St. Kitts/Nevis Beach Erosion Hazard Zone Data

Shapefiles showing coastal erosion hazard zones in St. Kitts and Nevis have been created as part of the Coastal Erosion Hazard Mapping component of the OAS/USAID Post-Georges Disaster Mitigation (PGDM) Project - St. Kitts and Nevis. These files are available as a zip archive: bcherosz.zip.

Components of the shapefiles are list in Table 1.

Table 1: Beach Erosion Hazard Zone Shapefiles Components

 

Beach Erosion Hazard Zone Shapefile Components

Description

St. Kitts

skb_bchhazzone.shp

Geometry file

skb_bchhazzone.shx

Index file

skb_bchhazzone.dbf

Database file

skb_bchhazzone.avl

Legend file

Nevis

nev_bchhazzone.shp

Geometry file

nev_bchhazzone.shx

Index file

nev_bchhazzone.dbf

Database file

nev_bchhazzone.avl

Legend file

Steps for viewing shapefiles as a theme using ArcView GIS (version 3.0 or higher):

  1. Create a new directory. E.g. <C:\OASProject>.
  2. Extract and copy all shapefiles to this directory. The associated legend files (.avl) stores ArcView legend format for the beach erosion hazard zone theme.
  3. Run ArcView and open a new project.
  4. Using the add theme button, navigate to the directory created in (a) and add shapefiles- "skb_bchhazzone" and/or "nev_bchhazzone".

Creation of Beach Erosion Hazard Zone Shapefiles

In this approach, the Beach Erosion Hazard Zone Shapefiles were created as buffer areas around beach segments on shapefiles (St. Kitts-"skb_coast.shp" download; Nevis-"nv_coast.shp" download) which show relative beach erosion hazard rankings. The buffer tool in ArcView GIS (www.esri.com) was used to perform this task. The setback distances for these hazard zones/buffers were estimated using the following equation.

Hazard Zone (Hazzone_PP) = EV + ER * PP + Ero_sl

EV- the maximum or extreme beach width retreat/change(m) associated with a worse case storm. In St. Kitts, extreme beach width data is available for only one Hurricane (Luis) while Nevis has datasets for two hurricanes (Hugo and Luis). NB: the two data datasets in Nevis will be averaged. Where there are data gaps, EV is assigned zero.

PP - the planning period (years)- time span associated with the useful life of a structure. A 50 year period was be assumed.

Ero_sl - beach erosion due to relative sea level rise (m) over period PP.

ER - Long term beach erosion trend due to sediment budget considerations (m/yr). Generally, very little information is available on sediment budget for beaches and sediment budget analysis is beyond the scope of site investigation that is currently done. For this calculation, the annual beach erosion is used for ER. In cases where annual erosion rate values are positive, ER is assigned zero.

Additional Information
Shapefile name: skb_bchhazzone.shp and nev_bchhazzone.shp

Originator: Edsel B. Daniel, Box 1625, Station B, Nashville, TN 37235, U.S.A, ebdaniel@hotmail.com

Creation_Date: May 02, 2001.
Online_Linkage: St. Kitts and Nevis shapefiles (zip archive 42k)
 
Key attributes created:
 

Field Name

Field Type

Field Width

Decimal Places

Units

Field Description

Id

Integer

2

NA

NA

Identification number assigned by originator.

Beach_Name

Character

 

NA

NA

Assigned beach name.

Beach_Code

Character

3

NA

NA

Unique beach code assigned by originator.

MABC

Real

6

2

Meters per year

Mean annual beach change rate. Calculated from beach rate change data collected under the UNESCO+-COSLAC^ project.

EV

Real

6

2

Meters

Extreme values (EV) for beach recession due to Hurricane. Taken from Cambers (1996): Hurricane Impact on Beaches in the Eastern Caribbean Islands: 1989-1995.

PP

Integer

3

0

Years

Planning Period.

ER

Real

6

2

Meters per year

Erosion rate values. Negative values of MABC.

REC

Real

6

2

Meters

Projected erosion based on COSALC beach change rate (ER) values. = ER x PP. Where ER > 0, REC is assigned zero.

S_Lev_R

Real

6

2

Meters per year

Project sea level rise. Based on IPCC#, sea level rise projections 0.09 - 0.88 meters(average- 0.79m) over period: 1990 -2100. 0.79m/110 yrs = 0.007 m/yr

Ero_sl

Real

6

2

Meters

Projected erosion rate due to sea level rise

= S_Lev_R x (100)* x PP.

*The IPCC reports that 1 cm rise in sea level erodes beaches about 1 m horizontally.

Hazzone_50

Real

6

2

Meters

Hazzone_PP = EV + Rec + Ero_sl; where PP= 50, 40, 30, and 20 years. NB: Hazzone_50 values were used to create the erosion hazard zones. Hazzone_40, Hazzone_30 and Hazzone_20 values were added for reference.

Hazzone_40

Real

6

2

Meters

Hazzone_30

Real

6

2

Meters

Hazzone_20

Real

6

2

Meters

+ UNESCO United Nations Educational, Scientific and Cultural Organization.

^ COSALC Coast and Beach Stability in the Caribbean

# Intergovernmental Panel on Climate Change (www.ipcc.ch)


USAID/OAS Post-Georges Disaster Mitigation: http://www.oas.org/pgdm

Page last updated on 20 Sep 2001