A new study showed that cities in a triangular form experience the least rainfall compared to square or circular cities. The study’s authors say the way wind and air interact with the shape of cities may be taken into account when designing future urban spaces that need to be more tolerant of the effects of the climate crisis.
Climate change, exacerbated by human activities, is causing an increasing number of extreme weather events, and the threat of flooding in cities is a growing concern. Cities are particularly vulnerable to events such as flash floods, as concrete piles do not have adequate drainage for heavy rains.
A study published in Earth’s Journal investigated whether the shape of a city affects weather, and the result was surprising. After realizing that some of Earth’s apparently wetter cities, such as London, were circular, the authors decided to investigate the effect of shape in more detail.
They looked at circular, square, and triangular cities (such as Dallas, New York, and Los Angeles, respectively) and compared the results of Weather Research and Forecast models and vortex simulations of air currents to see how shape could affect weather. They also compared this to out-of-town areas both inland and along the coastline.
The results showed that the shape of the city has a greater influence in cities in coastal areas because the airflow from the city interacts with the sea breeze. Circular cities with the most precipitation experienced 78.6 percent higher precipitation than triangular cities.
Overall, precipitation volume and intensity revealed the order of circular > square > triangular rain attracting shapes, with triangular cities generally experiencing the least and calmest types of rain.
The study authors write, “Given that climate change will intensify future precipitation hazards, global cities have invested substantial resources in studying and implementing diverse infrastructures as adaptation strategies.” “It demonstrates the important role of urban settlement in coastal areas. The circular city shape illustrates the potential risks of flooding with excessive precipitation and consequent.”
However, the authors acknowledge that their findings have limitations, and they say they hope to overcome some of these in their next work by investigating the effect of city shape under various wind conditions.
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