Environment and development in coastal regions and in small islands |
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Wise practices for coping with beach erosion:
St Lucia
Fisheries Department, St Lucia
Physical Planning Department, St Lucia
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 the 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, cutting and clearing coastal vegetation, 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 attracted to for recreation, sports and simple enjoyment. In addition, it provides a source of employment for many people. 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 St Lucia’s shores. Tourism is a driving force in St Lucia’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 |
Building on the |
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WHAT’S
HAPPENING WITH ST LUCIA'S
BEACHES?
Beach monitoring in progress at Malgretoute, 1995 |
In order to manage these changes, St Lucia’s beaches have been monitored since 1995 by the Fisheries Department, who measure the beach slope and width at regular intervals at numerous sites around the island |
Winter swells at Reduit Beach seasonally erode the beach and threaten beachfront buildings, 1995 |
Location
of monitored beaches in St Lucia
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SAND IN, SAND OUT
Beaches change from season to season and from year to year. For example along the western side of the Causeway which joins Pigeon Island to the mainland, erosion has been taking place since the Causeway was constructed in the 1970s. Monitoring results show that between 1990 and 1995 the edge of the Causeway retreated inland 10 m.
BEACH
PROFILE |
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The western
side of the
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The erosion is
also
|
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DUNES AS RESEVOIRS OF SAND
Dunes are an important part of the coastal system and function as reservoirs of sand, supplying beaches during storms and protecting coastal land from flooding. Many dunes have been damaged or destroyed over past decades in St Lucia as a result of sand mining and the construction of buildings.
These
vegetated dunes |
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Detail of |
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Clearing
dunes and
|
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Mining
sand from dune systems
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HERE
TODAY,
GONE TOMORROW
St Lucia has been impacted by several tropical storms and hurricanes during recent years. These events cause considerable damage to coastal areas, as well as eroding beaches and dunes. In the months and years after the hurricane event, the beaches recover to some extent, but not usually to pre-hurricane levels.
In 1995, St Lucia’s beaches were impacted by Tropical Storm Iris and Hurricane Luis. At Vigie Beach there was erosion and the beach narrowed by 11 m.
BEACH
PROFILE |
Vigie Beach
after |
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Debris
covering the |
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WISE
PRACTICES FOR A HEALTHY BEACH
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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 Physical Planning Department 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:
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Ensuring new
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Buildings close to the beach
are vulnerable to erosion |
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Buildings at a ‘safe’
distance from the beach are less |
Extracting
pumice for
|
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Only a
narrow beach exists in front of this retaining wall at |
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Groynes, as seen here at Wyndham Bay in 2001, result in sand build-up on one side of the groyne... |
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…and
erosion on |
Recommended coastal development setback distances along the north-west coast of St Lucia |
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l l |
15m
(50ft) 24m (80ft) |
l l |
36m (120ft) 49m (160ft) |
MEASURED FROM VEGETATION LINE |
Key to the beach numbers | |||||||
1 2 3 4 5 |
Le Sport Anse Becune Causeway Gros Islet Reduit Beach |
6 7 8 9 10 |
Trou Gaston Trou Ya Cuti Cove Labrellote Bay Marisule Beach |
11 12 13 14 15 |
Choc Beach Vigie Beach Tapion La Toc Bay Anse Fere |
16 17 18 19 20 |
Marigo Roseau Bay Anse Pilori Trou l’Oranger Anse La Raye |
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For
more information on shoreline Fisheries Department, Fisheries
Complex Physical Planning Department |
For
more information on shoreline Coping
with Beach Erosion
This
booklet is a result of |
|
Illustrations: Barbara Navi – Photographs: Gillian Cambers – Design: Eric Loddé