A bibliometric analysis and overview of the effectiveness of Nature-based Solutions in catchment scale flood mitigation

Riverine flooding is among the most destructive natural hazards globally, leading to economic losses and posing serious threats to lives and infrastructure. Nature-based Solutions (NbS) have emerged as sustainable alternatives to conventional flood management, offering environmental and societal benefits beyond flood protection. However, despite growing interest in NbS, their effectiveness for flood mitigation across different contexts and scales remains inadequately synthesised, hampering their widespread adoption. This systematic review of 141 academic and 7 grey literature documents analysed NbS that operate through three fundamental strategies - detaining floods, reducing flood energy, and diverting floodwater. These NbS interventions are grouped into four categories: managing catchment land cover, storing excess water, reviving alternative routes, and managing the floodplain, where each intervention utilises one or more of the three fundamental strategies for flood mitigation. The analysis reveals that catchment forest cover is the most studied intervention (19.6 %), followed by wetlands (14.3 %) and land use and land cover patterns (13.2 %). Well-designed NbS can significantly reduce flood peaks for frequent smaller events and offer valuable co-benefits. Combined approaches integrating multiple NbS types and conventional infrastructure show enhanced flood mitigation potential. The effectiveness of NbS varies depending upon the catchment's physical characteristics (size, slope, topography, geology), river networks, land use patterns, location of NbS implementation and event magnitude, along with climate condition. These findings advance the current understanding of NbS effectiveness and offer evidence-based guidance for implementing catchment-scale flood mitigation strategies, underscoring the importance of context-specific design.