Preferences for nature-based solutions aiming at reducing flood risks. Results of a Discrete Choice Experiment in the Lez catchment (France)

Nature-based solutions (NBS) are increasingly being promoted as a means of reducing water-related risks, particularly flood risks. These solutions can also generate a wide range of co-benefits (e.g., climate regulation, air quality regulation, reduction of urban heat islands), and may pose some constraints in contexts with high population growth and urban development. Understanding and evaluating these co-benefits and constraints can be a lever to facilitate the implementation of these solutions.

We implement a Discrete Choice Experiment survey in the Lez catchment (France) to assess residents’ preferences for different types of NBS and levels of implementation and to evaluate the monetary value of NBS co-benefits. We consider two types of NBS: i) the conservation of natural and agricultural land (by limiting urban sprawl) and ii) the introduction of green infrastructure into the city.  

The results obtained from 400 households living in the Lez basin show that people associate many co-benefits with NBS and that these co-benefits are greater than constraints. The econometric analysis reveals that respondents prefer the most ambitious levels of NBS implementation. The mean overall amount residents are willing to pay for the co-benefits generated by NBS are estimated between 133€ and 178€ household/year depending on the NBS types and levels of implementation. Results also show significant levels of heterogeneity of the preference for NBS between respondent types.

This analysis confirms that people attach an economic value to the co-benefits associated to NBS primarily aiming at reducing flood risk. It gives insights to understand i) which category of population is more or less in favour of different NBS solutions and ii) which co-benefit is particularly influencial in the value granted by the population to the proposed NBS strategies. This application of the Choice Experiment methodology is one of the first application of the methodology to the evaluation of NBS. This work was carried out as part of the EU H2020 NAIAD project.