Expert warns barriers cause beach to recede.

Byline: Winston Ross The Register-Guard

NEWPORT - It's time to start letting Oregon Coast buildings fall into the sea.

Either that or move the structures back from the bluffs, otherwise the Pacific Ocean's powerful waves will make the decision for us, said a Duke University expert on beach erosion who spoke at a conference in Newport on Saturday.

Earth and ocean sciences professor Orrin Pilkey was the keynote speaker at this year's Coast Conference, a forum on ocean policy sponsored by the Oregon Shores Conservation Coalition.

He came to discuss the worldwide effects of human attempts to control coastal erosion - the systematic lapping away of coastlines by incessant ocean waves.

Pilkey showed a series of slides during his presentation, many of them before-and-after shots of buildings that had slipped into the sea or been moved inland. But he also showed photographs of the alternative - attempts to halt the seas' advance.

In some places, homeowners, businesses and governments install artificial structures along beaches, known as seawalls. They can be built of concrete or some other material, such as walls of rocks, known as riprap. Or they can be natural structures, such as collections of driftwood washed down from rivers and onto the beach, which can block seas from carving away at bluffs.

The problem lies in the side effect, Pilkey explained. These structures, artificial or man-made, cause the ocean to eat away at the beach itself, rather than replacing it with sediment from inland. Over decades, nothing is left but the seawall and the water - no beach.

`You shouldn't be able to fish from your condominium window,' Pilkey said, showing a slide of a group of East Coast anglers doing just that.

By itself, coastal erosion isn't a problem, Pilkey said - unless there happen to be buildings threatened by it. There are three ways to respond:

The seawall method is known as "hard stabilization," and while it's the most dependable method for saving property, it degrades the beach, is costly and unsightly.

There are soft solutions - also known as beach nourishment - that involve pumping new sand and gravel to replace eroding beaches to protect the homes along them from falling into the sea. And there's bowing to the will of the sea by moving a building away from it.

"You're getting more and more riprap on your shoreline," Pilkey said. "Good luck."

After he spoke, an Oregon expert on the subject followed with a look at how the issue plays out locally. Jonathan Allan is a coastal geomorphologist with the state Department of Geology and Mineral Industries.

Oregon's coastline, he explained, has a broad range of different types of shoreline, from the dramatic rocky coastline of the south to the littoral cells of the North Coast. Seventy-two percent of the state's beaches are sandy.

Along much of the state, erosion hasn't become a problem, Allan said. But he identified a few "hot spots" where riprap structures are beginning to erode beaches, especially in Neskowin, where 14 percent of the coastline is covered in riprap.

Still, only 5 percent of the coast has riprap structures on it now, and geologists are discovering some effective ways to protect beach and inland structures by using smaller stone structures.