Blue and Green Solutions Adaptation tools to mitigate global change in urban environment

Green roofs and facades, valleys, storm gardens, retention basins... Blue and green infrastructures are becoming increasingly common in our urban spaces. In recent years, they have become much more widespread with the development of ZACs (zones d'aménagement concerté) and the emergence of eco-neighborhoods. Initially based on aesthetic criteria or water management issues, the multiple ecosystem services provided by these infrastructures (thermal and acoustic insulation, reduction of urban heat islands, preservation of biodiversity) are now being put forward to encourage their widespread use. As part of a process of urban renaturation, they can represent effective tools for combating the effects of climate change, while developing a sustainable, more pleasant city for its inhabitants.

Although these ecosystem services are well established, they are still poorly understood and evaluated. What's more, the many rules and laws in force to promote their implementation often make no explicit reference to them. For the most part, they are limited to setting out the objectives to be achieved, without detailing how they are to be achieved. Against this backdrop, the aim of this article is to provide a broad overview of current knowledge on blue and green infrastructures. Intended to be practical, it presents the existing regulatory and technical tools – as well as their limitations – to facilitate the implementation of these structures and assess their ecosystem services right from the planning stage. This multi-disciplinary document is aimed at a wide audience, including engineers, architects, planners, local authorities, teachers and students.

To this end, the article is structured as follows. First, it recalls the current context in which this renaturation of urban space is taking place. It presents the different types of blue and green infrastructure that can be found in development projects today, highlighting the advantages and disadvantages of each. It then reviews the standards, regulatory constraints and certifications that can facilitate the implementation of these structures. It then lists the various ecosystem services that these infrastructures can provide, detailing the physical processes involved, and how they can be represented and modeled. The article concludes with a presentation of existing operational tools that can be used to quantitatively assess these services.