|Environment and development
in coastal regions and in small islands
ANALYSIS OF BEACH
CHANGES IN ANTIGUA AND BARBUDA 1996 – 2001
Volume 1 Assessment Report June 2003
The beach is one of the major coastal features that significantly contribute to the physical, social and economic development of Antigua and Barbuda. Between 1996 and 2001, various changes have occurred on a number of beaches. Tropical weather systems, including tropical waves, depressions, tropical storms and hurricanes, have contributed to these changes. For this period, there were four (4) tropical depressions, six (6) tropical storms and ten (10) hurricanes that may have impacted Antigua and Barbuda. This report provides a summary, including quantitative assessments of some of the changes. Volume 2 provides the detailed data and assessment of each beach-monitoring site.
The beach-monitoring programme that started in 1991 in Antigua was extended to Barbuda in 1995. Figure 1 and Figure 2 show the beaches that are monitored in Antigua and Barbuda. Twenty-five (25) beaches were measured (19 in Antigua, 6 in Barbuda). Both volumes will cover data from 1996-2001 in Antigua and from 1996-2000 in Barbuda. Previous volumes, prepared by Dr. Gillian Cambers, covered the period 1991-1995. The beaches are measured every three months but transportation and other factors have affected the regularity of measurements in Barbuda.
Figure 1. Monitored Beaches in Antigua
Figure 2. Monitored Beaches in Barbuda
Table 1. Barbuda: Beach Changes 1996-2000
Beach Change in Profile Area
Change in Profile Width
Coco Point Hotel 0.23 1.30 Gravenor Bay 0.67 1.01 Palm Beach -0.10 -0.80 Dulcina Hotel 0.18 1.32 Palmetto Hotel 1.60 5.97 Two Foot Bay 0.26 2.40 Mean 0.47 1.87
At the monitored beaches in Antigua, for the reporting period, there was an average increase in profile area of 0.63 m2 while the profile width narrowed at a rate of –0.04 m/yr. In Barbuda there was an overall increase, with average profile area and width of 0.47 m2 and 1.87 m/yr, respectively. For both Antigua and Barbuda, the profile area ranged from –12.52 m2 to 17.06 m2 while the profile width ranged from -1.39 m/yr to 5.97 m/yr. Table 1 and Table 2 show the average changes in profile area and width for Barbuda and Antigua.
There was considerable variation in profile area and width, depending on several factors including location on the island and level of development on the beach. The effects of Hurricane Luis (1995) may also be a contributory factor. Up until 1995, erosion was the dominant process on most of the beaches of Antigua and Barbuda. The post-Luis period shows a shift in that accretion became more prominent. This is normal, following a hurricane where sand removed to offshore are being redeposited on the beach. Most beaches have still not recovered fully from this hurricane.
Table 2. Antigua: Beach Changes 1996-2001
Beach Change in Profile Area
Change in Profile Width
Jabberwock Beach -1.15 -0.11 Dutchman Bay -0.57 -0.30 Long Bay -0.48 -0.25 Half Moon Bay 5.67 0.31 Mamora Bay -0.62 -0.09 Pigeon Point Beach -1.10 -0.07 Falmouth Beach 0.96 -0.08 Morris Bay 2.98 0.37 Crab Hill Bay 14.67 0.34 Darkwood Beach 2.26 0.42 Ffryes Bay -9.77 -0.53 Lignumvitae Bay 5.24 0.23 Mosquito Cove -12.52 -1.39 Yorks Beach 17.06 0.90 Stony Horn Beach 4.12 0.52 Deep Bay -6.01 -0.73 Fort James Beach -11.76 -0.21 Runaway Bay 4.10 0.46 Dickenson Bay -1.10 -0.59 Mean 0.63 -0.04
Coastal development, particularly in Antigua, continues to significantly determine the structure and configuration of the coastline. Based on past experiences, attempts have been made to maintain important coastal ecosystems, including coral reefs, sea grass beds, beaches and wetlands. Coastal development setbacks have been designed for Antigua and Barbuda but their implementation is relatively slow. A draft policy framework for the management of beaches has also been developed. In addition, critical recommendations have been made for the management of sand as a national, natural resource.
Although the beach-monitoring programme provides the mean conditions for the beaches around Antigua and Barbuda, the system can be improved if a wider variety of beaches are monitored with even greater precision and regularity. This will include the geo-referencing of the beach-monitoring sites, additional training in beach monitoring activities and the analysis of beach data, all of which will necessitate an increase of the resources of the Fisheries Division (FD). The capability of the Fisheries Office in Barbuda would need to be improved.
A project, Managing Beach Resources and Planning for Coastline Change, Caribbean Islands which started in the mid 1980s, has concentrated on developing capacity in the small islands of the Caribbean to effectively manage beach resources. Starting initially with beach erosion, the project established monitoring programmes within government agencies, NGOs and sometimes schools, so that stakeholders could understand the changes taking place on their beaches and begin to develop solutions to those problems. The challenge now facing the project is to develop ways to convince senior decision-makers of the need, indeed the necessity, to implement some hard decisions, such as controlling beach sand mining and beachfront development.
The project was formerly titled ‘Coast and Beach Stability in Lesser Antilles of the Caribbean’ and is known locally by an old acronym COSALC.
The goal of the project was "to develop in-country capabilities so that small islands of the Caribbean, particularly the Organization of Eastern Caribbean States (OECS), often economically dependent on coastal tourism, can effectively manage their changing beach resources and plan for coastline change in a framework of integrated coastal management." The initial focus was on small islands in the eastern Caribbean but recently the scope has widened to include Haiti and the San Andres Archipelago (Colombia). Dr. Gillian Cambers, firstname.lastname@example.org, was the main coordinator of the programme.
The beach-monitoring programme started in Antigua (1991) under COSALC, part of a UNESCO Coastal Marine Project replaced in 1995 by the new UNESCO programme: Environment and Development in Coastal regions and Small Islands (CSI) administered jointly by UNESCO and the University of Puerto Rico Sea Grant College Programme (UPR – SGCP). The beach-monitoring programme eventually became the full responsibility of the Fisheries Division (FD) within the Ministry of Agriculture, Lands, Fisheries of Antigua and Barbuda.
The staff of the FD, of Antigua and Barbuda, conducts Field monitoring and data analysis.1 In the earlier part of the reporting period, technical support to the programme came mainly from UPR – SGCP. Project funding was provided through the United States Agency for Internatioanl Development (USAID) and the Caribbean Development Bank (CDB).
Volume 1 of this report summarizes the data collected over the period 1996 – 2001 and follows three earlier reports published in 1993, 1994 and 1996.
Volume 2 contains the detailed data for each of the 25 monitored beaches (19 beaches in Antigua and 6 beaches on Barbuda).
These reports will provide useful information for other projects particularly related to global climate change and sea level rise. For example, it can be utilized in the Coastal Resource Inventory System (CRIS), a database created under the Caribbean Planning for Adaptation to Climate Change (CPACC) project.
Antigua has a substantial database with continuous coverage over the period 1991-2001, which includes the effects of several hurricanes and tropical storms. Barbuda’s database covers the period 1995-2000. The information can be used in coastal planning and coastal erosion mitigation.
1 The beach-monitoring activity used to be a joint activity of the Fisheries Division and the Development Control Authority (DCA). However, due to staff changes and difficulties with coordination, the involvement of the DCA ceased in 1996.
In recognition of the importance of coastal habitats, including coral reefs, sea grass beds, beaches and wetlands, to Antigua and Barbuda, the beach-monitoring programme provides critical information, which can be used in the promotion and development of wise practices within the coastal areas of Antigua and Barbuda.
Figure 3 gives a simple diagram showing the various parts of a beach. A beach can be defined as a zone of loose material extending from the low water mark to a point landward where either the topography abruptly changes or permanent vegetation first appears. Although beaches are often made up of sand particles, they may also consist of clay, silt, gravel, cobbles or boulders, or any combination of these. The particle sizes of these sediments are shown in Table 3. The monitored beaches in Antigua and Barbuda are all sandy beaches.
Figure 3. Cross-section of a Typical BeachAfter Cambers, 1996a
An analysis of the influence of tropical weather systems on the coastal landscape of Antigua and Barbuda helps to provide a greater understanding of coastal processes during specific periods.
Table 3. Sediment Sizes Clay less than 0.004 mm less than 0.00015 inches Silt 0.004–0.08 mm 0.00015–0.003 inches Sand 0.08–4.6 mm 0.003–0.18 inches Gravel 4.6–77 mm 0.18–3 inches Cobbles 77–256 mm 3–10 inches Boulders greater than 256 mm greater than 10 inches
The methodology employed during each monitoring period may be improved over time, eventually increasing the accuracy and efficiency of the process. In addition, past records and reports can indicate trends that assist in predictions for the future.
Tropical Weather Systems affecting Antigua and Barbuda
Tropical weather systems are common in the northern and eastern Caribbean, including Antigua and Barbuda, between the months of June – November, annually. Whether depression, storm or hurricane, these can affect wave motion around Antigua and Barbuda, even when they pass miles from land. Between 1996 and 2001, twenty (20) tropical weather systems have affected Antigua and Barbuda. These are indicated in Figure 4. and also listed in Appendix 1.
Figure 4. Number of Tropical Weather Systems affecting
Antigua and Barbuda 1995-2001
Except for 2001, at least one (1) hurricane occurred per year between 1995 and 2001. The years 1996 and 1999 were particularly active in terms of tropical weather system activity, each with one (1) tropical storm and three (3) hurricanes. Once there is a tropical weather system affecting the area, depending on the location and magnitude of the system, one or more of the following are likely to occur:
Iincreased erosion along beach segments, leading to narrowing of the beach (profile width decrease), less sand available (profile area decline) and the eventual loss of sand (consequently, beachrock will become exposed)
Change in the position of the dune base.
The effects of tropical weather systems can be either positive, negative or both, on the same beach depending on existing conditions of the beach and the relative characteristics of the system. There may also be monthly or annual variations in weather conditions and consequently the shoreline environment will change.
Following a tropical weather system, particularly a hurricane, beaches usually become lower and narrower. Thus, waves may be able to reach roads or buildings that were away from the active wave impact zone before the hurricane. Some beaches may be totally stripped of their sand leaving rock outcrops exposed. Rocky ledges often consisting of beachrock may become exposed where they were not evident before. Considerable quantities of beach sand have been moved inland and deposited on coastal roadways, in swimming pools and on beachfront properties. Large volumes of sand may also be moved offshore. The water depth in the offshore zone may be much shallower than before the hurricane. Sand dunes, which were previously gently sloping and covered with vegetation, will now stand at a near-vertical angle and bare of vegetation. (See Figure 5.). In small sandy bays, sometimes all the sand will have been transported to one end of the beach. The material composing the beach may have changed from sand to stones and boulders.
Figure 5. Dune retreat after a hurricane
The dune face has been eroded leaving a near vertical slope.
In the months following the hurricane, the sand will slump to
form a more stable slope (adapted from Cambers, 1995).
Past Activities Re: Beach Monitoring in Antigua and Barbuda
Previous reports for the beach monitoring programme (Black et al. 1994, 1995, 1996) showed that there were considerable variations in the data from site to site and from year to year. The data have shown that between 1992 and 1995, 9 of the 25 monitored beaches in Antigua and Barbuda (Beaches on Barbuda were not assessed prior to 1995) were showing erosion as the dominant coastal process. Erosion was more severe during times of tropical weather systems.
Following the passage of Hurricane Georges (1998), an analysis was done of beach erosion as a hazard in Antigua and Barbuda (OAS Post Georges Disaster Mitigation Project). This study has shown that monitored beaches fell within the categories given in Table 4.
Table 4. Beach Erosion Hazard 1995-1999
Rate of Coastal Change (m/yr)
Monitored Beach Very low +5.28 to +3.38 Dulcina Hotel Low +3.37 to +1.48 Two Foot Bay, Crab Hill Bay, Lignumvitae Bay Medium +1.47 to - 0.43
Gravenor Bay, Cocoa Point Hotel, Pigeon Point Beach, Mamora Bay, Falmouth Beach, Stony Horn Beach, Yorks Beach, Jabberwock Beach, Dutchman Bay, Halfmoon Bay, Darkwood Beach, Ffryes Beach, Runaway Bay
High – 0.44 to - 2.34 Morris Bay, Fort James Beach, Dickenson Bay, Low Bay, Long Bay, Deep Bay, Mosquito Cove Very high – 2.35 to - 4.25 Palmetto Hotel
Most of the monitored beaches on Antigua (17) fell within the medium to high hazard category with two being low (Crab Hill Bay and Lignumvitae Bay). The hazard categories for Barbuda ranged from the extreme of very low (Dulcina) to very high (Palmetto Point). Both technical and non-technical reports are available on the OAS website which provides more details.
As part of the CPACC Project, Antigua and Barbuda’s involvement included the development of economic instruments for enhancing coastal management. The focus was on sand management with a view of "meeting demands for sand without undermining the environmental integrity of coastal ecosystems". The programme therefore sought to manage sand as a national, natural resource, in a sustainable way.
In addition there are other beach related projects administered by different government agencies. These include the management of sand, for construction purposes, by the Ministry of Communications and Works (MCW) or Public Works and various beach cleaning and beautification activities by the Ministry of Tourism and the Environment (MTE). These projects need to be integrated into a wider coastal development plan for Antigua and Barbuda.
The FD continues to employ the same methodology developed in 1991. There are however, slight improvements in the instruments used and the computer programme utilized in data analysis. Twenty-five (25) beaches were monitored between 1996 and 2001. These included:
Dickenson Bay (4 Sites)
Runaway Bay (3 Sites)
Fort James Beach (2 Sites)
Deep Bay (2 Sites)
Stony Horn Beach (2 Sites)
Yorks Beach (2 Sites)
Mosquito Cove (1 Site)
Lignumvitae Bay (3 Sites)
Ffryes Beach (3 Sites)
Darkwood Beach (3 Sites)
Crab Hill Bay (1 Site)
Morris Bay (1 Site)
Falmouth Beach (1 Site)
Pigeon Point Beach (2 Sites)
Halfmoon Bay (3 Sites)
Long Bay (2 Sites)
Mamora Bay (1 Site)
Dutchman Bay (3 Sites)
Jabberwock Beach (2 Sites)
Gravenor Bay (1 Site)
Cocoa Point Beach (3 Sites)
Dulcina Hotel (1 Site)
Palmetto Hotel (1 Site)
Low Bay (1 Site)
Two Foot Bay (1 Site)
Measurements for beach monitoring continue every three (3) months. This provides a profile across the beach, starting from an established reference point at the back of the beach and ending in the water at the first offshore step, which usually coincides, with the wave breakpoint.
The upgraded software used in the analysis automatically generates the cross sectional area under the beach profile, adjusted to a standard vertical drop below the reference point, as well as the width of the profile. This fully-compiled software programme, entitled ‘Beach Profile Analysis,’ provides basic information for data analysis and the graphical representation of beach change trends, specifically the following:
Entry of beach profile data collected in the field;
Graphical plots of beach profiles;
Composite plots showing several profiles on the same graph;
Preparation of data tables for individual sites showing values for profile cross sectional area and profile profile width as well as annual means;
Preparation of trend graphs showing changes in profile area and width over time.
The programme has four main routines: data entry, graphical plots of the beach profiles, data tables, and trend graphs. The profiles and graphs can be easily transferred to word processing documents.
Changes in profile area are calculated in square metres (m2). First, using the quarterly values generated, the mean profile area is calculated for the base year. Then the mean for the subsequent years is calculated and averaged. The two means are then compared and the change determined. The change in profile area may be expressed as either positive or negative. A positive figure is an indication that the profile is increasing and accretion is the dominant process while a negative figure indicates a decrease in profile area or erosion.
Profile width is measured in metres (m). Changes in profile width are determined in a similar manner to changes in profile area. Following the calculation of the mean profile width for the baseline year and the mean width for subsequent years, the difference between the two mean figures is determined and divided by the number of years to give the change in profile width. This change is expressed in metres per year (m/yr). A positive change indicates accretion while a negative change shows that the profile has narrowed or eroded.
This report provides information on changes in Antigua (1996-2001) and Barbuda (1996-2000). General trends are given relative to the passage of tropical weather systems and where data is available, comparisons are made with beach changes prior to 1996.