Download Hazards induced by climate change

Climate change induced natural hazards in the Caribbean
Mr. Rafi Ahmad
The University of the West Indies, Mona
The Caribbean Community Climate Change Centre
CONFERENCE
CLIMATE CHANGE IMPACTS ON THE CARIBBEAN
15-17 June 2007
NATURAL HAZARDS IN THE CARIBBEAN AND
CLIMATE CHANGE
RAFI AHMAD
[email protected]
Affiliations:
Unit for Disaster Studies
http://www.mona.uwi.edu.jm/uds/
Department of Geography and Geology
MONA GEOINFORMATICS INSTITUTE
http://www.monainformatixltd.com
The University of the West Indies at Mona
This presentation focuses on
• the physical Caribbean
• the active processes which have shaped
the Caribbean lands
• hazards and disasters
• climate change and natural hazards
Message
CLIMATE CHANGE DOES NOT
CAUSE DISASTERS,
BUT EXACERBATE HAZARDS
THE CARIBBEAN AND ITS INHERENT ACTIVE
PROCESSES or HAZARDS
WE PICK ONE OF THE ISLANDS TO
APPRECIATE INTRA-ISLAND WORKINGS
VITAL STATISTICS OF JAMAICA
• LAND AREA:
1083, 000Ha
• HIGHLANDS
RELIEF: 300 TO > 2,000m,
WITH SLOPES >200m : 870,000Ha
(ABOUT 80%)
• MAXIMUM LENGTH/WIDTH:
235 Km/35 TO 82 Km
• COASTLINE:
1,022Km
TOTAL LENGTH OF MAJOR RIVERS AND
STREAMS (blue line method):
4, 560 km
DRAINAGE DENSITY:
2.375km of WATERCOURSE/km2
LONGEST COURSE:
27Km
POPULATION DENSITY:
• 2,293/1000 Ha
POPULATION WITHIN 5KM OF COAST:
• 1.3 MILLION PERSONS
Population within 1km of coast:
• 500,000 persons
ROADS: New highways not included
Total Length = 18,197 km
Density: 1.7 km/km2
Roads within 1km of coast: 714km
Railway: Total length = 293 km
WATER RESOURCES
• Highly fractured bedrock creates porosity and
permeability for rainfall to infiltrate bedrock.
• Historical data suggest that the availability
and distribution of water is subject to severe
to moderate impact of natural hazard
processes.
RAINFALL: Hurricanes, tropical storms and cold
fronts
Limestone Plateau with Hills
•
Average annual rainfall between 125 and 375 cm.
•
•
Limestone aquifers provide 96% of the groundwater: 3,294 Mm3 yr-1.; Springs common
Hillslopes are decorated with historic and new landslide scarps. Landslide deposits have
created debris fans at the base of hill slopes.
Uplands-Mountainous Terrain
• Average annual rainfall between 190 and 700 cm; orographic rainfall
•
•
pattern
Hillslopes are decorated with historic and new landslide scarps. Landslide
deposits have created debris fans at the base of hill slopes.
Act as basement aquicludes (water-excluding rocks that have little or no porosity
or permeability): provide 666 Mm3 yr-1 of water as surface run-off. Springs
common.
Coastal Plains and Marshlands
•
Alluvium aquifers provide 4% of the groundwater: 124 Mm3 yr-1. Springs.
• Average annual rainfall about 190 cm.
All of the major population/tourist centres of Jamaica are
coastal settlements located on debris and alluvial fans
on the mouths of water courses
Alluvial Fan Flooding Hazard and Coastal Flooding Hazard Map of the Bull Bay Area, Jamaica
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See Gu id l in es o n th e u se of th e M ap
Prepared by: Theres a R odriguez, Noel M cKenzie, Rafi A hmad
Date: M arch 3, 2006
NATURAL HAZARDS
• 1. HURRICANES
Jamaica lies within the track of Atlantic
hurricane belt and tropical storms and cold
fronts.
Hazards include:
• Wind damage,
• Rainfall induced landslides,
• Riverine sediment floods and water floods.
• Entire coastline of Jamaica is exposed to
coastal flooding related to storm surge and
tsunami hazard.
2.LANDSLIDE SUSCEPTIBILITY
Landslide triggers are earthquakes (> M 4.0) and/
or precipitation (200-300mm/24 hr).
• Submarine landslides following the earthquakes
in1692 and 1907 caused localized tsunamis)
• Limestone Plateau with Hills Moderate to high
• Uplands-Mountainous Terrain Very high
• Coastal Plains and Marshlands Low
• land-water interface is subject to submarine
landslides/mass movements, for example,
destruction of Port Royal by an earthquake in
1692; breakage of submarine communication
cables following the earthquakes in 1907 (M6.5)
and 1993 (M5,4) .
3.FLOODING POTENTIAL All the major population
and tourist centres of Jamaica are coastal settlements
located on debris and alluvial fans on the mouths of
water courses.
A)
•
•
•
RIVERINE FLOODING
Limestone Plateau with Hills
Moderate to high; Alluvial fan flooding.
Flooding processes in the small and steep watersheds of Jamaica range from
debris flows-mudflows-debris floods and mud floods-water floods.
• Debris floods and Mud floods occur after every significant rainfall (200300mm/24 hr).
Uplands-Mountainous Terrain
• Very high, Alluvial fan flooding.
• Flooding processes in the small and steep watersheds of Jamaica range from
debris flows-mudflows-debris floods and mud floods-water floods.
• Debris floods and Mud floods occur after every significant rainfall (200300mm/24 hr).
Coastal Plains and Marshlands
• Very high; subject to both coastal and riverine flooding. Alluvial fan flooding
(B)COASTAL FLOODING
• Entire coastline of Jamaica is exposed to Tsunami and storm surge hazard.
FLOOD PRONE COMMUNITIES IN JAMAICA ARE
LOCATED ON ALLUVIAL FANS AT THE MOUTHS OF
RIVERS. EXAMPLES: Harbour View, Kingston, Ocho Rios,
Yallahs fan.
FLOODING IN JAMAICA IS GENERALLY A CASE OF
ALLUVIAL FAN FLOODING.
Map source: Water Resources Authority,
Jamaica.
EARLY WARNING
RAINFALL INTENSITY-DURATION THRESHOLD FOR SHALLOW
LANDSLIDES IN EASTERN JAMAICA:
Using data for 19 storms, 1951-2002, a threshold relation between rainfall
intensity-duration and landsliding was established
Threshold for rainfall-induced shallow landslides
in Eastern Jamaica (1951-2002)
Rainfall Intensity (mm/hour)
100
10
1
1
10
100
Rainfall Duration (hours)
Rainfall events producing landslides (2001-2002)
Storms that did not cause landslides (1993-1999)
Rainfalls that caused landslides (1951-1988)
1000
4.SEISMIC HAZARD
ground shaking; landslides; liquefaction; tsunami
Limestone Plateau with Hills
• Moderate to high, depending on
location.
Uplands-Mountainous Terrain
• Moderate to high, depending on
location.
Coastal Plains and Marshlands
• High; some areas subject to
liquefaction. Tsunami hazard
5. LAND DEGRADATION IS PRIMARILY
CONTROLLED BY LANDSLIDE-RELATED
EROSION RATES IN HILLY TERRAIN
Limestone Plateau with Hills
• Moderate to high.
• Approximate area affected: 685,000 ha
Uplands-Mountainous Terrain
• Very high.
• Approximate area affected: 250,000 ha
• Coastal Plains and Marshlands
• Low to moderate.
• Approximate area affected: 120,000 ha
Natural Hazards Profile of
Jamaica:
EARTHQUAKES:
Zone 3 : MMI VIII Probable maximum intensity
(Modified Mercalli Intensity Scale) with an exceedance
probability of 10% in 50 years (equivalent to a “return
period” of 475 years) for medium sub-soil conditions.
Kingston: Large city with “Mexico City effect”
TSUNAMI AND STORM SURGES:
ENTIRE COASTLINE IS EXPOSED TO TSUNAMI AND
STORM SURGE HAZARD
TROPICAL STORMS TRACKS:
• Probable maximum intensity (SS: Saffir-Simpson
hurricane scale) with an exceedance probability of 10%
in 10 years (equivalent to a “return period” of 100
years)
• Zone 4: SS 4 (210-249 km/hr)
POTENTIALLY HAZARDOUS NATURAL
PHENOMENA AND PROCESSES IN THE
CARIBBEAN
MULTIPLE HAZARD SCENARIO
Large-scale wildfires are not reported in the small island states.
ATMOSPHERIC
• Hurricanes Tropical storms Tornadoes
• Rainfall
• Lightning
• Hailstorms
• Bolides
• Temperature changes
SEISMIC
•
•
•
•
•
•
•
Fault ruptures
Ground shaking
Liquefaction
Land Uplift and Subsidence
Landslides
Tsunami
Seiches
CARIBBEAN PLATE
VOLCANIC
•
•
•
•
•
•
Lava flows
Mudflows
Pyroclastic flows
Projectiles and lateral blasts
Tephra (ash, cinders, lapilli)
Gases
GEOLOGIC/HYDROLOGIC
• Landslides
• Debris Flows
• Mud Flows
• Submarine slides
• Subsidence
• Mud Volcanism
HYDROLOGIC
•
•
•
•
•
•
River flooding
Erosion and sedimentation
Desertification
Salinization
Drought
Coastal flooding
(Storm surge, Tsunami)
• Sea-level rise
The Caribbean region’s
environmental problems include:
Hazards induced by climate change:
• landslides,
• flooding (coastal flooding and river
flooding),
• hurricanes ( winds exceeding 118km/hr,
heavy rainfall, storm surge)
• desertification, erosion and
sedimentation, salinization
• degradation of coral reefs
•
•
•
•
•
River-basin degradation
Deforestation
Waste disposal
Loss of habitat and biodiversity
Pollution of freshwater, coastlands
and the atmosphere
From: CDB and CARICOM, 2004;
Benn, 2004 in ECLAC, 2005
Hydro-meteorological disasters in Latin America
and the Caribbean, 1990-2004; ECLAC,2005
www.eclac.cl/publicaciones/xml/0/21540/lcg2331.pdf
CLIMATE CHANGE AND HAZARDS
The Intergovernmental Panel on Climate Change has
published The Physical Science Basis of projections
and likely scenarios on climate change on 2
February 2007, AR4
http://ipcc-wg1.ucar.edu/wg1/wg1-report.html
How would climate change
possibly manifest itself on active
natural processes affecting the
small island states of the
Caribbean is not definite
The sizes of the individual islands are
not large enough to have significant
shifts in the intra-island rainfall
distribution patterns
Large-scale rate changes would be
expected in view of anomalous sea
surface temperatures and
changes in wind shear patterns.
However, there are a couple
of likely scenarios that may
be speculated.
• Any significant (whatever that is)
sea level rise will affect the littoral
drift along the coast with some
changes to the location and
seasonal change to beaches due to
increased or decreased sediment
nourishment
There also would be a change in the
coastal areas subject to storm surge
during hurricanes or other major tropical
storms; probably a greater run-up is
likely.
• There may also be an increase in the
sea cliff retreat where wave action
becomes more effective due to sea
level rise or higher energy associated
with hurricanes and tropical storms.
Rising sea level would affect the base
level of major streams, in that incision
of river valleys might slow and some
slope processes might change as a
result.
This is likely to be a complex
interaction especially if the number
and/or power of hurricanes and
tropical storms increase.
The greater delivery of sediment to the
valleys from rainfall-induced landslides
may result in greater aggradation in
these valleys where down cutting is
less.
Flooding events and areas affected by
flooding in the future may very well
change due to the base level changes,
greater rainfall and increased sediment
deposition.
Summary
CHALLENGES FOR DISASTER
REDUCTION
From:
Report of the Subcommittee on
disaster reduction,
2005
1. Provide Hazard and Disaster Information
Where and When it is Needed.
Improve data collection to increase
understanding of the ways in which
hazards evolve.
Create standards for sharing, storing, and
analyzing data.
2. Understand the Natural Processes That
Produce Hazards.
Improve models and visualization
techniques.
3. Develop Hazard Mitigation
Strategies and Technologies.
Create resilient structures and
infrastructure systems using
advanced building technologies.
Support structural advances with
effective nonstructural mitigation.
Quantify the monetary benefits of
disaster mitigation using economic
modeling.
4. Recognize and Reduce
Vulnerability of Interdependent
Critical Infrastructure.
Develop science and technology to
prevent cascading failures in
public infrastructure systems.
Enhance the ability to protect public
health before and after a hazard
event.
5. Assess Disaster Resilience Using
Standard Methods.
• Support intelligent community
planning and investment strategies
and protect natural resources with
comprehensive risk assessments.
• Assess the resilience of the natural
and human environment.
• Learn from each hazard event.
6. Promote Risk-Wise Behavior.
• Raise public awareness of local
hazards.
• Warn people with consistent,
accessible, and actionable messages
and a national all-hazards emergency
communication system.
• Develop policies that promote riskwise behavior and are based in
social science research.