Assessing the Hydrological Performance of Nature-Based Solutions Under Climate Change: Evidence, Challenges, and Future Directions

Abstract

This study aims to critically assess the hydrological performance of Nature-Based Solutions (NbS) under climate change, focusing on their capacity to reduce surface runoff and flood peaks, enhance infiltration and water retention, support groundwater recharge and low-flow conditions, and strengthen hydrological resilience. It further examines the climatic, spatial, methodological, economic, and institutional factors affecting NbS performance. A descriptive–analytical, critical, inductive, and comparative review approach was adopted to synthesize scientific evidence published between 2020 and 2025, with studies compared according to NbS type, climatic conditions, spatial scale, catchment characteristics, and hydrological performance indicators.

The findings indicate that NbS can provide significant hydrological benefits, particularly through runoff reduction, flood-peak attenuation, temporary water storage, delayed hydrological response, and enhanced infiltration. However, their effectiveness is conditional rather than universal and varies according to intervention type and location, soil and geological characteristics, catchment scale, antecedent moisture, rainfall magnitude, and climatic conditions. Evidence for flood mitigation is stronger and more consistent than that for drought mitigation, groundwater recharge, and sustained low-flow support. The review further demonstrates that locally observed benefits cannot be automatically extrapolated to catchment scale and that effectiveness under historical climate conditions does not necessarily guarantee robustness under future climatic extremes.

The study concludes that NbS assessment should shift from demonstrating hydrological effectiveness toward establishing climate-robust hydrological performance. Long-term monitoring, standardized performance indicators, validated hydrological models, multiple climate scenarios, explicit uncertainty analysis, and integrated economic and institutional assessments are therefore required. The findings further support context-specific comparison among NbS, grey infrastructure, and hybrid alternatives, with hybrid systems potentially offering a more reliable pathway where nature-based measures alone cannot manage residual climate risks. The study contributes to the literature by reframing the central question from whether NbS generally work to identifying which NbS remain effective, under which hydrological and climatic conditions, at what spatial scale, and with what degree of reliability under climate change.