By Chuck Ross
Owning an oceanfront retreat can be a lifelong dream for some homeowners. Buyers will pay a high premium for the opportunity to fall asleep to the sound of surf and wake to the sight of brilliant waterfront sunrises. But such locales pose dangers beyond the obvious hurricane risks. The slow but steady work of coastal erosion can be just as damaging to such properties as hurricane-force winds, and builders who ignore potential pitfalls risk turning their clients' dreams into very expensive nightmares.
A problem that's not eroding
Regardless of their positions on global warming, scientists agree that erosion is a growing issue along coastal areas. A combination of rising sea levels and subsiding land masses — especially along the Northeast coast — means more land is going underwater.
"Everyone in coastal communities is facing this problem," says John Bologna, president of Coastal Engineering Co., Inc., based in the Cape Cod town of Orleans, Mass. "You can look back 100 years or so and see that we've got a rising sea level. That's a geological process."
Not all erosion is the same
However, although the problem of erosion is universal, its impact can vary greatly, even in just a few miles' distance, based on local conditions such as offshore shoaling, prevalent wind directions, local tide heights and the presence of manmade structures. Additionally, not all erosion is permanent.
Spencer Rogers, a specialist in shoreline processes and shoreline construction for North Carolina Sea Grant, outlines four different causes of erosion:
- Seasonal fluctuations in the shape of a beach due to changes in wave patterns. This process, in which winter and spring storms force sand offshore and summer waves push that same sand back onto the beach, is typical to most East Coast beaches.
- Storm-induced changes due to extreme Northeasters or hurricanes, caused by storm surges. These events can move sand further offshore, but it often is gradually pushed back to the beach.
- Long-term chronic loss of sand due to sea-level rise and land subsidence.
- Changes due to movement around shifting inlets.
Long-term losses and inlet-related changes pose the biggest risk to structures that are otherwise built to withstand storm-related forces, Rogers says. Staying away from inlet sites is an easy way to avoid those risks, but damage due to long-term forces can be harder to address.
"It's the most difficult to deal with," Rogers says.
Get professional help
Builders investigating coastal locations as potential building sites should seek out additional professional help. Coastal engineers — oftentimes a civil engineer with a background dealing with local coastal conditions — can be a critical team member on such projects. In addition to erosion control, coastal sites can pose a number of regulatory challenges due to environmental concerns, and added guidance from a pro who understands the rules and approval processes can be key to success.
"In the old days, you just picked the best view and put the house there," Bologna says. "Now the market is demanding more foresight."
The hard and soft of it
An engineer also can outline options for protecting coastal properties, based on the local geography and regulations. Bologna separates these approaches into "hard" solutions, such as wall-like bulkheads and revetments, and "soft" solutions, such as fiber rolls, snow fencing and beach-nourishment efforts.
Hard solutions, which also can include offshore jetties and groins placed at right angles to the shoreline, can face stricter scrutiny from coastal officials. In many areas they simply are not allowed. Soft solutions, which can require regular observation and maintenance, may be the only option in such jurisdictions.
Bologna says fiber rolls are a soft-solution approach that is gaining approval along the Massachusetts coast, where hard solutions are only permitted when buildings on the site pre-date 1978. The rolls are constructed of sturdy coconut fibers and wrapped in a nylon mesh. They are stacked and anchored onto an embankment and topped by a fresh layer of sand. New plantings are then added to provide further stabilization.
Everything must change
One of the biggest challenges in designing protective solutions, whether hard or soft, is that shorelines rarely stay in one place, even in the best conditions, and even the least intrusive solution is likely to affect adjacent properties. As a result, today's property-by-property approach, managed by a patchwork of local, state and federal agencies, can make matters worse for some homeowners, even while they help others.
"Everything is so interconnected," Rogers says. "For every grain of sand you trap on one side, that's a grain that won't go to the other side."
Chuck Ross is a freelance writer who specializes in construction-related topics. As a resident of Cape Cod, he is also very familiar with the issues related to coastal building.
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