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Geophenomena
Seawalls
and Sandbags
By Orrin H. Pilkey
and Matthew L. Stutz
The owners of the Villa Capriani Condominiums on North Carolina’s North
Topsail Island recently built a permanent seawall of stiff vinyl plastic
and heavy posts to protect a swimming pool from beach erosion. The seawall
violated state law, and the state brought the condo owners to court. But
the judge of the North Carolina state court ruled in the owners’ favor.
He said, in effect, that it’s true the seawall violates the law, but
the wall is doing no harm right now so let it stay. The judge could not
see the long-term, geologic consequences of the owners’ actions.
This ruling is just the most recent of many blows to North Carolina’s
regulation of seawalls and, as a result, its ability to protect its beaches.
Seawalls built on eroding shorelines destroy beaches. Although they can
hold the shoreline in place, seawalls cannot hold the beach in place. After
a seawall is erected, the beach backs up against the wall, eventually narrowing
to nothing. |
A sandbag seawall in
South Nags Head, N.C., as it appeared
in 1997. The wall is
higher and longer than it was in 1987. The
varying colors of the
sandbags, first installed as a “temporary”
barrier, indicate
the wall was rebuilt many times.
Courtesy of Orrin Pilkey. |
It looked like North Carolina had solved its seawall problem in 1985
when it passed ground-breaking regulations prohibiting seawall construction.
At the time, only 5 percent of North Carolina’s developed shoreline was
armored with seawalls, compared with 55 percent in west peninsular Florida
and 50 percent in New Jersey.
The legislation included one exception: If a building will soon topple
into the sea, a temporary sandbag seawall can be built to protect it until
the building is moved. The bags must be removed in two years. Sandbags
are no different than concrete walls when it comes to beach destruction.
Their one advantage is that they can be removed easily and cheaply.
This exception for sandbags has become the legislation’s Achilles heel.
Since 1985, sandbags have grown from 50 pounds to seven tons with new sandbag
technology imported from Florida. Also, North Carolina has proved incapable
of enforcing sandbag removal. Hundreds of sandbag seawalls, some as long
as 1,200 feet, now adorn our beaches. Some have remained in place for over
a decade.
The engineering community has fought the notion of seawall-induced beach
loss long and hard and a few engineers still do. One reason for their resistance
is that they are “customer oriented.” It is unthinkable that a homeowner
or a community shouldn’t be allowed to prevent their property from falling
victim to the sea. Politicians are also customer oriented, operating on
election-cycle time scales of six years or fewer.
But the loss of beach in front of a seawall can take three to four decades
on the East Coast and Gulf Coast. Regulatory enforcement, on the other
hand, has immediate political, economic and societal impacts that a government
is seldom willing to risk. If beach loss took one year instead of four
decades, people could easily see and respond to the problem. In our view,
the long-term nature of the geologic process of beach loss is the reason
North Carolina is failing to protect its beaches.
In contrast to its management of beaches, North Carolina has initiated
an ambitious, proactive approach to regulating river flood plains. The
state is buying structures that have been repeatedly flooded, and has spent
$60 million since Hurricane Floyd last fall. But on the beaches, the state
is about to sign off on a $1.6 billion, 14-mile-long renourishment project
for the Outer Banks that will secure the status quo for the next 50 years.
The cost of buying out all the buildings and property that will be affected
by the project would be only one-fourth that amount. As with flood plain
management, relocation and buyouts are the most prudent and economical
long-term approaches to beach management.
Few beachfront property owners view seawall-induced beach loss as a
problem. For them, their property is more important than the beach. Although
its details are different, the seawall dilemma is not unlike the problem
of allowing buildings on eroding sea cliffs, along landslide-prone hills,
in river floodplains, and at the base of a boulder-strewn slope. But people,
if they even recognize the hazard, consider the likelihood of cliff erosion,
landslides, floods and boulder falls to be a roll of the dice and they
are willing to take the chance. Beach loss in front of seawalls, on the
other hand, is a certainty on eroding shorelines.
Even when everyone agrees the outcome of a geologic process is certain,
we don’t respond well and we leave the problem for the next generation.
Clearly we have a long educational road ahead of us to convince the public,
our engineers and our politicians to take a realistic view of the long
haul.
Pilkey is a professor emeritus and Stutz
is a Ph.D. candidate, both in the Division of Earth & Ocean Sciences
at Duke University, Durham, NC 27708.
E-mail: mls4@duke.
edu
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Storm
Tropical storm Bebinca slammed the Philippines’ east coast early Nov.
2, packing winds of 69 mph as it moved on its west-northwesterly path over
the main island of Luzon. Bebinca hit the storm-ravaged archipelago following
the deadly typhoon Xangsane, which killed scores of people in the Philippines
and Taiwan earlier in the week and were a cause of the runway crash of
a Singapore Airlines jet in Taipei.
Landslide
At least 40 people in Indonesia were buried alive during the first
week of November as torrential rains in southern parts of densely populated
West and Central Java triggered numerous landslides. More than 4,000 people
have been left homeless in the destruction caused by the slides. Construction
crews struggled to reopen the region’s main roads, including the Trans
Java Highway.
|
Associate Editor Christina Reed compiles
Geophenomena.
