In LA, drought and fire are considered the biggest climate problems. But Angelenos should also worry about flooding, according to a new study from UC Irvine. Researchers found that hundreds of thousands of LA County residents could be inundated by at least a foot of flood water — should a once-in-a-100-year storm hit the area.
One of the researchers is Brett Sanders, a professor of civil and environmental engineering at UC Irvine.
He describes such an event: “Imagine … it rains every day for a month. And so when we get an intense downpour of rain, then there's nowhere for the water to go. The channels [like the LA River or the San Gabriel River] are undersized to contain it. And we see flooding across urban areas, floodwaters spilling over channels, and then collecting into lowland areas in the region.”
He explains that deep flooding is when water rises above doorsteps, saturates the first floor of a house, potentially shuts down the electrical system, and ruins the drywall.
The area particularly vulnerable to deep flooding starts in Long Beach and moves north along the LA River into Bell Gardens, Sanders identifies. That part of LA County was historically composed of freshwater marshlands, where the LA River and San Gabriel River would have wandered on their way to the ocean. He says houses there lie below the height of levees that are meant to protect them.
He adds, “[Our research showed] deeper flooding was associated with communities that had higher Black populations.”
How to prepare for or prevent serious flooding? Sanders says city departments can update their building codes and renovate properties at higher elevations. But the biggest long-term response is to rebuild LA’s flood infrastructure, which is aging.
“I think the future for Southern California … involves a wider channel … to create more space for water and more space for water conservation.”