Wise practices for coping with beach erosion Grenada

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Environment and development
in coastal regions and in small islands

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Wise practices for coping with beach erosion: Grenada

National Science and Technology Council, Grenada
Ministry of Agriculture, Forestry, Lands and Fisheries, Grenada
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 the shores of Grenada, Carriacou and Petit Martinique. Tourism is a driving force in the country’s economy so the state of its beaches is of major importance.

Natural forces

Hurricanes and tropical storms, occurring between June and November, cause dramatic beach changes usually resulting in serious beach erosion.
High waves in winter resulting from storms in the North Atlantic Ocean, and known as swell waves, or locally as ‘groundseas’.
Sea-level rise, which is a long-term factor, taking place very slowly over decades causes shorelines to retreat inland.

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

Removing sand from beaches and dunes for construction purposes causes erosion and the loss of beaches and coastal lands, destroying the natural heritage of the coast and reducing the vibrancy of the tourism industry.
Building too close to the beach interferes with the natural sand movement and may impede beach recovery after a serious storm or hurricane.
Badly planned sea defences may cause the loss of the beach, and of neighbouring beaches.
Pollution from human activities on the land may damage coral reefs and seagrass beds; these biological systems protect, and provide sand to the beaches.
Removing vegetation from the dunes destabilises these protective sand barriers; and clearing sites inland results in increased soil and dirt particles being washed offshore and smothering coral reef systems.

Plastic and other
debris on the
beach at Petit
Martinique
eventually
washes into the
sea and impacts
marine life, 2000

***********

WHAT’S HAPPENING TO OUR BEACHES?

Beach monitoring
in progress at
Magazin Beach,
1995

In order to manage these changes, Grenada’s beaches have been monitored since 1985 by the National Science and Technology Council, together with the Fisheries Division, Lands and Surveys Division, and the Land and Water Resource Unit. The Hillsborough Secondary School and the Fisheries Division have measured Carriacou’s beaches since 1997. They measure the beach slope and width every 3 months at numerous sites around the islands.

Boat building on
beaches, a
tradition in Petit
Martinique, 2000

Location of monitored beaches in Grenada

***********

SAND IN, SAND OUT

When Hurricane Lenny struck in 1999, many of the beachs in Grenada, Carriacou and Petit Martinique were severely eroded. In the months and years after the hurricane the beach recovered, but often not to pre-hurricane levels.
Damage to the coastal road at Havey Vale, Carriacou, resulting from Hurricane Lenny in 1999

BEACH PROFILE
Harvey Vale, Carriacou. Beach erosion

Location of monitored beaches in Carriacou

***********

HURRICANES WREAK HAVOC

BEACH PROFILE
Grand Anse Central, Grenada. Beach erosion


	Grenada’s Grand Anse beach, popular among island residents and well known to visitors and tourists, was also severely eroded during Hurricane Lenny. However, sand started to come back in the weeks following the hurricane.
Aerial view of a hurricane		A famous nightclub at Grand Anse, Grenada, 1987
		Much of this same building was reduced to rubble by Hurricane Lenny in 1999

***********

HERE TODAY, GONE TOMORROW

The table shows generalised rates of change at the measured beaches in Grenada and Carriacou. In Grenada, most of the west coast beaches have shown erosion, while in Carriacou, the picture is more varied. Many of the beaches 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. The tri-island state has only been impacted by one severe hurricane during the period of measurement.

Eroded tree roots
at Grand Anse,
Grenada, after
Hurricane Lenny,
1999

Beach change rates in Grenada between 1985 and 1999 (metres per year)

Beach change rates in Carriacou between 1997 and 1999 (metres per year)

A negative rate of change (–) indicates erosion and retreat of the shoreline, a positive rate of
change (–) indicates accretion or advancement of the shoreline towards the sea

***********

WISE PRACTICES FOR A HEALTHY BEACH

Natural beach
vegetation at
Lower Paradise Beach,
Carriacou, 2000

Sea grape planted
at Grand Anse
after Hurricane
Lenny, 2001

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 Unit 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:

Planning new development so that it is a ‘safe’ distance behind the beach will reduce the need for expensive sea defence measures in the future.
Revegetating dunes with native vegetation e.g. grasses and vines, and planting beach areas beyond the reach of storm waves with salt-resistant, deep-rooting trees, such as sea-grape. (Additional development controls are required in the fragile offshore cays.)

Ensuring new development is a ‘safe’ distance from the dynamic beach zone, helps conserve the beach and the buildings		Buildings close to the beach are vulnerable to erosion
		Buildings at a ‘safe’ distance from the beach are less vulnerable to erosion


Graves being eroded, Tibou, Carriacou, 2000	Hard engineering structures, such as this rock revetment at Victoria, Grenada, serve to protect the land, in this case, the coastal highway from erosion; but they do not promote the build-up of sand, 1999 Rebuilding the beach after Hurricane Lenny, 1999 This newly constructed building at Carriacou is on the beach and is very vulnerable to hurricane waves, 2000
Resorting to ‘hard’ engineering structures such as seawalls, revetments and bulkheads, only when there is a need to protect beachfront property from wave action. Such structures, even with careful design, result in the loss or narrowing of the beach over time. Considering all other beach enhancement measures such as offshore breakwaters, groynes and beach nourishment (placing sand from the offshore zone or from an inland source on the beach) at a particular site. All such measures require careful design and environmental impact assessments, so always first consult the Physical Planning Unit.
Planting this low dune in front of a hotel may help to stabilise the dune and protect the hotel, 2001
This hotel at Grand Anse, was positioned well behind the dynamic beach area and was safe from Hurricane Lenny’s waves, November 1999

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	WISE PRACTICES CHECKLIST
	Plan for existing and future coastline change by positioning all new development (large and small) a ‘safe’ distance landward of the vegetation line (consult the Physical Planning Unit for information on ‘safe’ distances).
	Review and carefully consider ALL options when planning ways to mitigate beach erosion, these should include planning, ecological and engineering measures.
	Continue to monitor the rate of coastline change and share the findings with all stakeholders.
	Involve all stakeholders (e.g. government agencies, coastal communities, non-governmental agencies, coastal residents, beach users and others) in the improvement of beach facilities.
	Provide for improved beach cleaning through government and private initiatives, education and awareness efforts, and proper sewage disposal.
	Develop principles for coastal stewardship so that everyone plays their role to the fullest.
	Respect the rights of all beach users.
	Stop the mining of sand and stones from beaches and dunes in the tri-island state and utilise alternative sources of construction material.
	Implement policies to control the number of visitors to certain very sensitive sites e.g. Sandy Island.
	Conserve and restore vegetative cover, both adjacent to the beach in order to stabilise the sand, and further inland to reduce sediment reaching the reefs and sea grass beds.

For more information on shoreline
change in GRENADA consult:

National Science and Technology Council,
Marine Villa, Tanteen
St Georges, Grenada
T: 1 (473) 440 3118
F: 1 (473) 440 9292

For more information on shoreline
change in the CARIBBEAN consult:

Coping with Beach Erosion
by Gillian Cambers
UNESCO Publishing, 1998
ISBN 93-3-103561-4

This booklet is a result of co-operation between UNESCO, the Caribbean
Development Bank and Grenada’s Government agencies

Illustrations: Barbara Navi – Photographs: Gillian Cambers – Design: Eric Loddé

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