8. When Constraints Become Assets in the Design of Blue-Green Infrastructures: An Insight from Two Cases in the Western Part of France (Loire River Basin)

This chapter focuses on projects of blue-green infrastructures (BGI) located in two middle-sized French cities in the Western part of France, on the Loire river basin (the Ile aux Planches urban park in Le Mans and the Parc Balzac in Angers). They constitute illustrations of recent and innovative approaches in the design of BGI in France. In both cases, planners had to face major challenges, whether technical or political. Innovative solutions were found to overcome technical difficulties (projects located in flood-prone areas, on brownfield sites and facing heavy pollution). Local oppositions and strong involvement of inhabitants forced planners to redefine and improve their projects. We point out how planners successfully turned those various constraints into assets and synergies to design multifunctional BGI in both cases. However, when comparing the projects, we see important differences. In Parc Balzac, planners clearly succeeded in designing a project with strong synergies between its various functions (biodiversity protection, leisure and education to environment, flood risk management). In the case of the Ile aux Planches, in Le Mans, synergies are not so obvious. In a broader perspective, this chapter questions the concept of BGI and its capacity to address the question of synergies between functions in green parks.