Tropical flash floods are becoming more frequent, widespread, and destructive with global warming, yet their risks remain severely underestimated. In tropical regions, flash floods often escalate into regional disasters within a short timeframe due to intense convective storms, vulnerable land surface conditions (such as disorderly urbanization and steep slope occupation), and lagging early warning systems. Brazil's recent history of extreme flood events serves as stark evidence. Yet most global flood models rely on temperate region data, leaving them inadequate for simulating tropical flash floods. Placing flash flood research at the core of Earth system science and climate adaptation—through improved modeling, enhanced monitoring, multi-hazard early warning systems, and community engagement—is essential to confront this escalating climate risk.
Tropical flash floods rank among the fastest-growing and deadliest hydro-meteorological disasters. In tropical regions, they are typically triggered by intense convective rainfall exceeding 100 mm/hour over short periods. Combined with vulnerable land use practices—such as deforestation, steep slope occupation, and uncontrolled urban sprawl—this leads to a sharp increase in surface runoff and reduced soil infiltration capacity, triggering flash floods and cascading disasters like landslides and infrastructure damage. Extreme flood events in Petrópolis (Brazil, 2022), Recife (Brazil, 2022), and Rio Grande do Sul (Brazil, 2023–2024) highlight their unpredictability and immense destructive power.
However, current global flood models primarily rely on data from temperate regions like Europe and North America, exhibiting insufficient simulation capabilities for rapid, localized intense convective storms in tropical areas. This results in significant biases in risk assessments. To enhance model applicability in tropical regions, the authors propose integrating high-resolution satellite rainfall data, strengthening ground-based hydrometeorological monitoring networks, and developing coupled climate-hydrological models capable of simulating sub-hourly processes.
As global temperatures rise, extreme rainfall events are intensifying in both tropical and temperate zones. The dynamic characteristics of tropical flash floods are gradually expanding into temperate regions, blurring the boundary between the two. Climate warming not only amplifies convective heavy rainfall but also increases its complex interactions with saturated soils, steep topography, and vulnerable land uses, further exacerbating flood risks and impacts.
To effectively address this challenge, early warning systems must integrate high-resolution nowcasting, real-time hydrological modeling, and societal vulnerability assessments. Community engagement is essential to enhance the actionability of warning information. Concurrently, policymakers and urban planners should strengthen land-use regulations, upgrade drainage and housing infrastructure, and place flash floods at the core of global climate adaptation agendas. This is crucial to mitigate their immediate and disproportionate threats to billions worldwide.
Sources:
nature geoscience
https://www.nature.com/articles/s41561-025-01844-8 .
Provided by the IKCEST Disaster Risk Reduction Knowledge Service System
Comment list ( 0 )
