This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A new study reveals a troubling consequence of climate change: Even as rainfall decreases, cities could face increasingly severe flooding. The study was led by Ph.D. student Raz Nussbaum and co-authored by Dr.
Moshe Armon and supervised by professor Efrat Morin from the Hebrew University of Jerusalem. Published in the Journal of Hydrology, the research first analyzed projections from 32 global climate models under a high-emissions scenario, finding that 26% of the world's urban areas, currently home to approximately 1.5 billion people, are projected to experience declining overall precipitation alongside intensifying extreme rainfall by the end of the century. The researchers then asked what this combination means for urban floods, a question that had remained largely unexplored.
They found a two-sided pattern: Weak runoff events become weaker, while the strongest ones, which are most likely to cause flooding, become even stronger. Moreover, urban development can amplify this phenomenon, leaving densely populated cities particularly vulnerable. "Climate change is not simply making cities wetter or drier.
It is fundamentally changing how rain falls," said Nussbaum. "Some regions are expected to receive less rain overall, but in shorter, more intense bursts. Our findings suggest that in these regions, the most extreme floods could become even more extreme.
Urban flood protection will therefore need to be rethought, and not only because of climate change. Population growth and urban densification are expanding impervious surfaces, which intensify runoff, while exposing larger populations to flood risk." To investigate this phenomenon, the researchers combined global climate projections with detailed rainfall and urban drainage simulations, focusing on the Nahal Ra'anana catchment in central Israel. Using more than 5,300 simulations of heavy rainfall events under different climate and urbanization scenarios, the researchers examined how future storms could affect runoff in urban environments.
Their findings revealed that future storms in the eastern Mediterranean are expected to become more concentrated in both space and time. In the Ra'anana study area, maximum rainfall intensity over a 10-minute period increased by approximately 20% in the future climate simulations, even as longer-duration rainfall and total precipitation declined. This creates a dangerous combination: Rainfall may become less widespread, but when intense storms strike urban areas, they can generate powerful runoff.
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