Climate

Kiley Price, Inside Climate News -   From sprawling skyscrapers to busy highways, many of the characteristics that make major cities so iconic also put them at risk of severe flooding. When a rainstorm hits, the mostly impermeable materials used to construct roads and sidewalks—such as concrete and asphalt—often wick water into other streets or storm drains. 

“We superimposed what we wanted onto the landscape … and then by doing that, we essentially sealed the surface of the landscape,” Franco Montalto, a civil engineer at Drexel University, told me. 

While these drainage systems may have held up to storms when they were first constructed, many aren’t equipped to withstand the increasingly severe rainfall brought by climate change, he added. 

In New York City, for example, roughly 60 percent of the sewers are part of a centuries-old combined system where stormwater and sewage run through the same pipes to wastewater treatment plants. That means extreme rain events often trigger sewage overflows into key waterways, as my colleague Lauren Dalban reported in 2024. As an NYC resident, I’ve seen (and smelled) this firsthand.