What are sponge cities?

What is a sponge city, and how can it combat the extreme flooding linked to fossil-fueled climate change?

Sponge cities are reimagined urban areas that imitate the natural water cycle. They prioritize water management through green infrastructure like parks, wetlands, rain gardens, bioswales, and green roofs. These nature-based designs aim to slow water, enhance ground absorption, and provide time for evaporation and transpiration.

Picture vibrant green parks for everyday use in dry weather, transforming into wetlands when it rains.

Vox associate video producer Halley Brown looks at the history and future of sustainable water urbanism, candidly reviews recent climate disasters, and talks with Dr. Charles Nilon, a wildlife ecologist and professor. Dr. Nilon provides insights into how cities designed to absorb water can better protect vital ecosystems—microbes, plants, insects, and animals—that humans depend on for food, medicine, and clean water and air. He explains:

“Urbanization changes habitat. So, when you build on a place, it removes vegetation and alters hydrology…”

“Cities have a big impact on what happens locally. Cities capture a significant number of plant and animal species, which are native, so that even in cities, there’s a significant amount of biodiversity, which means they can play a role in saving these local plant and animal species.

“The really important thing to think about is not so much how urbanization reduces biodiversity, but really how in cities you can conserve biodiversity.”

Watch these handpicked videos next:
• Do Cities Need More Green Roofs?
• What happens if you cut down all of a city’s trees?
• Why can’t engineers control rivers?
• Why are beavers and their super wild, messy wetlands essential?
• How can design make climate-resilient buildings?
• How do healthy ecosystems help protect us from droughts, heatwaves, and flooding?
• Shade vs Sun: Summer sidewalk temperatures in Tucson, Arizona

Also: What is groundwater?