By Kim Robson
A day at the beach is perfectly synonymous with summer. There’s nothing like strolling along the firm wet surf line with water lapping your ankles, or digging your toes into soft warm sand. And the beach invites sand castle making, burying loved ones up to their necks, setting up shade shelters, and flying kites and colorful flags. Some beaches, like California’s Santa Monica Beach or Coronado Beach, are famous for their 100-yard-plus-wide beaches.
But what can human beings do when the sand disappears? Beach sand is naturally carried down the coast and out to sea by wind, wave action and storms, eventually reducing the amount of sand until only rocks remain. It’s a big problem in tiny communities like Malibu, California, where 65 feet of beach has disappeared; and Nantucket Island, whose 150 feet of dunes have given way to crumbling bluffs reaching right up to foundation lines. Residents, local governments and the coastal commissions are waging battles over how to deal with the problem. Million dollar homes as well as legally protected public beach access are at stake.
There are a number of ways to stop the incessant beating of the sea, some more environmentally sustainable than others. Homeowners on high bluffs can spend huge amounts of their own money to have deep foundation pilings pounded into the earth, upwards of 100 feet or more, until they hit bedrock. This will protect a home from falling into the ocean, but for only a few decades, until the bluff erodes enough to expose the pilings. Some homeowners have gone to the extreme measure of physically relocating their home a few hundred feet back, away from the encroaching sea.
At Malibu’s Broad Beach, which is not at all broad anymore, residents paid to have a mile-long, 13-foot-high rock seawall installed between their homes and the crashing waves. On Nantucket Island, a handful of residents have gotten permission to try out revetments (rock or stone barriers) along a 400-foot section of the hardest hit bluffs.
The problem with stone revetments or man-made Tetrapods is simple: hard structures + wave action = no beach. The barriers do dissipate the energy of the waves very well, but they also disrupt ocean currents, marine habitats and natural erosive cycles. It’s kind of like paving over a field with asphalt. Revetments are also ugly and impossible to walk on, as all the beach sand will be gone.
Revetments also prevent or discourage public beach access, as homeowners’ property lines reach right down to the edge of the barrier. With no sand beyond the barrier, there’s no place to spread a blanket, take a walk, or enjoy the coastline unless you can be content with perching on the corner of a jagged rock as waves crash into your face.
Perhaps the most difficult problem with revetments is that the community becomes dependent on them to protect homes and businesses. There never yet has been a successful program to replace beach sand in front of revetments. The only way to do it is to have the barrier removed and replaced with sand, to which many residents are opposed. They become used to the protection the barrier provides but still want beach sand. You can’t have both.
The best and most natural protective barrier a coastline can have is a wide, well established beach. Many communities have to budget for sand replenishment or “nourishment” every ten years or so. The sand is mixed with water, then pumped up from the ocean floor and from breakwaters down the coast where it becomes trapped and collects. Eventually the sand erodes and, therefore, must be replenished every five to ten years, depending on the number of winter storms. Encouraging dunes to form and grass to grow on them helps stabilize the sand. Every winter on Coronado Beach, bulldozers pile up 25-foot-high sand dunes parallel to the sea, with gaps between them for people to get through. They’re fun to climb up and slide down, but their real purpose is to protect the beach from damaging storm surges and winter high tides. By late spring, they naturally soften to a manageable height.
There is no stopping the natural forces of erosion. Fighting erosion is a slow, losing battle, one that is fruitless and immoral to wage. Many environmentally conscious coastal residents would rather let nature take its course. With this “managed retreat,” erosion is accepted as inevitable and natural, and homes that are threatened are being demolished or moved a few hundred yards inland. In 2007, the Sankaty Head Lighthouse on Nantucket was moved 390 feet inland to save it from the encroaching bluff. The whole of Nantucket is, in fact, just a spit of land deposited by a retreating glacier after the last ice age. The ocean is slowly taking back her own.
The interests of homeowners, local residents, communities, governments, and coastal commissions are often directly at odds with the inevitable forces of nature. Erosion cannot be stopped, just temporarily slowed, often to our own detriment. If we want to enjoy our beaches, we must find environmentally sustainable ways to manage all these forces. Want to help? Save-Our-Beaches.org is dedicated to preserving and protecting our beaches and public access to them.