When Los Angeles received 9 inches of rain in three days this month, some neighborhoods experienced destructive flooding and mudslides, garnering much of the media’s attention. But, as Matt Simon points out in an article in Wired, the city also collected 8.6 billion gallons of stormwater, enough to cover the needs of over 100,000 households for a full year.
This is thanks to new green infrastructure designed to be ‘spongy’ rather than direct stormwater to the ocean, as it did in the past. Los Angeles has built new dams and spreading grounds that capture water and direct it into underground aquifers for future use.
The trick to making a city more absorbent is to add more gardens and other green spaces that allow water to percolate into underlying aquifers—porous subterranean materials that can hold water—which a city can then draw from in times of need. Engineers are also greening up medians and roadside areas to soak up the water that’d normally rush off streets, into sewers, and eventually out to sea.
In addition to helping to refill local aquifers, the new green spaces can improve the mental and physical health of residents. “Plants here also “sweat,” cooling the area and beating back the urban heat island effect—the tendency for concrete to absorb solar energy and slowly release it at night.”