- Climate change
- Water, urban planning and sustainable development
- Nature-Based Solutions (NBS)
- Rainwater
World Soil Day: healthy soils for cities resilient to water and climate change
Every 5 December, World Soil Day reminds us of the vital importance of these ecosystems for food security, biodiversity... and climate resilience.
The 2025 theme, ‘Healthy soils for healthy cities’, highlights a major issue: in urban areas, soil quality directly affects water management, flood control, heat island prevention and climate change adaptation.
Soil, water and climate change: a fundamental link
In cities, the widespread waterproofing of surfaces (roads, car parks, roofs) prevents rainwater from infiltrating the ground.
The results: excessive runoff, increased risk of flooding, overloaded sewer systems, and higher urban temperatures, as dry soils no longer have the ability to cool naturally.
Conversely, living, permeable, vegetated soils play an essential role:
- They absorb rainwater thanks to their infiltration capacity.
- They store water, supporting vegetation and regulating temperatures.
- They filter pollutants, improving water quality.
- They limit flooding by reducing runoff.
- They mitigate urban heat islands.
These ecosystem services are at the heart of Nature-Based Solutions (NBS), which are now essential in the development of sustainable cities.
OiEau plays a central role in developing expertise and disseminating integrated water management practices in cities, focusing on three key areas:
- Promoting Nature-Based Solutions (NBS)
Through training, expertise and support for local authorities, OiEau encourages the integration of swales, green trenches, rain trees, green roofs, permeable paving and other circular water management solutions.
- De-impermeabilisation of urban spaces
OiEau demonstrates, by example, that de-impermeabilisation is the key lever for restoring water to its place in natural cycles.
This approach is at the heart of the renaturation of its Limoges site (see below).
- Sustainable rainwater management
L'OiEau trains professionals and supports local authorities in moving towards more resilient, less costly and more environmentally friendly rainwater management.
Renaturation of the Limoges site: a full-scale demonstration project
The OiEau site in Limoges has been completely redesigned to become a veritable educational showroom for innovative urban water management methods, with financial support from the Loire-Bretagne Water Agency.
This renaturation project is based on three pillars:
✔️ Massive de-impermeabilisation of 3,500 m² thanks to:
- porous-surfaced car parks,
- vegetated swales and trenches,
- rain trees,
- re-infiltrating soils that promote the return of water to the ground.
✔️ Large-scale greening with the planting of more than 750 trees and shrubs, 120 climbing plants, numerous bulbs, perennials and seedlings.
This greening contributes directly to:
- the reduction of heat islands,
- water retention in the soil,
- local biodiversity.
✔️ Integrated stormwater management
The site aims to completely disconnect from the community's stormwater network, ensuring complete infiltration on site. The initial actions taken (green roofs, storage of 2 m³ of rainwater for sanitary facilities, porous car parks) have been reinforced by a more ambitious renaturation plan.
Today, the complex is a unique educational tool, used in training courses on integrated and resilient stormwater management.
Healthy soils at the heart of future cities
The renaturation of urban soils is a key issue in building cities that are:
- safer in the face of extreme rainfall events,
- cooler during heatwaves,
- more resilient to climate change,
- more pleasant and more vibrant.
World Soil Day reminds us that the health of urban soils is inextricably linked to the health of citizens. By promoting infiltration, biodiversity, greening and sustainable water management, OiEau and its partners are leading the way towards more sustainable and resilient urban spaces.
The ‘Cities & Basins’ handbook: connecting territories and resources
This practical manual, published by the International Network of Basin Organisations, for which OiEau provides the Technical Secretariat, proposes an innovative approach to linking urban issues with those of river basins.
It offers local authorities concrete tools to:
- improve coordination between local actors;
- plan sustainable actions;
- promote shared governance around water.
To learn more, discover our projects related to stormwater management in cities
