Luis Touriño on… Sponge Cities and Green Infrastructure

From your experience in the Spanish context, what nature-based policies and frameworks could be adopted at the local level to mitigate the dangers of flooding and poor water management?

The first step is to thoroughly understand the risks urban areas face, especially where the relationship with rivers has been complicated or unnatural. Modeling hydraulic scenarios considering climate change helps identify those risks and design solutions that increase resilience to flooding.

At the local level, an urban renaturalization plan—or a green infrastructure plan including climate adaptation—is the key tool to address these challenges. This plan must be aligned with the municipality’s main spatial planning instrument to ensure coherence and effectiveness.

Furthermore, fostering inter-administrative cooperation with hydraulic authorities is essential so that hydrological plans and risk mitigation plans include specific nature-based solutions in urban settings. This approach was promoted by EOSA in Pontevedra, with positive outcomes.

The concept of “Sponge Cities” has gained traction in urban water management discourse, particularly following successful implementation in China. How would you assess the transferability of this approach to Spanish (and European) urban contexts, considering the distinct climatic, spatial, and governance frameworks?

I believe the transfer of the “Sponge Cities” concept is not only feasible but necessary in Spain, especially as climate change increases the risk of flooding from torrential rains.

One key problem in our cities is the occupation of natural spaces near rivers and flood zones, which limits their capacity to respond to water. Improving water infiltration in urban areas not only reduces flooding but also enhances the city’s metabolism and biodiversity.

Working in this direction requires intense dialogue with urban planners and architects, not only during planning but also throughout the execution of interventions aimed at reducing impervious surfaces. Coordination among all involved administrations is also fundamental to pooling efforts.

At EOSA, we support the Galicia regional government in scaling up this concept, with participation from Augas de Galicia in the Interreg Europe Resurexion project, which develops multilevel strategies for urban resilience and basin management against extreme weather. This international collaboration will help improve policy instruments in Galicia to strengthen the Sponge City concept in urban projects with municipalities to reduce flood risk.

Which existing examples of water-resilient cities stand out to you as potential models for European cities to follow? Why?

There are several outstanding examples in Europe of innovative and successful water-resilient management through green infrastructure and nature-based solutions.

Malmö, Sweden, is an emblematic case and received the UN-Habitat Award for its integrated stormwater management in urban neighborhoods and commitment to green infrastructure that absorbs and stores water, reducing flood risk while creating quality green spaces for residents. Malmö has successfully combined climate resilience with high-quality public spaces.

Recently, I visited Arnhem, Netherlands, where flood risk was reduced by increasing the river section near the city using green solutions. These measures manage high flows, boost biodiversity, and provide recreational areas, achieving a balance between functionality and quality of life. The total investment was around 25 million euros.

In Spain, Vitoria-Gasteiz suffered severe flooding issues, especially in its industrial park, due to soil impermeabilization and artificial canalization of rivers and streams. The creation of the “Green Belt” and, particularly, the restoration of the Salburua Wetland have been fundamental in reversing this situation. This natural system acts like a sponge that retains and filters rainwater, significantly reducing flood risk, alleviating pressure on urban infrastructure, and enhancing biodiversity while offering high-quality natural spaces for the city.