El Niño threatens 6 regions of California, see danger zones

California’s coastline is bracing for a double whammy this winter, and six places, from San Luis Obispo to Humboldt Bay, face an increased risk of flooding and erosion.

These key geographic hotspots are likely to experience beach loss, damage to shoreline properties, cliff instability, and temporary or permanent destruction of infrastructure, according to a new study released by UC Davis.

According to the study, these extreme weather conditions are due to a foot-long rise in sea levels due to climate change, as well as what could be the strongest El Niño on record.

The six areas facing the greatest risks of flooding and erosion are:

1. San Luis Obispo County: Public beaches and roads in Avila Beach and Pismo Beach are facing severe damage from erosion and waves.
2. Coastline of Monterey and Santa Cruz: The Elkhorn Slough area, Moss Landing, local roads, agricultural fields and waterfront homes in Santa Cruz are vulnerable to severe flooding.
3. South San Francisco Bay: Residential areas, local roads, marshes, and major transportation hubs, including San Francisco International Airport, the East Bay marshes, and the eastern approach to the Bay Bridge along I-80, face elevated flood risks.
4. Marin and North Bay arteries: US-101 in Corte Madera, residential areas in San Rafael, and critical segments of Highway 37 near Novato Creek, the Petaluma River, and Mare Island are highly susceptible to saltwater flooding.
5. Stinson Beach: Beachfront homes, local roads and beach infrastructure are directly threatened by storm surges and coastal erosion.
6. Humboldt Bay: Surrounding agricultural fields, local roads, US-101 corridors, and low-lying marshes face great vulnerability due to high tides and runoff.

“All of the problems we see today were predicted years ago and we should not be surprised when they start to occur,” Fraser M. Shilling, director of the Road Ecology Center at UC Davis, said in the study.

A “Kelvin wave” in the eastern Pacific, coupled with storm tracks that continually push water inland, has already exposed Southern California to powerful waves, high tides and historic flooding, the study found.

Researchers warn that the threat is far from theoretical. During the winter of 2019, atmospheric river storms caused coastal waters to rise nearly 10 inches, closing Highway 37 in North Bay during an otherwise weak El Niño, the study notes.

“It is possible that flooding of Southern California beaches will cause irreversible damage to the beaches of Long Beach and the Newport Peninsula that even extensive riprap and increased sand will not be able to resolve,” Shilling added.

Experts warn that the accumulation of these high sea base levels with open coastal swells and inland runoff will trigger severe flooding and accelerated erosion across the state.

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