Nature-based Solutions (NbS) have emerged as a sustainable approach to managing flood risks by enhancing natural water retention and reducing surface runoff in urban areas. As climate change and rapid urbanization exacerbate flood hazards, optimizing the spatial deployment of NbS is crucial for improving urban resilience and mitigating flood impacts. This study presents a comprehensive optimization framework for the spatial allocation of fourteen different NbS types aimed at mitigating urban flood risks in Gdańsk, Poland. Leveraging a genetic algorithm alongside the Urban Flood Risk Mitigation (UFRM) model of the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) software suite, we identified areas of the city most vulnerable to pluvial flooding and optimized NbS placement to maximize water retention and reduce runoff. The optimization process balanced multiple objectives, including minimizing implementation costs and maximizing water retention capacity, ensuring that the solutions are both economically feasible and environmentally effective. Three distinct scenarios were proposed: a cost-effective solution, a high-retention solution, and a balanced solution, offering urban planners a range of strategies to address flood risks based on their specific priorities and constraints. Results demonstrated considerable variations in water retention effectiveness across different NbS configurations, with denser urban regions showing the most significant improvements from targeted interventions. The optimized placement of NbS resulted in estimated total water retention improvement of approximately 15.5 % for the best solution considered. These findings provide valuable insights for integrating NbS into urban flood management strategies, enhancing citywide resilience, sustainability, and long-term flood mitigation.

Climate change has increased the frequency of extreme weather events, challenging traditional flood risk assessments. New methods, like InVEST’s urban flood risk mitigation model (UFRM), are crucial for assessing flood-prone areas, especially those vulnerable to pluvial flooding. This systematic review examines the utilization and limitations of the UFRM model for identifying flood-prone areas and designing adaptation plans in response to climate change, based on research articles published between 2019 and 2024. The articles were identified through Scinapse and Google Scholar using predefined criteria, including relevance to UFRM applications and publication within the specified timeframe. An analysis of the 21 selected papers using bibliometric techniques reveals geographic concentrations of the case studies that utilized the UFRM model primarily in Italy, Turkey, China, and the United States, with notable research gaps in Central Europe. The journal publication trends highlight the prominence of certain journals, such as the Journal of Land. A network analysis using VOSviewer identifies thematic clusters aligned with the UFRM research areas, including Urban Planning and Nature-Based Solutions (NBSs), Urbanization and Sustainable Development, the Economic and Social Effects of Flood Mitigation, Adaptation and Risk Management, and Resilience and Vulnerability. This review contributes to gaining a deeper understanding of the research landscape regarding the utilization of the UFRM model and provides recommendations for advancing sustainable and resilient urban development practices. The review was not preregistered in a formal registry. The finding reveals that integrating automation and optimization tools to suggest different solutions for problematic nodes in urban areas is crucial for addressing multiple issues simultaneously and optimizing adaptation plans effectively.

Nature-based solutions (NbS) are increasingly promoted for climate adaptation to compound hazards, but systematic evidence of their effectiveness is still scarce. We address this gap with a systematic review of 38 studies. Each study was sorted by what its measurement design can support, not by what its authors claim. This produced four groups. Direct studies attribute a measured hazard reduction to the intervention, proxy studies infer protection from ecosystem condition, prioritization studies map suitable locations without estimating performance, and qualitative studies describe effectiveness without measuring it. We detect trends in geographic distribution, hazard combinations, intervention types, methodological approaches, and strength of evidence. Six studies directly measured attributable hazard reduction, and the remaining 32 studies fell into the proxy, prioritization, or qualitative classes, none of which can separate an ecosystem that buffers a hazard from one that receives it. The evidence concentrates on coastal flooding, with urban heat second. The most common hazard combination, compound drought and heat, yielded no direct evidence of hazard reduction, and only one of the five studies addressing cascading hazards did so. Research priorities include direct assessment of vegetation-based NbS under compound drought and heat, attributable measurements for cascading hazards, and long-term monitoring of hazard outcomes. As NbS are scaled, confidence in them should be scaled with the strength of the evidence base.

Urban flooding is an increasing environmental hazard. It is intensified by land take and the conversion of natural landscapes into sealed urban surfaces. These changes reduce stormwater management capacity. The hydrological processes driving flooding are well understood. However, the impact of land-use transitions on flood sensitivity is less explored, especially in different urban contexts and integrating land take into flood risk management remains a major challenge. In response to this gap, this study analyses land use changes in Gdańsk (Poland), Milan (Italy), Ghent (Belgium), and Oslo (Norway) between 2012 and 2018. It examines their relationship with urban water accumulation using the InVEST Urban Stormwater Retention Model. The study introduces the Water Accumulation Sensitivity Index (WASI) and the Normalised Water Accumulation Sensitivity Index (NWASI), which provide a quantitative framework for assessing urban sensitivity to water accumulation. The findings show how local land take patterns influence flood risk. Comparative results show that Gdańsk and Milan exhibit increased accumulated water linked to conventional residential and industrial expansion. Oslo displays high hydrological sensitivity despite minimal land take, due to forest and agricultural conversions. Ghent demonstrates that land take directed toward green infrastructure can stabilize or even reduce water accumulation. WASI and NWASI enable managers to identify high-risk areas for targeted interventions, such as green infrastructure related measures or restrictions on impervious surface development. This research supports evidence-based land use policies to balance urban growth with flood resilience and to improve environmental management and climate adaptation.