Traditional methods of stabilization - seawalls, groins and breakwaters - are increasingly
being identified as leading to the erosion of fronting and downdrift beaches. For
the last thirty years, coastal homeowners and town managers have sought low-cost,
effective alternatives. In response, a number of "non-traditional" devices with optimistic
sounding names have appeared on the market.
The following is a listing and brief description of many alternative devices. Also
included is a qualitative analysis outlining the potential negative impacts of each
device. It is important to note that few of these devices have been sufficiently field
tested (five years or more to accurately assess the ability to withstand severe storms)
while some have never been field tested at all.
Potential Negative Impacts
As an extension of the problems previously listed, devices were assessed as to associated
negative impacts. This analysis is based on media reports, first-hand accounts and
our own personal experience with shoreline devices and coastal processes. The following
negative impacts were evaluated for each device:
- Reduces Beach Access: This applies to any device placed on the beach that restricts
lateral or cross-shore access, access to the water, or restricts swimming areas.
- Erosion of downdrift beaches : Devices that restrict transport of sand, either cross-shore
or alongshore will lead to erosion elsewhere.
- Erosion of fronting beaches : Applies to devices that cause wave reflection, that
prevent landward migration of beaches, or which cut off the local sediment supply.
- Potential hazard to swimmers : A device placed in the shallow nearshore zone poses
a threat to swimmers. Devices that alter currents or flow present a possible threat,
especially when used in conjunction with a groin. Water that flows onshore must flow
offshore. When offshore flow is impeded, water will flow along shore until it can
be released, creating a separate longshore current. When a breakwater is placed near
a groin there is usually a space between the two. This is the preferred path for water
flow, and leads to the Venturi effect. Water that flows through a narrow, straight
opening, will create an undercurrent suction, similar to that of a rip current. This
could result in swimmers being pulled offshore.
- Impact to water quality: A key factor in preserving water quality is dilution of pollution
through circulation. A reduction in the flow of water, reduces the circulation and
can effect water quality. This category applies to those devices that impede water
flow, or that trap floating debris.
- Impacts turtle nesting: Not only are devices that impede the path of turtles across
the shore a concern, but more important, are those that may alter the temperature
of the sand. The sex of turtles is determined by the temperature at which they are
incubated. Devices that effect the temperature of the soil may cause overselection
for one sex.
- Impacts on clam resource: Of great concern, especially on the west coast, is the clamming
industry. Any device placed on the nearshore, or at the low tide line may impact the
access to the clams and the resource itself by compacting the sand.
- Impairs aesthetics: One of the primary reasons for development along the coast is
because people are drawn to its natural beauty. Devices that are placed on the beach
or above water detract from the scenery and overall aesthetics.
Alternative stabilization devices survey:
Western Carolina University PSDS (including its employees and agents) assumes no responsibility
for consequences resulting from the use of the information herein, (or from the use
of the information obtained at linked Internet addresses,) or in any respect for the
content of such information, including (but not limited to) errors or omissions, the
accuracy or reasonableness of factual or scientific assumptions, studies or conclusions,
the defamatory nature of statements, ownership of copyright or other intellectual
property rights, and the violation of property, privacy, or personal rights of others.
Western Carolina University PSDS is not affiliated with, nor do we endorse, any of
the devices listed; is not responsible for, and expressly disclaims all liability
for, damages of any kind arising out of use, reference to, or reliance on such information.
No guarantees or warranties, including (but not limited to) any express or implied
warranties or merchantability or fitness for a particular use or purpose, are made
by Western Carolina University PSDS with respect to such information.