A meta-analysis of the value of ecosystem services of floodplains for the Danube River Basin.

Floodplains provide ecosystem services (ES). Their evaluation is complex and integrative assessment remains challenging for sciences and practices. Studies have been published in the last two decades reporting ES monetary values of floodplains. Since ES are site-specific, we focus on those studies regarding the Europe's second largest river basin, namely the Danube River Basin (DRB). By analyzing these studies, we aim to answer the questions: "Do the significant predictor variables differ from previous meta-analyses?" and "Does the spatial database improve the meta-analysis?" In this context, we conducted a systematic review on Scopus and Web of Science combining the four themes "value", "ES", "floodplain", and "location". We conducted a meta-analysis of the Danube floodplains' ES values with different sub-groups based on the ES classes (provisioning, regulating, and cultural) and implemented model selection based on the corrected Akaike Information Criterion. We selected 251 entries from 25 studies to set up with a PostgreSQL spatial database, which provides limitless possibilities to enrich the information on the study areas. We observed that the most important variables to describe ES values of DRB floodplains depend on the ES class, but in general the area proportions of water bodies and riparian landscapes are important, together with the valuation method and the chemical or ecological status of the corresponding river section. Finally, we provided two versions of unconditional benefit-transfer functions to evaluate provisioning, regulating, and cultural ES. This paper complements previously conducted meta-analyses to recognize significant characteristics to value ES and it is a valid basis to help determine the ES value of Danube floodplains.

Governance models for nature-based solutions: Seventeen cases from Germany.

Nature-based solutions (NBS) for mitigating climate change are gaining popularity. The number of NBS is increasing, but research gaps still exist at the governance level. The objectives of this paper are (i) to give an overview of the implemented NBS for flood risk management and mitigation in Germany, (ii) to identify governance models that are applied, and (iii) to explore the differences between these models. The results of a hierarchical clustering procedure and a qualitative analysis show that while no one-size-fits-all governance model exists, polycentricism is an important commonality between the projects. The study concludes by highlighting the need for further research on traditional governance model reconversion and paradigm changes. We expect the findings to identify what has worked in the past, as well as what is important for the implementation of NBS for flood risk management in future projects.

The knowledge transfer potential of online data pools on nature-based solutions.

Improving the adoption of Nature-based Solutions (NBS) requires learning from successes and failures. Knowledge derived from implemented cases helps to identify for instance drivers and barriers of NBS implementation, generates lessons learned, and supports their upscaling. Online data pools that catalogue information from NBS case studies may help scientists and practitioners to create this knowledge. The aim of this review is to assess the knowledge transfer potential of online data pools for implementing and upscaling NBS. For that, we compared 21 online data pools that report on NBS case studies in terms of topics, availability and quality of information on NBS. We found a high variability in quantity, type and quality of the information documented, hindering comparability and limiting knowledge transfer. Our results show that the most common knowledge provided was on actions undertaken on NBS, their outcomes, case study site descriptions, specific challenges and information on responsible entities and partners. Information on key attributes of NBS, such as on ecosystem processes and services as well as on governance and financing issues, was often omitted. The missing information however would be important for further comparative research to overcome implementation gaps for NBS. Based on the discussion of our findings we propose categories for a more efficient online data pool and give recommendations for further research on NBS.