If seawalls are too expensive and cause almost as much erosion as they prevent are there other ways to protect a coast? Another barrier beach island on Florida’s Gulf Coast provides an answer. Gasparilla Island is half a mile wide and seven miles long. Celebrities as disparate as Harrison Ford and the entire Bush clan stay at the Gasparilla Inn and Jimmie Buffet often visits his sister at the south end of the island.
A string of tasteful old Gasparilla homes line the Gulf of Mexico shore. Most of the houses languish behind a ten foot seawall. For decades if you wanted to swim in the Gulf you had to clamber down the seawall and swim between rusty old groins. Most owners preferred to swim in their own private pools. Fishermen cleaned their catch on the seawall and threw scraps to the sharks that regularly patrolled the runnels between the offshore bars. Each wave would dislodge teeming colonies of mole crabs and coquina shells that dug furiously to rebury themselves before the next wash carried them offshore. Every spring, sea turtles laid their eggs in the powdery white sand .
All that changed in 2006. After seven years of lobbying, Lee County officials finally persuaded Congress to fund a $13 million dollar beach renourishment project. Renourishment has become engineers’ favored “soft solution” to deal with coastal erosion. During the 1970s and 1980s coastal geologists demonstarted that “hard solutions” like seawalls create more erosion than they prevented because they scoured away the beach in front of seawalls. But there are problems with “soft solution” as well.
I was able to visit Gasparilla Island halfway through a beach renourishment project in 2007. The experience allowed me to tally up some of the pluses and minuses of the procedure. The biggest plus was the beach itself. You no longer needed to clamber down the ten foot seawall. You merely stepped over the top of the seawall and onto the brand new beach. But a significant short term minus was the rusty, four- foot diameter pipeline that emerged from the Gulf then snaked its way two miles down the beach. All night you could see the lights of the offshore barge sucking up tons of sand, shells and water from Boca Grande Pass and pumping them through the submerged pipe to the shore. All day long you could hear the quiet scrapping and scratching of the shells as they sluiced through the exposed pipe in a slurry of murky gray water.
A mile down the beach, workers diverted the pipeline into two pipes lying parallel on the beach. A valve switched the slurry into the offshore pipe and a 30-foot grey geyser of water, sand and shells shot down the beach. After the new sand formed a peninsula running parallel to the shore, the engineers switched the flow to the inland pipe that blasted more sand to fill in the area behind the peninsula. After the entire segment of beach was buried eight feet deep in sand, bulldozers flattened the beach and new pipes were added to the ever growing pipeline. In this manner, the project moved down the coast adding 300 feet of new beach every week.
A year ago sharks and dolphins swam in what was now a three mile long, eight foot deep berm of gray shelly sand. It would take five years for the mole crabs, coquina and other invertebrates to restablish themselves. But it didn’t look like the beach would last even that long. The night after we arrived a cold front swept in off the Gulf of Mexico and six foot waves battered the new beach. In a matter of hours the storm removed 20 feet off the face of the beach. The equivalent of several football fields filled eight feet deep with sand had been washed away.
Cold front storms occur frequently along this coast. In less than six months most of this sand will have washed away, only twenty feet of beach will remain. This looked like a modern version of King Canute’s attempt to thwart the tides. But looks can be deceiving. After the storm passed my wife and I were able to snorkle offshore. Gentle waves had created a foot high ledge of shells along the edge of the beach. We were able to swim along this underwater ledge collecting the best shells as they tumbled down the face of the miniature cliff. But once we swam beyond the small ledge we were swimming over a shallow plateau of new soft sand. The waves had already winnowed most of the shells out of the sand. The theory behind this project is that most of the sand will stay in a three mile long offshore cell of sand, and when major storms attack the underwater sand will absorb the waves energy to prevent damage to seaside homes and condominiums.
However, there are always problems when theory runs into reality. The project had originally called for the construction of an offshore breakwater and two T-groins to contain the sand within a three mile long sand cell. Unfortunately, bids for the structures had come in double what they had been budgeted for, so the project proceeded without them. This allowed storms to push sand back into the depths of Boca Grande Pass losing it to the offshore sand cell. Plus, an auxillary pump broke down two months into the project, threatening to extend its completion until well into the turtle nesting season.
But the most ludicrous situation arose as homeowners realized that the public might actually want to use the beach their taxes had paid for. This meant they would also want to park on the shell lined roads that led to the beach. But the homeowners had come to think of both the roads and the beach as their own private property. When I arrived residents were frantically planting twenty foot high palm trees on both sides of the roads to prevent parking. Evidently the homeowners would rather lose their homes than have the public exercise its right to use the roads and beach.
With all the glitches, it is doubtful that the Gasparilla project will remain effective for its projected seven years. Even if does, Congress will have to continue spending $13 million dollars every seven years to renourish this coast. At that rate, it will cost about $4 million dollars every seven years to protect a mile of this coast. Should the public pay so much money to defend private beachfront homes? That is the ultimate problem with beach renourishment, it costs a lot of money for what is ultimately a short term, bandaide solution to coastal erosion.
The other problem is sea level rise. While we were snorkeling my wife discovered a large lightning whelk. The side of the whelk’s shell contained a curious three quarter inch hole. It was only after we returned home that we realized that the hole had been chipped into the side of the shell to hold the end of a wooden handle. My wife had discovered an ancient Callusa axe. Several hundred years ago, when Gasparilla Island had been a tenth of a mile further out to sea, the area we had been swimming over had been a Callussa village. This island like all barrier beach islands has been retreating since the end of the last Ice Age. A $13 million dollar beach renourishment program is not going to stop the effects of sea level rise.