Coastal Development
Although nothing can be done to prevent storms, coastal engineers have made numerous attempts to control erosion through a wide range of methods. These can be classified as (1) energy dissipation through the use of hard structures or (2) supply supplemental sand to eroding beaches through dredging and beach nourishment projects. Both methods are expensive and controversial.
Through dredging of inlets and waterways, engineers are able to remove
sediment where it is accreting, and deposit sediment where it is eroding.
Beach armoring on the other hand works to maintain the integrity of the
beach prior to erosion by dissipating energy heading towards the coast from
storm-generated waves through the use of groins, breakwaters and sea walls.
Because of the dynamic nature of the coastline, most methods prove to be
only temporarily effective. As the coastline becomes more populated and
developed, the need for coastal mitigation will be in higher demand. Also,
increasing property values along the coastline will certainly yield an
increase in the costs of coastal mitigation, not just along the East Coast,
but for taxpayers nationwide.
These increased costs raise the question of economic risks involved in
coastal development, whether or not the economic benefits of coastal
development exceed these risks, and who should pay for the costly endeavor
of continuing coastal development. Our coastal areas are huge economic
drivers for seaboard states. Beach tourism brings in many millions of
dollars annually, as do commercial and recreational fishermen and other
maritime industries. NOAA claims that coastal regions are the number one
destination for tourists in America. Just as beautiful beaches foster
healthy coastal economies, eroding or unusable beaches discourage tourists
from visiting and spending.
Real-estate investment is also significant in coastal regions. United
Nations consultant Don Hinrichsen estimates in a NOAA paper that 55-60% of
Americans live in coastal regions (Atlantic, Pacific, Gulf Coast, and Great
Lakes), and notes that these areas are becoming increasingly populated.
According to Hinrichsen, 75% of Americans are projected to live in coastal
counties by 2025. It is also estimated that the combined property value for
the Outer Banks of North Carolina is near $27 billion. Clearly, such high
coastal use and property values offer an enormous economic investment,
though these regions are also in high-risk environments, prone to constant
erosion and devastating storms.
One of the most controversial issues in coastal management is who ends up
paying for the projects and who ends up benefiting. The costs of some
projects can reach hundreds of millions of dollars and many feel that the
wealthy, vacation-home owners unjustly benefit from the taxes of the general
public. The Federal Government is the largest subsidizer for coastal
projects. They pay roughly two-thirds to three-quarters of the cost, and
local and state governments cover the rest. Beach nourishment is a continual
cost that is often not factored in original estimates and can range from
$350,000 to $3 million a mile. The US Army Corps of Engineers estimates
that by 2010 the cost will exceed $58 million for coastal management
projects each year in North Carolina. The debate will continue and new
methods will develop to finance the never ending quest to maintain and
preserve our nation's coasts.
For a complete and detailed risk assessment for coastal development
including economic, environmental, societal, and hazard impacts please visit
NOAA’s Risk and Vulnerability website at:
http://www.csc.noaa.gov/rvat/data.html
____Beach Projects____
Groins
Groins are hard structures (wood, steel, or concrete) that are normally constructed in groups perpendicular to the beach, and reach out, fingerlike, into the surf zone. The goal of groins is to impede the longshore transport of sand, thus expanding the beach in the updrift side of the groin. However, groins commonly lead to severe erosion on the downdrift sides, thus a critical trade-off must be kept in mind when developing groins.
This groyne marks the southernmost reach of Hengistbury Head and is the separating point between Poole Bay in the foreground and Christchurch Bay in the distance. This was taken from the top of Warren Hill.
Breakwaters
Breakwaters are constructed in the pathways of waves with the goal of reducing the wave's energy before it hits the beach. The idea is that reducing the level of wave energy reaching the beach will also reduce the main forces responsible for beach erosion. Along with groins, breakwaters create a trade-off between sand gained behind the breakwater and sand lost at another close by site.
Harwich Breakwater
Breakwater at the entrance to Harwich Harbour, looking toward
Harwich Town
Sea walls
The concrete sea wall was built in this shape to deflect the power of the waves and to protect the dunes beyond. The large rocks seen beside it have been brought here from Norway. They were deposited alongside the seawall for protection from wave action but it did not take long for most of them to be almost totally buried in the sand and hence having lost most of their effectiveness. For comparison see this photo, which was taken
View along the sea wall
The concrete sea wall was built in this shape to deflect the power of the waves and to protect the dunes beyond. The large rocks seen beside it have been brought here from Norway. They were deposited alongside the seawall for protection from wave action but it did not take long for most of them to be almost totally buried in the sand and hence having lost most of their effectiveness. For comparison see this photo, which was taken
Dredging & Beach Nourishment
Methods of dredging have evolved over the years, and have played a crucial role in coastal development along the ever-evolving coastlines around the globe.
The beach end of the £5million Poole Harbour deep water channel dredging and beach rebuilding project, a 24 hour/7day contract throughout December 2005 and January
____Coastal Management Issues____
Coastal management encompasses an array of agencies and agendas. Though all contribute in their own way to coastal management efforts, it is the Office of Ocean and Coastal Resources Management (OCRM) section of the National Oceanic and Atmospheric Administration (NOAA) that is primarily responsible for implementing the federal Coastal Zone Management Act (CZMA), which was established with the intent of cohesively setting goals for the national management of beaches. Because management programs are distributed among many different agencies it is important to consider coastal zone management from both national and local perspectives.
State and local agencies are key players as they have an increased ability
to create site specific regulations. The CZMA provides states with
management power and, in turn, many states require local governments to
draft and enact planning requirements that must meet certain standards.
However, ecosystems and beaches don’t correlate with state or county lines
and as a result regional and multistate administration programs also exist.
Some of these agencies enforce the management and
installation of jetties, dikes, groins, breakwaters, and seawalls. Others
attempt to use creative thinking, engineering, and education to construct
more sustainable, ecologically friendly designs and planning initiatives.
With so many involved agencies at various levels, the
intricacies of the coastal management network are complex, but through them
arises the opportunity for innovative new ways to interact with and manage
the coast.