Leaky dams are an increasingly popular natural flood management measure, yet their impacts on flood peak magnitude have not yet been empirically quantified for a range of event types and magnitudes, even at the stream scale. In this study, the novel application of a transfer function noise modelling approach to empirical Before-After-Control-Impact stage data from an upland catchment allowed leaky dam effectiveness in reducing flood peak magnitude to be quantified. Flood peak stage and discharge magnitude changes were assessed from empirical data for 50 single and multi-peaked high flow events with return periods ranging from less than one year to six years. Overall, event peak magnitude was significantly reduced following the installation of eight leaky dams on the impact stream. Effectiveness was highly variable, but on average, flood peak magnitude was reduced by 10% for events with a return period up to one year. Some of the variability was explained by the size of the event and whether it was a single or multi-peaked event. This finding emphasises the need to manage expectations by considering both a range of event magnitudes and types when designing or assessing leaky dam natural flood management schemes.

This study reviews the use of large wood in stream restoration across 50 projects in Germany and Austria, highlighting its potential to improve hydromorphological and ecological conditions. Results show that many projects use wood volumes and structures below natural levels, often placing wood parallel to flow, limiting effectiveness. Only 58% of projects monitored restoration success. Key findings include the importance of watershed-scale evaluation, the benefits of mimicking natural wood, and variable effects depending on stream size and hydrology. Fixed wood (‘hard engineering’) dominates, but non-fixed (‘soft engineering’) methods are more cost-effective and create more natural features. The authors recommend increasing wood quantity and size, improving monitoring, and prioritising passive restoration—restoring natural wood recruitment processes—over active placement as a sustainable long-term strategy.

Leaky dams have become essential nature-based solutions for flood management, providing sustainable alternatives to traditional engineered flood control methods. This review delves into the mechanisms by which leaky dams operate, including the regulation of water flow through velocity reduction and distribution across floodplains, effective sediment trapping and soil quality enhancement, and the facilitation of groundwater recharge and water table stabilization. These structures not only mitigate peak flood flows and reduce erosion but also contribute to enhanced biodiversity by creating diverse aquatic habitats and maintaining ecological connectivity. The effectiveness of leaky dams is assessed through various performance metrics, demonstrating significant reductions in peak flows, improved sediment management, and increased groundwater levels, which collectively enhance ecosystem resilience and water quality. However, the implementation of leaky dams presents several technical challenges, such as design complexity, hydrological variability, maintenance requirements, and socio-economic factors like land use conflicts and economic viability. Additionally, while leaky dams offer numerous environmental benefits, potential negative impacts include habitat disruption, sediment accumulation, and alterations in water quality, which necessitate careful planning and adaptive management strategies. Emerging trends in leaky dam development focus on the integration of smart technologies, such as real-time monitoring systems and artificial intelligence, to optimize performance and resilience against climate-induced extreme weather events. Advances in modeling and monitoring technologies are facilitating the effective design and implementation of leaky dam networks, promoting their incorporation into comprehensive watershed management frameworks. This review highlights the significant potential of leaky dams as integral components of sustainable flood management systems, advocating for their broader adoption alongside conventional engineering solutions to achieve resilient and ecologically balanced water management.

The International Union for Conservation of Nature (IUCN) defines Nature-Based Solutions (NBSs) as actions that protect, manage, and restore ecosystems to address societal challenges like climate change, while benefiting both biodiversity and human wellbeing. In the Aa of Weerijs catchment, where historic engineering drained excess water, emerging water shortages now call for new NBSs aimed at retaining water. Projects such as Co-adapt and Pro-Water have identified and mapped various NBS options, including installing small natural barriers in streams to slow water flow, reduce erosion, and enhance infiltration. These solutions are modelled and targeted to specific locations to improve climate adaptation strategies in the region.

This research explores the potential of reintroduced Eurasian beavers (Castor fiber) to contribute to natural flood management (NFM) in the Adur catchment, Sussex. By characterising beaver dam structures and identifying suitable dam-building locations using GIS and hydraulic modelling, the study simulated dam impacts on flood stages and inundation. Results showed that 84% of watercourses were suitable for dam construction, with dam presence increasing upstream water levels and reducing downstream flood extent. The findings support using beaver dams as a nature-based solution for flood risk mitigation and offer a modelling framework to assess potential impacts for future beaver reintroductions.

The Eurasian beaver (Castor fiber) has begun to naturally recolonise parts of Italy after centuries of absence, with populations currently small but expanding. Their dam-building activities enhance ecosystem functions by improving water retention, reducing erosion, and increasing biodiversity. While some human–beaver conflicts have arisen, such as minor flooding and crop damage, these are generally manageable using mitigation measures proven elsewhere in Europe. The beaver’s return highlights both the species’ ecological benefits and the need for coordinated conservation efforts, monitoring, and public awareness to ensure successful coexistence.

Landscape rewilding has the potential to help mitigate hydrological extremes by allowing natural processes to function. Our systematic review assessed the evidence base for rewilding-driven mitigation of high and low flows. The review uncovers a lack of research directly addressing rewilding, but highlights research in analogue contexts which can, with caution, indicate the nature of change. There is a lack of before-after studies that enable deeper examination of temporal trajectories and legacy effects, and a lack of research on the scrub and shrubland habitats common in rewilding projects. Over twice as much evidence is available for high flows compared to low flows, and fewer than one third of studies address high and low flows simultaneously, limiting our understanding of co-benefits and contrasting effects. Flow magnitude variables are better represented within the literature than flow timing variables, and there is greater emphasis on modeling for high flows, and on direct measurement for low flows. Most high flow studies report a mitigating effect, but with variability in the magnitude of effect, and some exceptions. The nature of change for low flows is more complex and suggests a higher potential for increased low flow risks associated with certain trajectories but is based on a very narrow evidence base. We recommend that future research aims to: capture effects on both high and low flow extremes for a given type of change; analyze both magnitude and timing characteristics of flow extremes; and examine temporal trajectories (before and after data) ideally using a full before-after-control-impact design.

The article highlights the LIFE BEAVER project in Slovenia and Croatia, which aims to manage the return of European beavers and reduce human–wildlife conflict. It showcases how practical tools like water-level regulators and community workshops help mitigate issues while preserving ecological benefits such as flood control and biodiversity. The project also evaluates ecosystem service values to guide future land and water policies.

Beavers have the ability to modify ecosystems profoundly to meet their ecological needs, with significant associated hydrological, geomorphological, ecological, and societal impacts. To bring together understanding of the role that beavers may play in the management of water resources, freshwater, and terrestrial ecosystems, this article reviews the state-of-the-art scientific understanding of the beaver as the quintessential ecosystem engineer. This review has a European focus but examines key research considering both Castor fiber—the Eurasian beaver and Castor canadensis—its North American counterpart. In recent decades species reintroductions across Europe, concurrent with natural expansion of refugia populations has led to the return of C. fiber to much of its European range with recent reviews estimating that the C. fiber population in Europe numbers over 1.5 million individuals. As such, there is an increasing need for understanding of the impacts of beaver in intensively populated and managed, contemporary European landscapes. This review summarizes how beaver impact: (a) ecosystem structure and geomorphology, (b) hydrology and water resources, (c) water quality, (d) freshwater ecology, and (e) humans and society. It concludes by examining future considerations that may need to be resolved as beavers further expand in the northern hemisphere with an emphasis upon the ecosystem services that they can provide and the associated management that will be necessary to maximize the benefits and minimize conflicts.

The questions we address in the present aricle are the following: (i) whether (extreme)river floods can be prevented or seriously mitigated by the introduction of beavers inthe wild, and (ii) for which river catchments does flood mitigation by beaver activity(not) work? By using the concept of flood-excess volume (FEV) for four rivers in theUK, in the context of five (extreme) UK flood events in the last two decades, we showthat even a 10% flood reduction of the FEV, using beaver colonies and beaver dams,requires hundreds of such colonies per river catchment. Given the high number of beavercolonies and dams required for mitigation, we conclude/demonstrate that serious floodmitigation by massive introduction of beaver colonies is completely unrealistic, in starkcontrast to statements made in scientific literature and in the media. Furthermore, FEVis valuable beyond its utility as a tool in analysing the efficacy of beaver dams as floodprotection: it is demonstrated to be a useful tool for assessing in an easy-to-understandway a variety of flood-mitigation measures, including analysing the scalability of localflood-mitigation measures for overall catchment needs.