An Assessment of Beach Erosion Hazards
in Antigua and Barbuda

OAS/USAID Post-Georges Disaster Mitigation Project

Implemented by the Organization of American States,
Unit for Sustainable Development and Environment
for USAID-Jamaica/Caribbean Regional Program

January 2001


Acknowledgements

This report was prepared by Philmore James, Antigua.


Table of Contents

INTRODUCTION
Background
Project Objectives and Outline
METHODOLOGY
Data Collection
Data Automation
Analysis
STRUCTURE AND CONTENT OF HAZARD MAPS
RESULTS AND DISCUSSION
RECOMMENDATIONS AND CONCLUSIONS
REFERENCES

APPENDICES
I. Activity Timetable
II. Data Dictionary
III. Metadata for maps
IV. Barbuda Mean Annual Beach Width
V. Antigua Mean Annual Beach Width

List of Tables

1.0 Logical Framework Analysis
2.0 Base Data for the Project
3.0 Hurricane Frequency between 1990 and 1999 in the Atlantic Basin.
4.0 Tropical Systems which affected Antigua and Barbuda between 1995 and 1999
5.0 Antigua – Mean Annual Rates of Coastal Change 1992-1999
6.0 Barbuda – Mean Annual Rates of Coastal Change 1995-1999

List of Figures

1.0 Beach Monitoring Sites: Antigua
2.0 Beach Monitoring Sites: Barbuda
3.0 Coastal Change Rates in Antigua and Barbuda

List of Acronyms

COSALC Coast and Beach Stability Project
GIS Geographical Information Systems
OAS/USDE Organization of American States, Unit for Sustainable Development and Environment
PGDM Post-Georges Disaster Mitigation
SIDS Small Island Developing State
TS Tropical Storm
UNESCO United Nations Educational, Scientific and Cultural Organization
UPR-SGCP University of Puerto Rico Sea Grant College Program
USAID-J/CAR US Agency for International Development-Jamaica/Caribbean Regional Program


Introduction

Background

Antigua and Barbuda, a Small Island Developing State (SIDS), has a fragile economy heavily dependent on coastal tourism. In addition, the country ranks high in terms of its vulnerability to tropical storms and hurricanes. Between 1995 and 1999, Antigua and Barbuda experienced four major hurricanes, which caused severe damage and loss to the natural environment and critical changes in the social and economic fabric of the country. The severe weather conditions may be related to climate variations, climate change and possible sea level rise. It is therefore critical to analyze the changes which occur around the coastal regions of Antigua and Barbuda and where possible to predict future trends in order to determine future development policy.

On 20-22 September 1998, Hurricane Georges, a category 3 storm, struck the Eastern Caribbean islands of Antigua and Barbuda and St. Kitts and Nevis causing severe damage to the economic and social infrastructure of these islands. In Antigua, the south coast of the island suffered most of the damage, with 400 homes destroyed, major damage to a number of health facilities, and a disrupted electrical supply. The tourism sector, livestock and fisheries also suffered significant losses.

In response to the damage from Hurricane Georges, the US Agency for International Development-Jamaica/Caribbean Regional Program (USAID-J/CAR), has established a program entitled Hurricane Georges Reconstruction and Recovery in the Eastern Caribbean specially targeting Antigua and Barbuda and St. Kitts and Nevis. The activity entitled Post-Georges Disaster Mitigation (PGDM) is the disaster mitigation capacity building component of the program. The PGDM is implemented by the Organization of American States' Unit for Sustainable Development and Environment (OAS/USDE) for USAID-J/CAR.

The goal of the PGDM program is to reduce the vulnerability of people and economic activities in St. Kitts and Nevis and Antigua and Barbuda to natural hazards, including tropical storms and related flooding, seismic and volcanic hazards, through enhanced capacity for hazard mitigation.

The Fisheries Division, in 1991, established a beach monitoring program within the regional ‘Coast and Beach Stability in the Caribbean Islands’ (COSALC) Project, sponsored by the United Nations Educational, Scientific and Cultural Organization (UNESCO) and the University of Puerto Rico Sea Grant College Program (UPR-SGCP). Nineteen beaches in Antigua and six in Barbuda are monitored quarterly using standard techniques to measure beach profiles; changes in the profile cross-sectional area and profile width are then determined. These data, collected for the selected beaches, along with other related physical, social and economic information will be utilized in this project to achieve the required objectives. Additionally, it is hoped that this project could become a model for other SIDS experiencing similar conditions.

This project focuses primarily on beach changes and the various causal factors which operate within the beach zone. The impact of hurricanes, storms and different human-induced activities will also be discussed.

Project Objectives and Outline

One of the major objectives of the PGDM project of the Organization of American States, is the development of national goals, objectives and actions to reduce the vulnerability of Antigua and Barbuda to natural hazards. A prerequisite for appropriate hazard mitigation strategies is a solid understanding of the existing hazards and their effects. Under this contract, an assessment of coastal erosion hazards will be undertaken for the islands of Antigua and Barbuda. The improved understanding of these hazards will inform national coastal development and erosion hazard vulnerability reduction policies and measures for Antigua and Barbuda.

Under this contract, a hazard assessment of coastal erosion in Antigua and Barbuda was undertaken, using current coastal erosion hazard assessment methodologies. The main outputs include the production of a technical report and a non-technical summary of the coastal erosion hazard assessment for Antigua and Barbuda. The technical report describes the structure and content of the hazard maps, the methodology employed in map preparation, including data collection, analysis and final preparation, map use and limitations, metadata and information sources and guidance on understanding coastal erosion hazards. Recommendations for future work are also included. This report also identifies key contacts in Antigua and Barbuda for coastal erosion hazards.

The non-technical summary of the erosion hazard assessment for Antigua and Barbuda has been prepared for the layman and may be distributed independent of the technical report.

Apart from the demonstration of current geographical information systems (GIS) and other techniques that may be applied in the analyses, major objectives of this project include:

The logical framework analysis, shown in Table 1.0, gives an overview of the project. The general outline of activities and the time schedule are shown in Appendix I.

The major constraints of this project include the following:

Figures 1.0 and 2.0 provide maps showing coastal erosion hazards along the beach-monitoring sites of Antigua and Barbuda. The rates of coastal change are shown graphically in Figure 3.0.

TABLE 1.0 LOGICAL FRAMEWORK ANALYSIS

 

Objectively Verifiable Indicators

Means of Verification

Important Assumptions

GOAL:

Assess beach changes around Antigua and Barbuda

 

Beach width

Hurricanes/storms

 

Actual changes in beach width

 

Beach changes are caused by specific factors

PURPOSE:

Identification of beach changes around Antigua and Barbuda

 

Changes in beach width

Hurricane/storm occurrences

Other coastal activities

 

Changes in relation to Storms/hurricanes and other

coastal activities

 

Specific causes of beach changes can be identified based on periods when storms are dominant

INPUTS:

Beach monitoring

Data collecting

Data processing

Equipment and supplies

Project management

 

Monitoring of specific beaches

Actual data (beach, hurricane, sand mining)

Actual equipment and supplies

A successful (completed) project

 

Working GIs project, including equipment, personnel and a database

 

Apart from the data used (causes), other factors are minimal in determining beach changes

OUTPUTS:

Information (coastal data)

Working GIS program

Maps

Reports

Recommendations

Management 0ptions

 

Changes (width) due to hurricanes and storms

Changes due to other activities such as sand mining and coastal development

Actual report with recommendations and management options

 

Actual data sets

Maps produced

Reports written

 

Beach width show the major beach changes

During a storm, beach changes are due only to storm effects.

Other Factors dominate beach changes outside of hurricane periods.

 

Figure 1.0 Coastal Erosion Hazard: Antigua

Figure 1.0

Figure 2.0 Coastal Erosion Hazard: Barbuda

Figure 2.0

Figure 3.0 Coastal Change Rates: Antigua and Barbuda

Methodology

Several methods and techniques were used in developing this project, including surveying beach profiles, analysis of the beach data, and the use and application of various GIS computer hardware and software. The following activities are included in this hazard assessment work:

Data Collection

Table 2.0 outlines the nature, format and source of data that was used in the project. The basic activities include:

Beach monitoring was started in Antigua in 1991, thirteen beaches on the west, south and east coasts were selected for monitoring (Cambers, 1991). The selection included beaches showing the following characteristics:

Table 2.0 Base Data for the Project

 Base Data

Availability And Format

Source(s)

Digital

Non-digital

Beach data (width)

 

X

Fisheries

Hurricane data

 

X

Met. Office, www

Coastline, beach outline

X

 

PGDM Project

Hydrology: rivers, streams, watercourses, ponds

X

 

PGDM Project

Topography/contours

X

 

PGDM Project

Wetlands and other sensitive sites

X

 

PGDM Project

Location of major settlements

X

 

PGDM Project

Fisheries: Fisheries Division
Met. Office: Meteorological Office
www: World Wide Web

At most beaches, more than one profile site was established. In 1994 six additional beaches were added to the list of those monitored. Profiles are measured quarterly from fixed reference points located behind the beach, using Abney levels, ranging poles and tape measures, and the profiles terminate at the offshore step. The data are then plotted and analyzed using a custom-designed computer program; outputs include profile width and profile cross sectional area.

Beach monitoring was started in Barbuda in 1995, six beaches were selected for measurement, using similar selection characteristics as for Antigua, although in the case of Barbuda, the final selection was governed by accessibility to the site. Beach monitoring in Barbuda is undertaken with the assistance of the Coastguard, and is usually done between two and four times a year.

The Beach Profile Analysis Program was used to calculate average annual profile cross- sectional area and profile width. It was decided to use the profile width parameter as an indicator of the erosion hazard for this project, mainly because it is relatively easy to understand, e.g. if the profile width decreases over time, then the beach is eroding and the erosion hazard is greater than a profile where the width is increasing over time. For this analysis, the average profile width at a particular site for the first year of measurement was compared with the same parameter for the last year of measurement, and the difference between the two figures was divided by the number of years of measurement to provide a rate of coastal change in meters/year. However, it is recognized that more comprehensive erosion hazard indicators could be developed in the future.

The beach-monitoring program in Antigua and Barbuda concentrates on sandy beaches since these are of vital economic importance to the tourism industry. Rates of change on rocky and cliffed shorelines have not been measured, but it is likely that they are considerably lower than those pertaining to sandy beaches in Antigua and Barbuda. Although in the case of cliffs, erosion is not usually a gradual process, but a sudden one, as large blocks collapse especially in fractured rocks such as limestone, see Cambers (1998) for a more complete discussion.

Data Automation

Using the GIS layers provided by the PGDM project as a base, new layers were created to show

beaches that are monitored/not monitored. All digitizing was done on screen. Categorization was done to show the varied beach erosion hazards throughout Antigua and Barbuda. Based on the information, maps were produced at a scale of 1:50,000.

The equipment utilized during the project include desktop computers, inkjet printers and a plotter while ArcView 3.1 was the main GIS software. MS Word 97 and MS Access 97 were used for word processing and data processing respectively.

Analysis

Using the beach monitoring and other data, major operational processes and activities were determined so that beaches affected by storms or other factors were identified. A coastal erosion hazard index was developed for the various beaches that are monitored around Antigua and Barbuda. The categories for the erosion hazard index are derived using the equal interval/class method. The rates of coastal change in Antigua and Barbuda were grouped and the range between the highest and the lowest erosion rate was determined. The range was then divided by the number of categories, which had been predetermined as five. The limits of each category were then determined as shown below:

Rate of Coastal Change Hazard category [m/yr]

+3.38 to +5.28 Very low
+1.48 to +3.37 Low
- 0.43 to +1.47 Medium or Moderate
- 2.34 to – 0.44 High
- 4.25 to – 2.35 Very high

The maps depict the hazard category for an individual beach or segment of the beach. At some beaches where there are several profile sites, it was observed that some segments of a particular beach might behave differently to others. For instance, at Runaway Bay, the northern profile site showed erosion, while the central and southern profile sites showed accretion. In cases such as this, where the particular bay was longer than 500 m, the beach was divided into two segments for the purposes of mapping. However, where a particular bay was very short, and a similar differentiation was observed, the map scale was too small to show this difference, and in such cases, an average coastal change rate was calculated for the bay and mapped. (This was the case for Stony Horn, Yorks Bay and Long Bay).

Structure and Content of the Hazard Maps

Together with the reports the hazard maps for Antigua and Barbuda form the main output of this project. The maps show erosion hazards for the various monitored beaches around Antigua and Barbuda. The base map was produced from overlays provided by the PGDM project. These include contours, roads, settlements and critical coastal habitats. The maps are drawn at a scale of 1:50,000.

The maps are entitled: Coastal Erosion Hazard: Antigua/Barbuda and the hazard categories are shown in color for easy reference and contrast. For Antigua the relative hazards are shown as low, moderate or high, while for Barbuda, where there is a greater range in the data, there are two additional categories: very low and very high, these show relatively extreme conditions.

Most of the map sheet is covered by the actual map which is accompanied by an illustrated legend. Apart from the various established symbols shown on the map the legend seeks to explain the meaning of the relative rankings in both quantitative and qualitative terms.

There is a caption indicating the suggested usage and limitations of the maps. These maps should only be used for the purpose of coastal erosion hazard analysis and not for all hazards since there are major limitations. The information is based only on changes in beach width. Using the given erosion rates, predictions regarding the erosion hazard can be made, although a longer time series would produce more accurate results. Without scientific evidence and reliable data, unmonitored beaches have not been ranked for erosion hazard, although various qualitative observations exist for some of these unmonitored beaches. The maps therefore do not indicate the erosion risk for beaches that are not monitored.

For up to date information on the state of the coastal areas of Antigua and Barbuda contact:

Fisheries Division
Ministry of Agriculture, Lands, Fisheries
Perry Bay
St. John’s
Antigua W.I.
Tel./Fax: 1-268-462-1372
Email: fisheries@candw.ag

The logos of the sponsors or implementing agencies (USAID and OAS) are also placed on the maps. For additional information the PGDM website is given as the main contact for the project. This is shown as http://www.oas.org/pgdm.

Results and Discussion

Available data show that the number and intensity of tropical storms is on the increase. Table 3.0 clearly shows that the number of named storms has increased over the last five year period (55 %) as compared with the previous five year period (1990-1994), and the number of hurricanes per year has increased by 78 %. For the same period the number of hurricane days per year trebled while the number of category 3, 4 or 5 hurricanes quadrupled. Antigua and Barbuda experienced four major tropical systems during the past five years. Several beaches have changed their shape and character as a result.

Table 3.0 Hurricane Frequency Between 1990 and 1999 in the Atlantic Basin

Five Year Period

No. Named Storms

No. Hurricanes Per Year

No. Hurricane Days Per Year

No. Category 3, 4, 5 Hurricanes Per Year

1990 – 1994

8.4

4.6

13.6

1

1995 – 1999

13.0

8.2

41.4

4.0

Source: http://typhoon.atmos.colostate.edu/forecasts/1999/nov99/

Table 4.0 shows the major tropical systems that affected Antigua and Barbuda between 1995 and 1999. Four of the systems made landfall. Apart from the direct effects of hurricane winds, storm surges also impacted the coastline. At the monitored beaches, the changes in beach area and width result from a combination of factors including hurricane impacts.

Table 4.0 Tropical Systems which affected Antigua and Barbuda between 1995 and 1999

Name

Category

Wind Speed (km/hr

Track Location Location

Date

Iris

TS

93

South

27-Jul-95

Luis

4

222

Landfall

09-Sep-95

Marilyn

1

148

North

15-Sep-95

Bertha

1

139

South

07-Aug-96

Hortense

1

130

North

09-Oct-96

Erika

1

130

North

09-Jun-97

Georges

3

185

Landfall

21-Sep-98

Jose

2

157

Landfall

20-Oct-99

Lenny

TS

102

Landfall

20-Nov-99

Note: Wind speeds are for the direct time of passage over Antigua and Barbuda

Analysis of the coastal change rates along the monitored beaches of Antigua (see Table 5.0) indicates that erosion is the dominant process on nine beaches while the other nine show accretion. Six of these beaches show marked variations along their length, in that erosion and accretion dominate on different segments of the beach. (As discussed in the Methodology section, a similar variation was seen in three very short beaches: Stony Horn, Yorks Bay and Long Bay, but this variation could not be mapped because of scale limitations). Where there is variation between the different beach segments, erosion tends to dominate along the northern end of the beach, and accretion at the southern end.

As shown in Table 5.0, most of the monitored beaches on Antigua (16) fall between the medium to high hazard category with one in the medium to low (Ffryes) and two that are fully low (Crab Hill Bay and Lignumvitae Bay).

Table 5.0 Antigua – Mean Annual Rates of Coastal Change 1992 - 1999

Beach

Mean annual coastal change rate (m/yr)

Hazard category

Dickenson Bay

-2.01

High

Runaway Bay North

-0.37

Medium

Runaway Bay South

0.71

Medium

Fort James

-0.50

High

Deep Bay

-0.55

High

Yorks Bay

0.59

Medium

Stony Horn Bay

0.21

Medium

Mosquito Cove

-1.47

High

Lignumvitae Bay

2.16

Low

Ffryes Bay North

-0.31

Medium

Ffryes Bay South

1.68

Low

Darkwood Bay North

-0.67

High

Darkwood Bay South

0.52

Medium

Crabhill Bay

1.49

Low

Morris Bay

-0.71

High

Falmouth

0.90

Medium

Mamora Bay

-0.14

Medium

Pigeon Point

0.30

Medium

Halfmoon Bay North

-0.70

High

Halfmoon Bay South

0.19

Medium

Long Bay

-0.47

High

Dutchman Bay North

-0.34

Medium

Dutchman Bay South

0.66

Medium

Jabberwock North

-0.74

High

Jabberwock South

0.77

Medium

There was no clear pattern between the rate of beach change and the coastline orientation. The beaches on the northeastern side of the island tend to show overall accretion. This is noticeable for Jabberwock and Dutchman Bay. Although these beaches are open to winds directly off the Atlantic Ocean the effects are minimized by the presence of offshore reef systems. Furthermore at Dutchman Bay, an offshore breakwater provides additional protection. Similar reef protection exists at Halfmoon Bay and Mamora Bay, however, these beaches show overall accretion. On the south coast, Pigeon Point and Falmouth Beach show some accretion, this may be due to their sheltered nature within Falmouth Harbour. Morris Bay falls within the high hazard category, possibly a result of the open nature of the bay combined with the narrow shelf providing deep water conditions close inshore, which will increase exposure during storm events.

Along western Antigua, accretion dominates at Crab Hill Bay, Ffryes Bay, Lignumvitae Bay, Stony Horn and Yorks Bay. Most of these beaches are relatively open, although in the case of Lignumvitae Bay, T-shaped groynes may be playing a role in the accretion process. The more sheltered Mosquito Cove differs markedly in that like Darkwood Beach erosion tends to dominate. At Darkwood this may be due to the long-term effect of sand mining, while at Mosquito Cove it could be the combined impact of sand mining and harbour dredging.

The northwestern shore of Antigua has one of the highest levels of coastal tourism development. Beaches here show relatively high rates of erosion particularly along Dickenson Bay, which together with Deep Bay and Fort James show high erosion hazard. Runaway Bay falls within the moderate erosion hazard category, although it should be noted that the northern end of this beach showed very severe erosion, which started the year after Hurricane Luis (1996).

Although storm impacts are emphasized in this report, other factors play major roles in determining the erosion/accretion rates along the beaches around Antigua. The role of development too close to the coastline, sand-mining, dredging, coastal protection structures, beach orientation, and relief of nearby landscape should never be underestimated. The average annual width of monitored beaches over the period 1992-1999 on Antigua is shown in Appendix IV, and for Barbuda over the period 1995-1999 in Appendix III. An increase in the number of sites as well as the number of beaches monitored, in Antigua and Barbuda, would increase the database and the accuracy of the analysis.

In the case of Barbuda with its flat, low-lying landscape there is an even greater contrast in the rates. Of the six beaches monitored on Barbuda two (Two-Foot Bay and Dulcina) clearly show accretion as the dominant process while erosion is more significant for two others (Palm Beach and Palmetto Point). The different sectors of Coco Point, a long spit, tend to vary, with accretion dominant in the north whereas the peninsular in the south is eroding.

As depicted in Table 6.0, the hazard categories for Barbuda range from the extreme of very low (Dulcina) to very high (Palmetto Point). Palmetto Point is a large sandy promontory with an extensive array of sand dunes. Such promontories, like spits, are unstable and tend to move, sometimes dramatically. On the other hand the presence of an extended jetty at the River (near to Dulcina) could cause a build-up of sediments along the adjoining coastline. Palm Beach is located on a narrow sand bar enclosing the Codrington Lagoon, storms and hurricanes frequently

Table 6.0 Barbuda – Mean Annual Rates of Coastal Change 1995 - 1999

Site

Mean annual coastal change rate (m/yr)

Hazard Category

Gravenor Bay

0.189

Medium

Cocoa Point A

-0.211

Medium

Cocoa Point B

2.916

Low

Cocoa Point C

-1.862

High

Dulcina

5.278

Very Low

Palmetto Point

-4.25

Very High

Palm Bay

-1.816

High

Two Foot Bay

2.689

Low

cut through this bar. In spite of surrounding coral reefs, Coco Point is changing rapidly, the southern end of the spit is eroding, and accretion is occurring at the northern end. In the northeast, Two Foot Bay, which is exposed to the Atlantic Ocean, shows accretion and a low erosion hazard rate. This may be partly due to the fringing reefs along the northeastern coast of Barbuda.

In reference to the effects of tropical systems on the coastal areas of Antigua and Barbuda, various reports have shown that with the passage of a tropical storm or hurricane the rate at which coastal activity occurs tend to increase. (Black et. Al, 1996a, 1996b; Cambers 1993, 1996a, 1996b). Beaches therefore may show both seasonal and long-term changes as winds interact with waves, tides and currents. Erosion and deposition are the basic manifestations of beach change. The impact of hurricanes on beaches is significant since wind speed and direction are critical controlling variables of wave action.

While the relationship between the proximity of a hurricane center and the amount of beach erosion is essential, other factors that influence the severity of erosion must be analyzed. These include the characteristics of the particular hurricane, coastline shape, width of the offshore shelf and the presence of local features such as coral reefs. A more broad-based study may be needed to show a comparison between the effects of these factors and that of tropical systems on the coastline of Antigua and Barbuda.

Recommendations and Conclusions

Based on the nature and importance of the coastal landscape of Antigua and Barbuda, especially the beaches, there is a need to develop strategies to cope with the erosion hazard vulnerability. The following measures should be considered for the future:

Following the completion of this project, some useful suggestions were received from Dr. Cassandra Rogers of the University of the West Indies, relating to ways to enhance the coastal hazard mapping in St. Kitts and Nevis, and in Antigua and Barbuda, as well as in other such studies in different islands in the future. It was pointed out that the maps show the beach erosion hazard only, not the coastal erosion hazard, which would include other factors such as cliff erosion and changes in low rocky shores. However, quantitative data are not available for these sections of coastline. While additional information relating to the nature of the un-monitored coast, e.g. whether it consist of cliffs, beaches or other coastal forms, would be useful to the map user, this should be produced as an additional map, since it would complicate the beach erosion hazard maps. It was recommended that in future studies in other islands, alternatives to the equal interval method for determining the hazard categories should be considered. The beach change data sets are very small (25 beaches measured over 7 years in Antigua and 8 beaches measured over 4 years in Barbuda), and not sufficiently robust for this method, since adding one new beach with an extreme erosion/accretion rate would change the hazard rating dramatically. Furthermore, the beach erosion hazard categories of high, medium, low etc. determined by the equal interval method, have different ranges in each island thereby reducing the opportunity for inter-island comparison.

However, despite its obvious limitations, this present analysis can be used to inform the development of national coastal development policies and measures to reduce the vulnerability to coastal erosion hazards.

References

Black D. Et al.,. 1996a. Analysis of Beach Changes in Antigua and Barbuda between 1992 and 1995 COSALC Report Volume 1, Assessment Report. Coast and Beach Stability In the Lesser Antilles, University of Puerto Rico, Sea Grant College Program, Mayaguez, Puerto Rico.

Black D. Et al.,. 1996b. Analysis of Beach Changes in Antigua and Barbuda between 1992 and 1995 COSALC Report Volume 2, Data Report. Coast and Beach Stability in the Lesser Antilles, University of Puerto Rico, Sea Grant College Program, Mayaguez, Puerto Rico.

Cambers, G. 1991. Antigua Coastal Monitoring Programme Field Manual. Report prepared for the UNESCO COMAR COSALC I project. 39 pp.

Cambers, G. 1993. Assessment of the Vulnerability of Coastal Areas in Antigua and Nevis to Sea Level Rise in , Manl. George, A. "Climate change in the Intra-Americas Sea", UNEP, 1993.

Cambers, G. 1996a. Hurricane Impacts on Beaches in the Eastern Caribbean Islands, 1989-1995. COSALC Coast nd Beach Stability in the Lesser Antilles. UNESCO Coast and Small Islands and the University of Puerto Rico Sea Grant College Program, Mayaguez, Puerto Rico. .

Cambers, G. 1996b. Methodology for Coastal Development Setbacks, COSALC I, Coast and Beach Stability In the Lesser Antilles, University of Puerto Rico, Sea Grant College Program, Mayaguez, Puerto Rico.

Cambers, G. 1998. Planning for coastline change. 1. Coastal development setback guidelines in Antigua and Barbuda. Prepared for UNESCO Environment and Development in Coastal Regions and Small Islands and the University of Puerto Rico Sea Grant College Program. 63 pages.


APPENDICES

Appendix I: The Activity Timetable: November 2000 – January 2001

[The activity timetable is not included in this version of the report.]

Appendix II: Data Dictionary

FolderName

FileName / Type

Content /Attribute

Feature Type

Antigua

Shape Files

 

 

 

Beach.shp

Beaches

Point

 

Coast.shp

Coastlines

Polygon

 

Contour.shp

Contours

Line

 

Corals.shp

Coral Reefs

Polygon

 

Watercourse.shp

Drainage

Line

 

Ponds.shp

Water Bodies

Polygon

 

Mangrove.shp

Mangroves

Polygon

 

Beach_Ant.shp

Monitored Beaches

Line

 

Road.shp

Roads

Line

 

Settlement.shp

Settlements

Polygon

 

An_unmon.shp

Unmonitored Beaches

Line

 

Arcview Project Files

 

 

Antigua

antigua_pgdm.apr

(Antigua PGDM)

 

 

bmon.apr

Arcview Project (Antigua Beach monitoring Sites)

 

 

Documents,database, Spreadsheets

 

 

Other

Beach

Beach Database

 

 

PGDM.doc

Final Project Document

 

 

FolderName

FileName / Type

Content /Attribute

Feature Type

Barbuda

Shape Files

 

 

 

Beach.shp

Beaches

Point

 

Barcoast.shp

Coastlines

Polygon

 

Barconto.shp

Contours

Line

 

Barponds.shp

Water Bodies

Polygon

 

Barmangr.shp

Mangroves

Polygon

 

Beach_Bar.shp

Monitored Beaches

Line

 

Barroad.shp

Roads

Line

 

Bar_unmon.shp

Unmonitored Beaches

Line

Barbuda

Arcview Project Files

 

 

 

barbuda_pgdm.apr

Arcview Project (Antigua PGDM)

 

 

barmon.apr

Arcview Project (Antigua Beach monitoring Sites)

 

Most of the information were received as secondary data. However, the following information refers to the original Source Map:

Scale 1:25,000
Number of sheets 2
Contour interval 25ft and 100ft
Grid British West Indies
Projection Transverse Mercator
Spheroid Clarke 1880 (Modified)
Unit of Measurement Metre
Meridian of Origin 62 West of Greenwich
Latitude of Origin Equator
Scale factor at Origin 0.9995
False Coordinates of Origin 400,000 m Easting; Nil m Northing
Year published 1962

Appendix III: Metadata for Maps

Metadata for Coastal Erosion Hazard Data: Antigua | Barbuda

Appendix IV: Barbuda Mean Annual Beach Width 1995-1999

Site

1995

(m)

1996

(m)

1997

(m)

1998

(m)

1999

(m)

Coastal change rate m/yr

Governor Bay

14.389

10.038

14.746

12.467

15.144

0.189

Cocoa Point A (K Club)

34.945

29.422

29.588

32.993

34.1

-0.211

Cocoa Point B (Hotel Cottage Wall)

 

48.044

56.314

60.716

56.793

2.916

Cocoa Point C (Hotel)

 

65.889

62.891

46.12

60.302

-1.862

Dulcina

38.163

50.288

49.352

48.221

59.275

5.278

Palmetto Point

 

52.011

109.302

114.235

39.261

-4.25

Palm Bay

34.372

28.294

25.814

26.052

27.107

-1.816

Two Foot Bay

39.415

 

42.799

45.947

61.31

62.845

2.689

Hazard Categories:

Rate of Hazard category Coastal Change (m/yr)

+3.38 to +5.28 Very low
+1.48 to +3.37 Low
- 0.43 to +1.47 Medium/Moderate
- 2.34 to – 0.44 High
- 4.25 to – 2.35 Very high

 

Appendix V: Antigua Mean Annual Beach Width 1992-1999

Site

1992 (m)

1993 (m)

1994 (m)

1995 (m)

1996 (m)

1997 (m)

1998 (m)

1999 (m)

Coastal change rate (m/yr)

Dickenson Bay A (North)

32.827

30.159

30.359

32.714

28.344

25.531

29.791

26.576

-0.314

Dickenson Bay B

18.192

14.933

17.945

18.251

33.409

26.077

31.116

24.876

-1.412

Dickenson Bay C

13.457

12.108

10.839

11.452

26.874

22.788

18.091

 

24.164

-2.157

Dickenson Bay D

22.889

10/054

20.959

15.164

18.674

12.375

8.934

 

-3.241

Dickenson Bay E (South)

29.922

26.073

24.052

26.371

16.577

15.188

 

 

-2.947

Runaway Bay A (North)

19.192

16.768

17.708

21.257

19.699*

14.399

17.060

15.035

-0.371

Runaway Bay B

26.455

24.488

25.265

23.644

30.147

31.592

31.187

29.78

0.475

Runaway Bay C (South)

30.311

25.394

26.211

30.106

35.308

40.014

39.399

36.961

0.950

Fort James A (North)

27.988

21.999

27.363

25.716

62.544

57.196

63.656

59.523

-0.877

Fort James B (South)

22.719

20.851

25.419

23.185

48.368

48.672

47.882

47.214

-0.115

Deep Bay A (North)

18.647

17.483

18.417

18.193

50.929

43.759

43.039

45.134

-1.042

Deep Bay B (South)

29.296

28.042

29.157

29.641

48.118

45.185

45.789

47.479

-0.049

Stony Horn A

 

 

18.617

16.923

12.993

15.198

15.016

15.149

-0/694

Stony Horn B

 

 

19.060

18.588

26.57

29.257

27.260

32.590

1.110

Yorks Bay A

 

 

27.680

30.286

32.663

31.865

34.001

35.938

1.652

Yorks Bay B

 

 

23.480

25.064

24.135

21.068

18.002

40.112

43.235

-0.471

* Some estimation involved at this site because the reference point was lost several times in 1996 due to erosion.

 

 

Site

1992 (m)

1993 (m)

1994 (m)

1995 (m)

1996 (m)

1997 (m)

1998 (m)

1999 (m)

Coastal change rate (m/yr)

Mosquito Cove

 

 

35.140

31.408

31.988

30.885

31.313

27.782

-1.472

Lignumvitae Bay A (North)

 

 

63.159

63.401

72.856

72.113

69.685

75.390

2.446

Lignumvitae Bay B

 

 

18.699

21.519

29.460

32.641

39.52

48.947

6.056

Lignumvitae Bay C

 

13.890

10.747

11.071

 

 

 

 

-1.410

Lignumvitae Bay D (South)

 

 

 

20.383

30.956

21.557

27.322

26.528

1.536

Ffryes Bay A (North)

33.497

31.593

28.418

28.612

76.298

67.499

71.617

71.684

 

-0.347

Ffryes Bay B

20.711

18.049

19.667

24.273

65.513

66.203

63.043

58.792

60.009

-0.277

Ffryes Bay C (South)

50.901

49.039

50.787

44.809

66.507

59.431

51.638

62.67

1.680

Darkwood Bay A (North)

39.395

34.224

35.280

30.510

23.262

22.299

23.919

30.244

-0.730

Darkwood Bay B

17.467

19.778

19.665

16.634

40.249

28.485

35.075

38.800

36.769

-0.616

Darkwood Bay C (South)

28.914

29.473

29.688

30.903

39.210

32.605

32.480

32.554

0.520

Crab Hill Bay

23.369

25.399

27.698

24.162

30.228

27.429

29.663

29.521

1.490

Morris Bay

19.950

17.513

19.502

17.414

12.726

14.160

13.676

15.014

-0.705

Falmouth Bay

24.522

28.704

29.021

30.013

33.341

34.070

32.752

30.829

0.901

Mamora Bay

 

10.728

12.197

10.519

10.552

10.085

9.876

9.884

-0.141

Pigeon Point A

31.020

30.662

30.976

28.097

34.077

33.981

33.894

32.206

0.169

Pigeon Point B

19.520

22.760

21.638

22.290

21.423

23.787

19.595

22.577

0.437

 

 

Site

1992 (m)

1993 (m)

1994 (m)

1995 (m)

1996 (m)

1997 (m)

1998 (m)

1999 (m)

Coastal change rate (m/yr)

Halfmoon Bay A (North)

44.555

34.015

38.429

40.231

38.997

39.912

31.222

39.560

-0.713

Halfmoon Bay B (Central)

33.909

30.863

30.983

36.193

35.797

35.448

36.551

34.826

0.131

Halfmoon Bay C (South – Hotel)

24.676

17.419

25.019

26.621

26.152

24.698

23.551

26.448

0.253

Long Bay A (East)

18.921

16.207

18.223

19.283

27.485

19.997

20.743

31.528

 

29.681

-1.371

Long Bay B (West)

23.017

22.529

24.009

24.533

27.883

28.214

24.686

26.054

0.434

Dutchman Bay A (North)

 

 

27.015

23.276

23.622

26.380

29.274

26.831

27.774

0.083

Dutchman Bay B

 

 

25.234

26.414

37.264

22.925

23.048

21.414

-0.764

Dutchman Bay C (South)

 

 

16.776

21.489

17.649

17.242

14.730

20.049

0.655

Jabberwock A (North)

29.794

27.447

38.157

32.986

35.056

37.625

31.933

47.753

40.380

-0.744

Jabberwock B (South)

27.653

24.529

30.336

27.399

36.348

37.030

32.435

33.057

0.772

Hazard Categories:

Rate of Hazard category Coastal Change (m/yr)

+1.48 to +3.37 Low
- 0.43 to +1.47 Medium/Moderate
- 2.34 to – 0.44 High