The Changing Shape of the Cape & Islands: The Atlantic Shoreline
As residents of the area are likely aware, these incidents in 2013 and 2015 are not isolated. In 1978, and again in 1991 and 1992, overwashes were recorded at Ballston with seawater mixing with the fresh water marsh system and the beach parking lot being flooded.
Karst Hoogeboom notes the breach at Ballston “is happening more frequently now,” most recently in the early January 2018 storm.
As previously stated, some of the sediment from the beaches from Chatham to Truro is carried north and deposited along the shores of Provincetown. In particular, Race Point Beach, near the lighthouse, has one of the highest accretion rates on Cape Cod. According to the USGS, in 2013 the rate of accretion was approximately 2.3 meters per year.
Mark Adams explains the difficulty in tracking and predicting where the biggest changes will happen. “While we understand the long-term processes,” Adams says, “in the short term we see temporary ‘hot spots’ with sudden rapid erosion, likely driven by breaks in submerged sand bars near the shore.”
One such hot spot was at Cahoon Hollow Beach in Wellfleet. On August 18, 2017, heavy rains pelted the area and collapsed a section of the parking lot of the Beachcomber restaurant, leaving a 25- by 40-foot crater in its wake. A week later a new safe pathway was opened to allow beach access again. Though it may have looked like erosion, Greg Berman says it was something different.
“I was called to the site after the sinkhole opened,” he says. “It was not ocean-driven erosion, though. It was a heavy rain event where the water pooled in the parking lot causing the ground to give way. It was nothing that could have been predicted based on incoming storms and waves like common shoreline erosion.”
Adams says that in terms of solutions to the erosion issues, it is better to adapt than it is to try to stop it. “Soft coastal protection, which includes fences and planting, can help with minor erosion,” he explains, “but it only controls foot traffic and wind. Hard protections can have a temporary effect but have consequences downdrift by blocking the flow of sand.” This means that while structures such as breakwaters protect what is in the immediate vicinity, the areas located slightly farther away become sediment starved, essentially transferring the erosion to those areas.
Tommy Dill’s conclusion is simple yet profound. “You’re not going to stop the ocean,” he says. “It’s going to do what it wants to do. Every year things change.”
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