El Nino is delivering a forceful lesson in applied geology to California. Inch by inch, the coastline is washing away, in some cases taking houses with it.
Eighty-six percent of the 1,100-mile coast is crumbling because of storm and wave action, high tides, strong winds and urban development that accelerates bluff erosion.
A recent study by the Institute of Marine Sciences at University of California, Santa Cruz, found that coastal erosion makes the state, on average, 6 to 12 inches skinnier every year.
“But it’s a very episodic process. In an El Nino year, we can lose 4 to 10 feet. … One big winter could do it for 30 feet,” said institute director Gary Griggs, a professor of earth sciences at UC-Santa Cruz.
El Nino is the name given to the unusual warming of waters in the Pacific Ocean that affects global wind and temperature patterns. Along the West Coast this year, El Nino is blamed for a series of devastating rainstorms.
Even in dry years, wave action, tides, wind and rain gnaw a few inches from cliff faces.
Since the 1976 passage of the state’s Coastal Act, the California Coastal Commission and local jurisdictions have been asking oceanfront developers to prove that building sites will not be susceptible to erosion.
In San Mateo County, planning administrator Terry Burnes said builders now have to furnish technical reports showing the sites “will be intact beyond a 50-year erosion line.”
As a consequence, “we haven’t really had a lot of oceanfront development since 1980, only 10 or 15 homes,” Burnes said.
“A majority of the problems you see occurring now predate the Coastal Act,” said Brian Baird, ocean program manager for the California Resources Agency.
Development accelerates coastal bluff erosion. “The more you pave streets, the more you put down roofs and sidewalks, the more runoff there is,” Griggs said. “It soaks the bluffs, and the wetter they are, the weaker they are. … Ornamental plants require huge amounts of watering, and that also leads to a weakening of the bluffs.”
In “California Ocean Resources: An Agenda for the Future,” the resources agency last year proposed an aggressive strategy to reduce the damaging effects of coastal erosion - in large part because it calculated that beaches and other coastal uses are a $12 billion-a-year asset for the state.
MEMO: This sidebar appeared with the story: TAKING STEPS In San Mateo County, planning administrator Terry Burnes said builders now have to furnish technical reports showing the sites “will be intact beyond a 50-year erosion line.”