California has faced multiple storms, with bringing record rainfall to the state. Now, heavy snowfall is impacting the Sierra Nevada mountains, with more precipitation on the horizon. Unfortunately, much of this rainwater goes to waste, frustrating conservationists and environmental advocates.
A Unique Approach in Los Angeles
Los Angeles is taking a different path as a sponge city, implementing infrastructure designed to capture urban water. The city managed to collect enough rainwater to supply over 100,000 households for an entire year. An atmospheric river brought 9 inches of rain to the city over three days—more than half of its typical annual total. As extreme rainfall events become more frequent due to climate change, the city’s water managers were prepared.
Transforming Urban Infrastructure
In recent years, LA has been evolving into a sponge city by replacing impermeable surfaces, like concrete, with permeable alternatives such as soil and vegetation. The city has also developed “spreading grounds” where water can accumulate and seep into the earth. LA captured 8.6 billion gallons of stormwater, enough to provide for 106,000 households for a year. Overall, the city has collected 14.7 billion gallons during the rainy season. Historically reliant on distant snowmelt and river water, LA is now focused on maximizing local water production.
Rethinking Urban Hydrology
Traditional urban planning has prioritized quickly draining rainwater to prevent flooding. However, with increasingly severe urban flooding worldwide, planners are now finding innovative ways to capture stormwater, viewing it as a resource rather than a burden. Michael Kiparsky, director of the Wheeler Water Institute at UC Berkeley, notes that the issue of urban hydrology stems from numerous small factors. Addressing this could involve many small solutions, akin to applying “a thousand Band-Aids.”
Enhancing Absorbency with Green Spaces
To make cities more absorbent, adding gardens and green areas that allow water to penetrate into aquifers is essential. Engineers are also transforming medians and roadside areas to absorb water that would typically flow into sewers and out to sea. As regions like the American West face increasing dryness, cities are seeking ways to produce more water locally, including recycling wastewater. Climate change exacerbates rainfall intensity; for every 1 degree Celsius of warming, the atmosphere can hold 6 to 7 percent more moisture, leading to wetter storms.
Innovative Water Capture Strategies
To take advantage of the rain, the Los Angeles Department of Water and Power (LADWP) has created large areas of permeable surfaces in the concrete landscape. Stormwater is directed into these spreading grounds, where it accumulates in dirt basins and gradually seeps into the aquifers, which can hold up to 28 billion gallons of water. After storms, the city continues to gather water in dams, diverting it into spreading grounds to minimize evaporation.
Mini Spreading Grounds and Community Benefits
On a smaller scale, LADWP is experimenting with converting parks into mini spreading grounds, allowing stormwater to soak into underground cisterns. Additionally, green spaces along roadways help mitigate neighborhood flooding by enhancing the area’s capacity to absorb stormwater. These green initiatives not only reduce flooding but also improve residents’ mental health and lower summer temperatures, combating the urban heat island effect.
A Broader Movement Toward Sustainability
Los Angeles is not alone in its efforts; cities like Pittsburgh are also implementing rain gardens and using permeable materials for necessary hard surfaces. Many municipalities are now charging property owners fees for excessive impermeable surfaces, incentivizing the adoption of permeable options like native plants and urban gardens.
The Future of Urban Water Management
The traditional approach to stormwater management is increasingly inadequate and poses risks as climate change intensifies storms. LA’s innovative strategies illustrate that there is a more sustainable, beautiful, and less oppressive way to manage urban water resources.
Reference
1.Los Angeles Just Proved How Spongy a City Can Be
https://www.wired.com/story/los-angeles-just-proved-how-spongy-a-city-can-be/
- Los Angeles sponge city infrastructure paying off amid stormy 2024
https://www.krwg.org/2024-03-05/los-angeles-sponge-city-infrastructure-paying-off-amid-stormy-2024
