Photo of Pacifica Pier.
earth, environment

A Coast Process

All of California may not one day fall into the ocean, but right now, parts of it do.

Erosion occurs all along the coast. Every ocean wave pounds on the bluffs and scours the beaches.

Pictured above is the Pacifica Municipal Pier.

It’s shaped like an “L” — you can see that it makes a right turn toward the end. It’s 1,140 feet long. When you’re on the pier, you can look far north or south, depending on the fog. Here’s a view to the north on a clear, windy day.

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Along this stretch of Pacifica, there’s a seawall protecting the buildings along the coast. If not for this kind of coastal “armoring” as it’s generally called, the waves you see in this photo would tear up the cliff and the houses would fall in. The wall itself needs some protecting, which is why there are so many rocks—called riprap—piled at the base.

Something that’s missing here is a beach.

There’s a trade-off involved when you armor a coast, and what tends to be lost are things like beaches (by interrupting replenishment from sediments upstream) and coastal access. I learned much of this first-hand, and got a Pacifica tour in the process, from coastal experts Bob Battalio and David Revell at Philip Williams & Associates.

I interviewed them for a feature that’s just come out for Terrain Magazine. The story, A Rising Tide, looks at the potential effects of sea-level rise in Northern California. What’s in store? Increased erosion along some parts of the California coast–which will probably inspire even more armoring–and in some low-lying areas, increased flooding risk. The single hardest hit area? San Francisco Bay.

Here, for example, some of the new flooding risks by 2100 at predicted sea-level-rise rates along San Francisco’s Embarcadero, the baseball park, Mission Bay, and Treasure Island.

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You can download the whole report on the Pacific Institute’s web site. If you want to see the technical report covering coastal erosion created by Revell, Battalio, and their colleagues, you can download it from the PWA site.

My thanks to all I talked to for this story. In particular, Battalio and Revell were articulate, enthusiastic, and knowledgeable—in other words, perfect sources. Revell drove a truck and Battalio a mini-van to our meeting in Pacifica; in back were more than enough surfboards to go around.

Story: A RISING TIDE: As sea level creeps higher, what’s next for California’s coasts?
Terrain Magazine
Summer 2009

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