Coastal Kelvin Wave Threatens Southern California with Rising Seas and Erosion
Southern California cities are grappling with flood damage and shoreline loss as a coastally trapped Kelvin wave approaches, potentially adding several inches of sea level.
Recent south-swell storms linked to Hurricane Marie have flooded homes and eroded coastlines across Southern California, prompting emergency declarations in Laguna Beach, Dana Point and Carlsbad. Orange County officials activated their emergency operations center as two cities declared local emergencies, and Metrolink highlighted severe erosion threatening rail tracks in San Clemente. Researchers explain that a coastally trapped Kelvin wave, now traveling along Mexico’s western shore, is expected to reach Southern California in early October, potentially raising sea levels by six to twelve inches for months.
The wave follows a strong El Niño, which forecasters assess has a 75% chance of being the strongest since 1950 and a 98% chance of being “very strong” through December. Experts say the added water height could exacerbate flooding and beach loss, especially when combined with upcoming storms, threatening coastal infrastructure and sand-replenishment projects.
Why it matters
The wave could intensify flooding and erosion, endangering homes, infrastructure and beach restoration efforts along the densely populated California coast.
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