Nature-based solutions for flood mitigation: a systematic review of evidence, performance mechanisms, and implementation conditions

Abstract

Flooding is one of the most significant natural hazards worldwide, with risks intensifying due to climate change, rapid urbanisation, and land-use transformation. In response to the limitations of conventional grey infrastructure, Nature-Based Solutions (NBS) have gained increasing attention as sustainable strategies for flood risk management. This study presents a systematic literature review examining how NBS are applied and evaluated in flood mitigation research. Peer-reviewed studies published between 2016 and 2026 were identified through structured searches in Scopus and Web of Science, guided by the PRISMA framework and a SPIDER-based review structure. Following duplicate removal and eligibility screening, 136 studies were retained for analysis. Evidence was synthesised using structured coding, descriptive statistics, and thematic synthesis to examine NBS types, flood hazard contexts, performance indicators, hydrological mechanisms, co-benefits, and governance conditions. The findings show that urban green infrastructure and low-impact development measures dominate the literature, particularly for pluvial flooding, while wetland restoration and river restoration approaches are more commonly applied to riverine flood management. Key hydrological mechanisms include increased infiltration, floodwater storage, hydraulic roughness, and hydrograph desynchronisation. However, the evidence base remains dominated by modelling approaches, with limited long-term empirical monitoring of implemented interventions. This review contributes by linking NBS types, flood hazards, performance evaluation metrics, and implementation conditions. The findings highlight the need for stronger empirical evidence, standardised hydrological indicators, and integrated grey–green infrastructure approaches to support the wider adoption of NBS in sustainable flood risk management.