Urban Regeneration: Tools for Building Resilient Cities

Adopted at the United Nations Habitat III Conference in 2016, the New Urban Agenda sets a shared vision: to make cities and human settlements inclusive, safe, resilient, and sustainable.

As urban densification accelerates, territories are confronted with compounding challenges—ranging from urban sprawl and air pollution to soil sealing and aging infrastructure - all while climate disruption poses severe threats to public safety and well-being, notably through summer heatwaves and flash flooding triggered by intense precipitation events.

In response to these risks and vulnerabilities, public authorities and decision-makers must deliver sustainable, resilient urban regeneration strategies that guarantee adequate housing for all.

Within this framework, water management has emerged as a cornerstone of urban climate adaptation and regeneration policies. This approach champions circularity, water reuse, and the restoration of urban ecosystems and biodiversity. By embedding Integrated Water Resources Management (IWRM) into the early design and redevelopment phases of urban projects, local authorities can restore the natural water cycle, mitigate flood vulnerability, and deliver long-term reductions in urban heat island effects.

Faced with mounting anthropogenic and climate-relatedpressures, conventional pipe-bound stormwater management approaches have laid bare their limitations. Fostering metropolitan resilience requires rethinking spatial scales of analysis and reconnecting cities with their broader ecological hinterlands.

• Territorial Solidarity and the City-Basin Dialogue

Urban resilience must encompass the natural hydrological scale of the catchment area. Co-published by the International Network of Basin Organizations (INBO / RIOB) and the International Water Association (IWA), the City-Basin Dialogue Handbook operationalizes this integrated approach. It posits that establishing a sustained city-basin dialogue serves as a critical mechanism to advance sustainable water management - enhancing source-water protection both within and across municipal boundaries, securing water quantity and quality, and equipping cities to withstand climate change impacts. 

This framework provides public decision-makers with strategic guidelines to align drinking-water catchment protection, restore flood-retention zones, and optimize infrastructure capital investments across coherent jurisdictional scales.

• Controlling Diffuse Pollution and Urban Runoff

Surface sealing means heavy rainfall inevitably drives urban runoff, contaminating natural ecosystems and urban aquatic environments. Within the European Waterun project, OiEau and its consortium partners are developing Water Sensitive Urban Design (WSUD) methodologies through a holistic lens—from source identification to policy decision-making for diffuse water pollution control across urban catchment basins. 

The objective is to modernize diffuse pollution management by deploying diagnostic, spatial-planning, and risk-assessment toolkits, alongside novel cross-sector operational protocols engaging key urban water management and governance stakeholders.

• The “Sponge City” Concept and Nature-Based Solutions (NbS)

Long driven by the legacy pipe-and-drain paradigm designed to discharge stormwater off-site as rapidly as possible, spatial planning is pivoting toward the "sponge city" concept. The governing principle is straightforward: infiltrate, retain, and evapotranspire rainwater directly at source.

Depaving and natural percolation rely on cost-effective, multifunctional design elements:

• Vegetated swales and infiltration trenches: broad, shallow drainage swales that attenuate runoff flow while biofiltering pollutants through engineered soil media.
• Rain gardens and open-air retention basins: integrated into urban parks or school grounds to deliver dual benefits in stormwater regulation and urban amenity.
• Permeable pavements: porous asphalt, permeable interlocking concrete pavers, and reinforced gravel grids deployed across parking facilities and low-traffic roadways.

OiEau is actively engaged in the SpongeWorks and SpongeScapes projects. These collaborative programs co-design, model, and scale Natural Water Retention Measures (NWRM) across metropolitan areas and river basins, generating empirical evidence on their resilience to both drought events and flash floods.
Stormwater is no longer managed as wastewater requiring urgent offloading; instead, it is harnessed as a strategic asset to sustain green and blue infrastructure and alleviate reliance on mechanical air conditioning.

The European NATALIE project aims to demonstrate the effectiveness of Nature-based Solutions (NbS) in addressing climate hazards (flooding, wildfires, droughts, etc.) threatening regional ecosystems.

Its deployment model relies on establishing Demonstration Sites (DS) where NbS interventions are field-tested, often paired with Follower Sites (FL) to assess scalability and replication potential.

Several case studies specifically target urban and peri-urban environments:

• Freshwater Habitat Restoration in Urban Ecosystems (Romania): this case focuses explicitly on re-naturing and preserving water bodies directly within the urban fabric, reconciling flood risk management, water quality enhancement, and public access to nature for city dwellers.

• Managed Aquifer Recharge for Water Reuse (Belgium / Flanders): in high-density settings such as Flanders, groundwater resource stewardship presents a strategic imperative. This project highlights methods for buffering severe drought impacts across heavily human-impacted areas.
• Alternative Water Management Solutions in Archipelagos (Spain): While insular in geography, water stress in the Canary Islands and the Balearic Islands (the follower site) directly impacts freshwater security across high-density urban and tourist hubs.
• Sustainable River Restoration, Maintenance, and Management in Veneto (Italy): Situated within a densely populated region, this case study targets flood prevention measures to safeguard surrounding urban centers.

OiEau provides hands-on advisory services to local authorities and public decision-makers, helping bridge policy ambitions and long-term urban regeneration outcomes.

• Decision-Support and Methodological Engineering

With the French Office for Biodiversity (OFB), OiEau delivered in 2025 operational and technical guidance notes on NWRM for project owners, with a focus on built environments. These resources inform technical procurement, outline implementation protocols, and identify statutory funding levers available in France.

• Capacity-Building and Workforce Upskilling

In response to evolving regulatory mandates, OiEau delivers tailored training curricula on Urban Stormwater Management (GEPU) and Integrated Stormwater Management (GIEP). Designed for elected officials and civil servants navigating newly devolved local government competencies, these programs facilitate the rollout of climate-resilient solutions.

OiEau also operates a dedicated educational and testing facility in Limoges specializing in integrated stormwater management. This technical demonstrator allows professionals to inspect and test permeable pavements, infiltration techniques, and flow-attenuation systems under real-world operational conditions.

• Financial Sustainability and Asset Management Planning

Retrofitting utility networks and developing green infrastructure necessitates complex budgetary trade-offs. The ProsperEau decision-support platform, designed by OiEau, provides local authorities with multi-year financial modeling and asset management forecasting for municipal water and sanitation services. It enables public stakeholders to project operational lifecycle costs, schedule infrastructure asset renewals, and assess capital expenditure requirements against climate adaptation benchmarks to ensure uninterrupted, high-quality public service delivery.

By providing technical, methodological, and strategic planning support to regional and local stakeholders, OiEau contributes directly to the operationalization of urban resilience and climate adaptation targets. To guarantee adequate housing for all, spatial development frameworks must position integrated water stewardship as an indispensable cornerstone of urban planning and territorial solidarity.