Transcript Coastal Zone - Summary of hazards and vulnerabilities

UN-ECLAC Disaster
Assessment Methodology
The Coastal Zone:
Hazards to the Coastal Areas of
Caribbean SIDS
Presented by
David A.Y. Smith, Ph. D. P.Eng.
Managing Director, Smith Warner International Ltd.
Hazards affecting the Caribbean
ECLAC Disaster Assessment
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Objectives
Primary objectives of this session are:

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·
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To give an overview of the various hazards that can affect
the Caribbean region in general.
To provide some indication of the consequences of these
hazards, their frequencies of occurrence and some historic
patterns of impact.
To promote a better understanding of the mechanisms
underlying these hazards.
To set the stage for the necessary reconstruction efforts and
for mitigation of future damage.
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Profile of the Caribbean and its
Coastal Areas

Can be divided into
Greater Antilles/Lesser
Antilles – based on
location and geological
origin
 All islands have high
coastline to area ratios,
and are therefore
particularly vulnerable to
coastal hazards.
 There are differing levels
of risk across the whole
Caribbean basin.
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Coastal Hazards in the
Caribbean

Over 6000 lives lost in the Caribbean over past
30 years due to natural disasters.
Greater Antilles
Lesser Antilles
(Cuba, Jamaica,
Hispañola, Puerto Rico)
(St. Maarten to Trinidad)
•Hurricanes
•Hurricanes
•Floods
•Volcanic Eruptions
(Ash fallout)
•Earthquakes
•Earthquakes
•Tsunamis
•Tsunamis
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Coastal Hazards in the
Caribbean (cont’d)
Number of Fatalities
Fatalities in the Insular Caribbean and Belize
by Type
1980-89
2000
1500
Floods
Wind
1000
Other
500
0
1970-1979 1980-1989 1990-1998
Dominican Republic
Haiti
Jamaica
Puerto Rico
Cuba
Windward Islands
Leeward Islands
Belize
Decade Ranges
Bahamas
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Hurricanes:
A Primary Hazard for
Caribbean SIDS
Hurricane Keith
approaching
Belize, 2000
Hurricane Damage:
Occurs primarily from:
– Hurricane waves;
– Storm surge and;
– Beach erosion.
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Hurricane Waves

Waves generated by hurricanes can be very
damaging. Estimates of extreme (i.e.
design) wave heights made throughout the
region are summarized following:
Island
1 in 50 year
wave (m)
1 in 100 year
wave (m)
Jamaica
7.6
8.6
Antigua
13.3
14.9
Grenada
8.1
9.6
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Port Zante, St. Kitts
(Hurricane Lenny, 1999)
Hurricane Waves (cont’d)
Deep water waves change in height as they travel in to
shallower water.
These changes result
from: interactions
between the waves
and the seabed, other
waves and wind
inputs. At the
shoreline, they can be
very damaging,
eroding shorelines.
West coast road, Grenada – Hurricane Lenny, 1999
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Hurricane Waves (cont’d)
Hurricanes waves at the shoreline can also cause
extensive damage to infrastructure, boatyards, etc.
Grenada boatyard, Hurricane Ivan, 2004
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Hurricane Waves (cont’d)
Hurricane waves and storm surge can have tremendous power
Trident Hotel,
Jamaica after
Hurricane Allen,
1980
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Beach Erosion


NE Ambergris Caye, Hurricane
Dean, 2007
The erosion is
exacerbated where
there are buildings (i.e.
vertical walls) in the
wave run-up zone.
Coastal development
must be carefully
designed so as not to
negatively impact
adjacent shoreline
areas.
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Beach Erosion (Cont’d)


During a storm event, the
extreme wave energy
often results in severe
erosion of the beach
and/or shoreline.
This erosion may reach up
to 20-30 m inland,
depending on the storm
severity, and can totally
wipe out beach areas and
adjacent infrastructure.
Grace Bay, TCI – Hurricane
Jeanne (T. Richardson)
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Components of Storm Surge
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Components of Storm Surge (cont’d)
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Characteristics of Storm Surge
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Examples of Storm Surge
High storm waves
Inundation of
waterfront promenade,
Dominica (Lenny, 1999)
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Hazard Mapping – Storm Surge
(Providenciales, TCI)
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Hazard
Mapping –
Storm Surge
Grand
Turk,TCI
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Hurricanes in the Caribbean:
Historical Account
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Records of hurricane damage exist in the archives of
the Caribbean for over five centuries;
Since approximately 1900, hurricane records and
hurricane characteristics have been maintained by
the National Hurricane Center (NHC) and NOAA in
Florida, USA.
These records have improved in accuracy and detail
since the 1950’s, first with the ability of special
reconnaissance aircraft to fly into the eye of these
storms, and later, with the aid of satellite imagery.
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Hurricanes in the Caribbean: Spatial
Distribution
The records over the past century show a
wide band of hurricane activity across the
Caribbean, with the least activity occurring in
the area of Trinidad;
 In general, damage has occurred from storm
surge, waves, wind and rainfall, as all of the
islands have aspects that are vulnerable to
the hazards;
 Latest research indicates possible climate
change impacts (more intense storms).
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Distribution of hurricane activity
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Flooding:
A risk to property and productivity

Over 1300 lives lost to
flooding in Caribbean
over last 20 years
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Flooding in the Caribbean:
Historical Account
In the Lesser Antilles, flooding has been
associated primarily with tropical waves or
hurricanes;
 Flooding may take the form of excessive ponding,
as occurred in Antigua during Hurricane Lenny, or
flash flooding as can occur in the more hilly or
mountainous islands such as Nevis and Dominica;
 In general, all of the islands and their
communities are vulnerable to flooding and
drainage systems need to be designed to take
this into account.

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Earthquakes:
A risk to property and life
The Modified Mercalli Scale
Intensity
Effects
I
Not felt.
II
Felt by persons at rest.
III
Felt indoors. Hanging objects swing.
IV
Vibration like passing of heavy truck. Objects swing.
V
Felt outdoors. Sleepers wakened.
VI
Felt by all. All objects shake. Some breakage.
VII
Difficult to stand. Damage to masonry.
VIII
Difficult to drive. Damage to infrastructure.
IX
Masonry destroyed.
X
Foundations destroyed.
XI
Underground infrastructure out of service.
XII
Total damage.
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Earthquakes and Volcanoes in
the Caribbean
The Caribbean Region, Central and
South America are characterized
by a belt of seismicity. This is
depicted here, with volcanic
epicentres shown as green
triangles and earthquake
epicenters shown as orange dots.
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Some earthquakes in the Caribbean

Major Earthquakes
– Port Royal, Jamaica (1692)
– Trinidad (1766)
– Antigua (1843)

Minor Events
– St. Lucia (1953)
– Trinidad (1954)
– Antigua (1974)
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Plate Tectonic Setting
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Volcanoes:
A risk to property and life
A significant Hazard in
the Lesser Antilles
•Soufriere, St. Vincent (1718,
1812, 1902-3, 1979)
•Mt. Pelee, Martinique (1902,
1929-32)
•Soufriere Hills, Montserrat
(1997)
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Soufriere Hills, Montserrat
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Before
After
Plymouth, Montserrat
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Volcanoes in the Caribbean:
Historical Account
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17 Volcanoes have erupted in the Eastern Caribbean.
25 Volcanic Centres with the potential to erupt.
Approx. 40,000 lives lost in 1902 eruptions (St.
Vincent and Martinique).
Warning time has ranged from 14 days to 14 years.
The famous Port Royal disaster of 1692 was initially
caused by an earthquake which liquefied an alluvial
plane causing it to slide into the sea, the resulting
tsunami was several metres in height and caused
over 2000 deaths.
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Tsunamis:
are we at risk?
More a problem in the
Lesser Antilles
 Caused by ocean centred
earthquakes, or volcanic
eruptions.
 Greatest risk presently
posed by “Kick ‘em
Jenny”

SeaBeam image of Kick 'em Jenny
constructed from measurements taken
from the NOAA Research Vessel Ronald H.
Brown on March 12 2002.
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Tsunamis in the Caribbean:
Historical Account
Summary Table of Tsunami Activity
Date
1897-Nov-29
1907-Jan-14
1918-Oct-11
1946-Aug
Location
West Indies
Jamaica
Puerto Rico
Dominican
Republic
1953-May-31 Dominican
Republic
1955-Jan-18 Venezuela
Comment
Large tsunami at Montserrat
Tsunami generated, main damage at Kingston
Tsunami caused fatalities and damage at Point
Borinquen and Aguadilla; also damage at
Mayaguez
Town of Matanzas badly damaged and
abandoned; more than 100 persons killed; minor
damage on coast of Haiti
Very slight tsunami; amplitude 0.2 ft at Puerto
Plata
Tsunami caused damage at La Vela, Venezuela
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Tsunami Risk Zones
•Tsunami triggered by seismic activity; submarine landslides.
•Resulting waves could be of the order of 4m (Cat 1-2)
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