Some blame replenishment for crushing waves

Surfers get better waves along Delaware's coast where the slope from the shore to deeper water has not been altered by "replenishment" – pumping sand from offshore onto eroded beaches.

Natural beaches also are safer for swimmers because waves break further into the ocean, spreading energy across a wider area rather than slamming it all onto shallow water.

But all of Delaware's municipal ocean beaches have been replenished since the 1990s, and those slopes are steeper, giving waves more power when they hit the beach.

John Doerfler, chair of the Delaware Chapter of the Surfrider Foundation, said there are few places left in Delaware where surfers can ride the crest of a wave as it breaks on a near-shore sandbar 30 yards or more from the beach.

"You can't surf in Delaware anymore," he said, at least not at the replenished beaches.

Those beaches are typically created with big earth-moving machines on a steep, 10 to 1 grade. A natural beach is typically a 20 to 1 grade, meaning the drop off is much more gradual, and waves break further off shore.

State environmental officials are beginning to question whether the approach to replenishment should be modified.

"Have we steepened our beaches?" asked Anthony P. Pratt, the state shoreline and waterway manager. "We're asking that scientific question."

The goal is to ensure that beaches are as safe as they can be, Pratt said.

State officials have long assumed that sand would shift months after a replenishment project and take on a natural profile.

The principal was that "nature prevails on the slope," he said.

But now state officials are working with David Kriebel, chair of the U.S. Naval Academy's Naval Architecture and Ocean Engineering Department, to review decades of shoreline data to determine if replenishment projects have altered the shape of Delaware's beaches. Pratt said they will examine years of state data and field assessments done by the Army Corps of Engineers.

"Certainly, safety comes to the fore," he said.

Pratt said the study will likely help both the state and the Army Corps Philadelphia District fine tune ocean beach re-nourishment projects.

Delaware has been doing major ocean beach replenishments since 1994, when the state spent $2.4 million to pump thousands of cubic yards of sand on the badly eroded and storm-damaged Dewey Beach. They spent $1.1 million to do the same thing in Rehoboth Beach in 1998. In those cases, the sand came from just off shore. Rehoboth's sand was initially pumped from Hen & Chicken Shoals, just northeast of Rehoboth at the entrance to Delaware Bay.

Since then, millions in federal dollars have been spent to build storm-ready, engineered beaches and dune systems on public, municipal beaches from Rehoboth south to Fenwick Island.

Pratt said with that first replenishment project, the sand was such high quality that it yielded a beach with a gradual slope and waves that broke further offshore.

In 2006, a sand source that included small pebbles was pumped on shore, and the state was flooded with complaints from beachgoers who were pelted with rocks in the surf.

With or without replenishment, Pratt said, waves have always broken close to the shore on Rehoboth Beach.

Kimberly McKenna, a coastal geologist with the state's shorelines and waterways management section, said that's because Rehoboth sits 20 feet above sea level. And Rehoboth doesn't have near-shore sandbars, which slow the crushing power of the waves before they hit the beach.

Doerfler said he hopes the state and the Corps begin to design gentler slopes on replenished beaches, as New York, New Jersey and North Carolina are already doing.

The downside is that it costs more to build a beach with a more natural slope. And nearly every year, there is a battle in Congress over whether money will be provided for future beach nourishment projects.

Reach Molly Murray at 463-3334 or mmurray@delawareonline.com. Follow her on Twitter @MollyMurraytnj.