Experts map potential Bay Area flood risks from El Niño: 'Things could be really, really bad'

NOVATO, Calif. (KGO) -- Parts of the Bay Area that have long faced flooding risks could see additional threats this winter as experts monitor a combination of factors including El Niño, sea level rise, king tides and warming ocean conditions.

Nonprofit leader Shannon Parkhurst is among those working to help residents prepare. While touring a Novato intersection that was submerged during the historic 1982 El Niño floods, she pointed to the area's vulnerability.

LIVE UPDATES: High tides continue to submerge parts of Bay Area with more flooding expected

"If you look around me, believe it or not, every single one of these houses that you're seeing have been underwater," Parkhurst said.

Parkhurst's nonprofit, the Lemon Aide Project, is helping neighbors prepare for potential flooding this winter. At the same time, climate scientists and planners around the Bay Area are assessing how severe flooding impacts could become.

Experts are monitoring several factors, including potentially wetter storms associated with El Niño, higher tides driven by sea level rise and king tide cycles, and Kelvin waves, which are masses of warm, expanding ocean water.

MORE: How El Niño is impacting flood advisory from high tides along California coast

"This happens when the water at the equator heats up and it pushes sort of a bulb of water up the California coast," said Dana Brechwald, assistant planning director for climate adaptation at the San Francisco Bay Conservation and Development Commission.

The commission has helped develop maps that project potential impacts from warming ocean temperatures and rising tides, helping establish baseline estimates for future flooding scenarios.

"We'll see about 12 inches of total additional water level due to thermal expansion," Brechwald said.

Brechwald said the maps are intended to help cities and counties plan for a range of scenarios while also providing residents with information about potential risks.

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Areas identified as particularly vulnerable include low-lying and levee-protected sections of the Marin County shoreline, parts of the Peninsula and South Bay communities such as Alviso, as well as significant stretches of the East Bay shoreline, including Alameda and Oakland Airport.

"You can see there's lots of overtopping at the airport and flooding in this residential neighborhood," Brechwald said.

For many residents in flood-prone areas, the king tides that caused flooding this month may offer a glimpse of how sea level rise and El Niño-driven storms could combine to create additional challenges this winter.

MORE: El Niño winter: Bay Area airports face flooding risk during holidays, research suggests

Organizations such as the Lemon Aide Project are encouraging residents to prepare emergency kits and evacuation plans ahead of potential flooding events.

"I want people to realize that things could be really, really bad," Parkhurst said.

Residents interested in exploring flood risks in their communities can access interactive maps through the San Francisco Bay Conservation and Development Commission website. Additional information about preparedness efforts is available through the Lemon Aide Project.