Environment and development in coastal regions and in small islands |
alternative PDF version
Wise practices for coping with beach erosion: Anguilla
Department
of Fisheries and Marine Resources, Anguilla
University of Puerto
Rico, Sea Grant College Program
Caribbean Development Bank
UNESCO
Environment and Development in Coastal Regions and in Small Islands
FORCES
TO BE RECKONED WITH
Beaches
are continuously changing – from day to day, month to month and year to year
– as the natural forces of wind and water meet the land. These changes, which
have been taking place for millions of years, are linked to variations in wind,
waves, currents and sea level height.
But
it is not just natural forces that change the beach, humans have a big role to
play in this process as well, through mining stones and sand from the beaches
and dunes, polluting and damaging coral reefs, and constructing buildings and
walls too close to the sea.
Changes
in the beaches affect everyone. The coast is a place we are all attracted to for
recreation, sports and simple enjoyment. This constantly changing and
hazard-prone coastal environment is also where the greatest financial investment
is concentrated, as large tourism properties and establishments continue to be
attracted towards Anguilla’s shores. Tourism is a driving force in
Anguilla’s economy so the state of its beaches is of major importance.
Natural
forces
Since
1995, the Atlantic Basin (including the Atlantic Ocean, the Caribbean Sea, and
the Gulf of Mexico) has entered a more active hurricane cycle, which may
continue for more than 20 years. |
Hurricane frequency between 1990 and 1999 in the Atlantic Basin |
Source: Gray et al. http://typhoon.atmos.colostate.edu/forecasts/1999/nov99/ |
In
the Atlantic Basin the number of really severe hurricanes (categories 3, 4 and
5) increased from one per year (1990 –1994) to four per year (1995 – 1999).
Human
forces
|
It
was unwise to rebuild a beach bar at Sandy Island in October 1995 immediately after Hurricane Luis, as waves reshaped the cay leaving the structure in the sea |
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WHAT’S
HAPPENING WITH ANGUILLA’S
BEACHES?
Shoal Bay in 1992 |
In
order to manage these changes, Anguilla’s beaches have been monitored since
1992 by the Department of Fisheries and Marine Resources, who measure the beach
slope and width every 3 months at numerous sites around the island, as well as
at the offshore cays. |
Beach
monitoring |
Location
of monitored beaches
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SAND
IN,
SAND OUT
When
Hurricane Luis struck in 1995, much of the beach was lost at Mead’s Bay on the
north coast. In the months and years after the hurricane the beach recovered,
but not to the pre-hurricane level.
BEACH
PROFILE |
Beachfront
properties were transformed overnight after Hurricane Luis struck in 1995. Mead’s Bay Central: reference point before and after Hurricane Luis |
|
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DUNES AS RESERVOIRS OF SAND
Dunes
function as reservoirs of sand, supplying beaches during storms and protecting
coastal land from flooding.
BEACH
PROFILE |
At Cove Bay there used to be an extensive line of sand dunes separating the salt pond from the sea and measuring more than 3 metres high. In 1995 Hurricane Luis eroded the seaward face of these dunes and in 1999 the waves generated by Hurricane Lenny broke through the dunes in places, joining the salt pond to the sea. | |
|
Sandy Ground. During Hurricane Lenny (Nov. 1999) the sea and the pond were temporarily joined |
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WISE
PRACTICES FOR A HEALTHY BEACH
Seagrape trees
|
The
state of the beach affects everyone’s lives. There are no simple or universal
solutions to shoreline erosion, since there are often several factors, both
human and natural, contributing to the problem at a particular beach. Each beach
behaves differently, so it is advisable to find out as much information as
possible about a particular beach before taking any corrective action. It is
necessary to consult the Department of Physical Planning before undertaking any
action at a beach. Some
forces of change, such as hurricanes and winter swells are natural, and there is
little we can do to stop them, yet there are ways we can help to slow down the
rate of erosion:
|
Recommended
coastal development setback distances in Anguilla |
|||
l l |
(18m
(60ft) FROM VEGETATION LINE |
l l |
45m
(150ft) FROM VEGETATION LINE 92m (300ft) FROM VEGETATION LINE |
Sand
fences and sea lavender, Shoal Bay, 1998 |
Planting dunes with native grasses, Maunday’s Bay, 1996
|
|
|
Planners
and a developer discuss a recently constructed seawall at Mead’s Bay, Anguilla, 1998 |
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HERE
TODAY,
GONE TOMORROW
The table shows generalised rates of change at the measured beaches in Anguilla. During the 1990s, all of the beaches, with one exception, showed erosion, a result, at least in part, of the impact of several severe hurricanes since 1995. However, most beaches in Anguilla show erosion along one part of the beach and accretion (or build-up) at adjacent sections, thus these figures must be treated as average trends.
Beach change rates in Anguilla (metres per year) |
A
negative rate of change (–) indicates erosion and retreat of the shoreline, a
positive rate of |
Maunday’s
Bay after Hurricane Lenny in 1999. |
Measuring sand loss after Hurricane Luis, 1995 |
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|
For
more information on shoreline Department
of Physical Planning Department
of Fisheries and Marine |
For
more information on shoreline Coping
with Beach Erosion This
booklet is a result of co-operation |
Illustrations: Barbara Navi – Photographs: Gillian Cambers – Design: Eric Loddé
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