Résumé
Global changes (climate change, diffuse agricultural pollution, urban sprawl) represent a significant challenge for society, threatening the sustainable management of groundwater and biodiversity. Nature-based solutions for sustainable groundwater management (NBS-GW) can mitigate these effects by influencing groundwater recharge and quality, and make territories more resilient to global changes. These solutions can be implemented in a diversity of contexts: i) agro-forestry environments (forest, agro-ecological practices and infrastructures, semi-natural grasslands), ii) urban and peri-urban environments with green infrastructure aiming to increase permeability in the city, as well as iii) aquatic ecosystems (wetlands restoration, river renaturation, managed aquifer recharge through vegetated basins). Although the potential effects on groundwater are recognized as significant in the literature under certain conditions of climate, vegetation, watershed topography, and geology, there is a lack of experience feedback. This may be because these solutions are still rarely mobilized with a sustainable groundwater management objective in mind, which leads to solutions generally not implemented at the appropriate scale, and without an adequate impact monitoring system. Therefore, there is a strong need to demonstrate the evidence of the effectiveness of these solutions to integrate them into groundwater management plans.Our research, conducted in partnership with the French Rhône Méditerranée Corse Water Agency, analyses ex post the effects of NBS programs on groundwater and society using three case studies in France in three different environments (aquatic, agricultural, urban). We use a multidisciplinary approach combining hydrogeological tools, semi-structured interviews with local stakeholders, and surveys with citizens to evaluate NBS-GW by intersecting their hydrogeological effects with the diversity of values and perceptions of local stakeholders. In the Drugeon watershed, the river renaturation program and peatland rehabilitation implemented to restore aquatic biodiversity help mitigate the effects of climate change on aquifers while reducing greenhouse gas emissions. In the case of the Vistrenque-Costières area, the biodiversity offsetting program, through the promotion of semi-natural grasslands, allows for the restoration of the quality of the aquifer used for drinking water supply while creating habitat for an endangered species. In the case of the East Lyon territory, we show that alternative rainwater management solutions can avoid aquifer depletion due to urbanization as well as providing a diversity of environmental benefits to urban dwellers . In general, these results highlight strong potential synergies in the effects of NBS-GW on biodiversity, climate, society and groundwater issues, therefore calling for greater coherence between public policies (Water, Climate, Biodiversity), aiming to enhance the resilience of watersheds to global changes.