A Quantitative Review of Natural Flood Management Research

Natural flood management (NFM), a subset of nature-based solutions (NBS) in catchment management, attempts to utilize and mimic natural processes in the landscape to reduce flood hazards, and it has been widely applied across Europe and other regions. Despite the wide use of NFM techniques, there is a lack of quantitative evidence for the effectiveness of NFM interventions in flood reduction. This paper examined 454 NFM relevant articles over the past 30 years, and the data they contain. Word frequency and cluster analyses showed changing trends and associations among nature-based flood mitigation research topics, including shifts from localized flood mitigation to catchment-wide flood management strategies, and from wood-related studies to a broader assessment of ecosystem services. Content analysis was conducted on literature directly related to NFM and NBS, revealing that research in large-scale catchments continues to be dominated by modeling approaches. While past reviews have suggested that increased catchment scale and rainfall intensity may diminish the effectiveness of NFM, we did not find strong empirical evidence (field monitoring and modeling) for this in our systematic review, although research at large catchment scale is still lacking. By assessing the confidence in NFM studies, the paper concludes that integrated understanding of a network of combined NFM interventions at a large catchment scale is necessary for future nature-based flood mitigation strategies.