Support for LAist comes from
We Explain L.A.
Stay Connected

Share This

Climate and Environment

LA Is At Greater Risk Of Flooding Than Previously Thought, Particularly In Black Communities

Bright fuschia cover a large part of North Long Beach to indicate flood waters that could rise above people's  heads. Cooler tones indicate lower flood risks.
New urban flood modeling by UCI shows a higher flood risk in the L.A.-area than previously reported.
(Courtesy Brett Sanders / UCI)
Before you read this story...
Dear reader, we're asking for your help to keep local reporting available for all. Your financial support keeps stories like this one free to read, instead of hidden behind paywalls. We believe when reliable local reporting is widely available, the entire community benefits. Thank you for investing in your neighborhood.

Los Angeles County is at higher risk of major flooding that previously thought, and Black communities throughout the county face the greatest risk.

How Was This Determined?

Using new modeling techniques, researchers at UC Irvine looked at what they call megacities — which include L.A. — to determine which residents would be most at risk should a flood occur.

"We did that by ... intersecting our modeling of the flood extent with the census data that shows where people live," said Brett F. Sanders, one of the study's co-authors and a UCI civil and environmental engineering professor.

Support for LAist comes from

They found that up to 874,000 people in the L.A.-area are at risk of damage from such a flood. Researchers report that a "100-year flood event in Los Angeles would expose more than 400,000 people to danger, and property damage could exceed $50 billion."

[Note: The map above shows places were water would reach above head level in bright pink.]

They compared the possible losses to major damages from severe hurricane, including Katrina in 2005 and Sandy in 2012.

2 Major Reasons: Rainfall And Water Channels

The reason so many people would be at risk is twofold.

  • First, the study marked the first time experts had modeled the potential impact of flooding caused by rainfall.
  • Second, some of the region's water channels don't have the capacity researchers thought they did.

"We knew there'd be a bigger exposure once we account for this rainfall type flooding," said Sanders, "but we were somewhat surprised at the scale ... there's a lot of people that would be exposed to a really rare flood in L.A. County."

Who Is At High Risk

Areas most likely to be affected include Compton, Carson and North Long Beach.

Sanders said he hopes this study will offer a way for city officials to create more equitable plans for flood safety.

Support for LAist comes from

"This can be thought of as an opportunity," he said. "We now can see where the risk is more robustly, and as we plan potential solutions, we can [ask] who benefits from these solutions and whether these solutions are going to be effective and fair."

What questions do you have about Southern California?