role division and streamlined practices across the different municipal functions that enable the catchment-fit NBS deployment.
Political support
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Aarhus water utility applies cost-efficient nature based solutions that respond to Best Available Technology model (BAT) to reduce pressure to drainage system network. This widens also to privately developed areas, where NBS deployment can be partially funded by water utility, this does not only include investments, but also routine maintenance of the solutions. The BAT funding guarantee helps municipality and developers implement stormwater detention ponts as a routine element of drainage network.
Financing model
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Catchment-scale planning focuses on greenfield zones where NBS can be embedded into the master design from the outset.
Catchment integration
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Engineering design tailored to the catchment criteria, with monitoring plan and maintenance handover specified upfront.
Design of NBS
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The constructed system performs hydraulically as a single NBS unit (XS), is integrated into plot-scale landscaping (S) and the surrounding development area (M), and contributes to catchment-scale stormwater objectives (L). One built artefact, four scales of fit — the signature of the Aarhus model.
L — Catchment (click to filter)
M — Development area (click to filter)
S — Plot (click to filter)
XS — NBS (click to filter)
XS — NBS (click to filter)
NBS INTEGRATION SCALES
Utility constructs NBS as part of its drainage works, treating them as standard assets in the system.
Construction of NBS
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Long-term operations and maintenance are owned by the utility, ensuring catchment performance over the asset lifecycle.
Maintenance of NBS
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Pilots feed structured learning into the next generation of designs and into mainstream catchment policy.
Evaluation and learning
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Tampere
Formalized catchment planning. Municipality led model.
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STRATEGIC GOVERNANCE
CATCHMENT-FIT NBS DELIVERY
ADAPTIVE CAPACITY
Catchment-fit NBS deployment in Tampere has gradually evolved from individual pilot projects into a mainstream municipal stormwater management approach. Political support has been strengthened through recurring flood risk concerns, ecological protection of urban lakes and streams, and positive public reception of multifunctional blue-green environments. The governance model is strongly municipality-led, with stormwater management integrated into several strategic and operational documents, including the City Strategy, Mayoral Programme, Biodiversity Programme, Stormwater Strategy, and land-use planning procedures. National stormwater requirements and municipal guidance frameworks further support local implementation. Over time, Tampere has institutionalized NBS as a routine component of urban development and climate adaptation policy.
Political support
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Tampere applies a municipally coordinated financing model where a dedicated stormwater fee provides long-term funding for both construction and maintenance of NBS. The city primarily finances NBS implementation on public land, while private actors contribute indirectly through stormwater fees and compliance with planning requirements. Funding is not limited to hydraulic performance alone, but also supports biodiversity, recreation, placemaking, and urban liveability objectives. Stable annual investment planning allows NBS implementation to continue systematically across catchments and development projects.
Financing model
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Tampere applies catchment-scale stormwater planning supported by city-level hydraulic modelling and flood risk assessments. Catchment planning is commonly outsourced to specialized consultants but coordinated and reviewed by the municipal stormwater management team. The planning process prioritises sub-catchments with chronic flood risk and sensitive receiving waterbodies while integrating NBS into broader land-use and urban development planning. Stormwater plans establish runoff criteria and define the principles for maintaining hydrological status quo in developing areas. Existing natural systems, open ditches, waterways, biodiversity values, and future flood routes are considered as part of the planning process.
Catchment integration
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Detailed NBS design is outsourced through framework contracts to experienced engineering and landscape design consultancies. Designs are guided by municipal stormwater criteria, catchment planning outputs, and interdisciplinary review processes involving stormwater specialists and experts from multiple municipal departments. Tampere's approach emphasizes multifunctionality: NBS are designed not only for runoff control, but also for biodiversity, urban quality, recreation, and ecological connectivity. Monitoring requirements and maintenance responsibilities are increasingly considered already during the design phase.
Design of NBS
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Construction is coordinated by the municipal stormwater management team, which supervises implementation and ensures that catchment-scale objectives are preserved during delivery. Although construction itself is outsourced to contractors, municipal stormwater specialists play a strong role in site supervision and coordination. Over time, Tampere has developed a capable local market of contractors and consultancies familiar with catchment-fit NBS implementation.
Construction of NBS
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NBS are maintained by municipal maintenance departments as part of the public urban infrastructure system. Maintenance activities are coordinated and clustered through GIS-based asset management systems that group similar maintenance tasks across the city. The stormwater fee supports long-term operational capacity, while maintenance routines increasingly recognize the ecological and multifunctional nature of NBS assets.
Maintenance of NBS
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Multi-scale catchment-fit NBS — XS to L scales.
L — Catchment (click to filter)
M — Development area (click to filter)
S — Plot (click to filter)
XS — NBS (click to filter)
XS — NBS (click to filter)
NBS INTEGRATION SCALES
Tampere has institutionalized adaptive learning within its stormwater governance model. Monitoring data, flood events, maintenance experiences, and project evaluations are systematically discussed within the municipal stormwater department through regular internal review meetings. Learning is used to improve future planning criteria, technical guidance, maintenance practices, and project coordination. Monitoring has demonstrated that NBS have effectively maintained or reduced runoff loads and pollutant concentrations despite urban development, strengthening political and institutional support for continued implementation.
Evaluation and learning
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