California prepares for water rise due to Kelvin wave — The Guardian
Communities in California are preparing for the approach of a Kelvin wave — a large underwater band of warm water that could raise water levels along the state’s coast by about one foot, or 30 cm. The wave is approaching Southern California and is expected to reach the San Francisco Bay Area in early October, The Guardian reports.
How the Kelvin wave works
Unlike an ordinary ocean wave, a Kelvin wave does not rise up or break against the shore. It raises tides from beneath the water’s surface and creates conditions in which elevated sea levels can persist longer. The phenomenon is linked to El Niño conditions: warm water moves across the Pacific Ocean, reaches the coast of South America, and then travels north.
Mike Jacox, a research oceanographer at the National Marine Fisheries Service, noted that Kelvin waves are not always dangerous on their own. However, their impact may intensify during very high tides or storm surges. Such a combination can lead to flooding of beaches, streets, homes and businesses, as well as coastal erosion.
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Preparing for winter storms
Jonathan Warrick, a research geologist at the U.S. Geological Survey, warned that particular attention should be paid to January, February and March, when the region usually experiences its largest storms, waves and tides. The year’s highest tides in some areas of California are forecast for November and December.
Climatologist Daniel Swain said that coastal flooding is virtually inevitable. He recalled the winter of 1997–1998, when powerful storms caused extensive coastal erosion, landslides, road damage, levee breaches, and flooding of thousands of homes and businesses. At the time, 21 of the state’s 58 counties were declared disaster areas.
In the San Francisco Bay Area, sandbags are already being delivered, drainage systems and culverts are being cleared, infrastructure conditions are being assessed, and temporary flood barriers are being installed. Nick Brubaker, resilience manager at the Marin County Office of Emergency Management, noted that rising sea levels could complicate the drainage of water from overflowing creeks and streams.
