How does a nature-based solution for flood control compare to a technical solution? Case study evidence from Belgium.

The strategy of reconnecting rivers with their floodplains currently gains popularity because it not only harnesses natural capacities of floodplains but also increases social co-benefits and biodiversity. In this paper, we present an example of a successfully implemented nature-based solution (NBS) in the Dijle valley in the centre of Belgium. The research objective is to retrospectively assess cost and benefit differences between a technical solution (storm basins) and an alternative NBS, here the restoration of the alluvial floodplain. The method is a comparative social cost-benefit analysis. The case study analysis reveals similar flood security, lower costs, more ecosystem services benefits and higher biodiversity values associated with the NBS option in comparison to the technical alternative. However, the business case for working with NBS depends substantially on the spatial and socio-ecological context. Chances for successful NBS implementation increase in conditions of sufficient space to retain flood water, when flood water is of sufficient quality, and when economic activity and housing in the floodplain is limited.

A novel telecoupling framework to assess social relations across spatial scales for ecosystem services research.

Access to ecosystem services and influence on their management are structured by social relations among actors, which often occur across spatial scales. Such cross-scale social relations can be analysed through a telecoupling framework as decisions taken at local scales are often shaped by actors at larger scales. Analyzing these cross-scale relations is critical to create effective and equitable strategies to manage ecosystem services. Here, we develop an analytical framework -i.e. the 'cross-scale influence-dependence framework'- to facilitate the analysis of power asymmetries and the distribution of ecosystem services among the beneficiaries. We illustrate the suitability of this framework through its retrospective application across four case studies, in which we characterize the level of dependence of multiple actors on a particular set of ecosystem services, and their influence on decision-making regarding these services across three spatial scales. The 'cross-scale influence-dependence framework' can improve our understanding of distributional and procedural equity and thus support the development of policies for sustainable management of ecosystem services.

Researchers must be aware of their roles at the interface of ecosystem services science and policy.

Scientists working on ecosystem service (ES) science are engaged in a mission-driven discipline. They can contribute to science-policy interfaces where knowledge is co-produced and used. How scientists engage with the governance arena to mobilise their knowledge remains a matter of personal choice, influenced by individual values. ES science cannot be considered neutral and a discussion of the values that shape it forms an important part of the sustainability dialogue. We propose a simple decision tree to help ES scientists identify their role and the purpose of the knowledge they produce. We characterise six idealised scientific postures spanning possible roles at the science-policy interface (pure scientist, science arbiter-guarantor, issue advocate-guardian, officer, honest broker and stealth issue advocate) and illustrate them with feedbacks from interviews. We encourage ES scientists to conduct a reflexive exploration of their attitudes regarding knowledge production and use, with the intention of progressing toward a higher recognition of the political and ethical importance of ES assessments.