Can NBS Address the Challenges of an Urbanized Mediterranean Catchment? The Lez Case Study

Abstract The Lez catchment is characterized by a rapid urbanization, due to the attractiveness of the city of Montpellier, and is exposed to a typical Mediterranean weather with high risk of flash flood and other emerging issues, such as air pollution, heat island effects and biodiversity losses. We present the evaluation of two types of NBS to address these challenges, (i) urbanization strategies that have an impact on the conservation of agricultural and natural land and (ii) a network of green infrastructure (GI), with a focus on the economic analysis. Our results reveal that our most ambitious GI strategy can reduce up to a 20% of the mean annual damages due to annual flood damages. The largest share of the economic value of our NBS however lies in the co-benefits they generate. Overall, the two GI strategies present a positive cost-benefit analysis. We finally identify a pathway towards implementation in terms of financing and organizational challenges.