Volume 3, Issue 3

Rapid urbanization and intensifying rainfall are overwhelming drainage systems in tropical cities, where conventional gray infrastructure is costly to expand and often poorly maintained. Nature-based solutions such as bioretention systems, green roofs, constructed wetlands, permeable pavements and restored urban streams are promoted as complements to pipes and channels, but most design guidance and performance data come from temperate climates. This review synthesizes evidence on the hydrological and water quality performance of nature-based stormwater solutions in tropical and subtropical cities, identifies the design adaptations that tropical conditions require and examines the barriers to their wider adoption. Field studies show that well-designed systems can substantially reduce runoff volumes and peak flows for frequent storms and remove most suspended solids, but their effect diminishes during the intense, long-duration events that cause the most damage. High rainfall intensity, year-round biological activity, deeply weathered soils, mosquito control requirements and dense informal settlement call for larger storage volumes, robust vegetation, rapid drawdown and integration with community-scale drainage. Implementation is constrained less by technical feasibility than by fragmented institutional responsibilities, limited maintenance funding, land scarcity and a lack of locally calibrated design standards. We propose priorities for long-term monitoring, design guidance and financing, and argue that tropical cities should plan nature-based solutions as part of hybrid green–gray systems sized for local rainfall regimes.