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

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.

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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.

"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."