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MANAGING NATURAL
DISASTERS IN THE COASTAL
AREAS
BY
JOSEPH R MUKABANA, PhD
Kenya Meteorological Services
P.O. Box 30259, Nairobi,
KENYA
Tel: 254-2-567880
Fax: 254-2-576955
E-mail: mukabana@meteo.go.ke
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INTRODUCTION:
Economic activities in coastal ocean
environment account for substantial
proportions of the gross domestic products of
many maritime countries.
This is due to growing reliance on:
– Coastal and Marine living resources;
– Coastal and Marine non-living resources;
– Shipping and Trade and;
– Coastal Tourism.
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INTRODUCTION Cont…
To effectively improve and sustain development and to
mitigate or reverse the undesirable trends or effects of
the natural disasters in coastal areas, we need to:
Define disasters;
Critically examine natural disasters associated with coastal
areas; and
Analyze the causes of these disasters and associated impacts.
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Natural Disasters
Definition and General Consideration :
A Disaster is a serious disruption of the functioning of a
society, causing widespread human, property or
environmental losses which exceed the ability of the
affected society to cope using only its own resources.
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Natural Disasters (Cont….)
Plants and animals including humans are enacted within
the global theatre of natural disasters arising from a
variety of natural processes e.g.
Volcanic eruptions;
Earthquakes;
Tropical cyclones;
Floods;
Droughts;
Land/Mud slides;
Outer space meteorite
Tsunamis etc.
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Natural Disasters (cont…)
More recent examples of the potential hazards of the extreme events have
been demonstrated by:
The impacts of the India Ocean tsunami triggered by under-sea earthquake
in Band Aceh (Indonesia) on 26th December 2004 and which killed over
160,000 and destroyed property worth billions of US dollars;
The 1997/98 El-Niño related floods in some parts of eastern Africa; and
Floods in Mozambique.
The El-Nino floods of 1997/98 in East Africa were immediately followed by
one of the longest and severest droughts in the history of the sub-region
associated with the 1999-2000 La Nina episode. The drought impacts are
still persistent in some areas to date.
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Types of Natural Disasters in
Coastal Areas Related to Climate
Natural disasters in coastal areas can be categorised into three
major types i.e. geological, biological and meteorological.
1) Geological
• Those driven by earth’s internal energy, e.g. earthquakes and
volcanoes.
•
Those resulting from land surface processes or land use/cover changes
(agriculture, mining, settlement, etc).
Both these two processes can cause landslides, snow avalanches, river
flooding, soil erosion, mudslides (collapsing soils) water and soil
pollution, coastal flooding, ocean processes like storm surges, tsunamis,
etc.
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Types of Natural Disasters
continued
2) Biological
:
These are in the form of disease epidemics and epizootics like malaria,
proliferation of pests and parasites and invasion of areas by insects.
3) Meteorological
:
These result from extreme climate events e.g. floods, lightning strikes and
resulting fires, droughts, thunderstorms, tropical cyclones, tornados,
waterspouts, hailstorms, sandstorms, frost, etc
At times the disasters are as a result of a combination of two or all three of
these processes.
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Impacts of Natural Disasters on
Coastal Populations and Their
Management
The effect of a disaster on populations may either be
direct or indirect.
Direct Impacts
• Direct impacts of a disaster involves injury, death to
human beings, plants and animals, and damage to
property.
Indirect Impacts
• Indirect impacts are through a knock-on effect (“aftershocks”) from reduced economic resources caused
by the disaster and disrupted ecosystems.
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Impacts of Natural Disasters (Cont...)
Tropical Cyclones and Storm Surges
• Over the centuries, the deadliest and the
most destructive element of a tropical
cyclone, has been the storm surge.
• Thousands of people living in low-lying
coastal areas have lost lives and property
through storm surges.
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A Storm Surge is an
abnormal rise of sea
level caused by a
cyclone moving over a
continental shelf
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Flooding of LowLying Coastal Areas
Effect of local Tides
Erosion of Beaches
Effect of local
Coastal
Configuration
Damage to onshore
& offshore
installations
Damage to Shipping
& Fishing Facilities
Low Atmospheric
Pressure in the Centre
Storm Surge
Loss of
Human
Life:
Injuries
Wind
Urban
Bushfire
Damage to
structures &
Continent
Loss of Soil
Fertility
from Saline
Intrusion
Land
Subsidence
Contaminati
on of
Domestic
Water
Supply
Destruction
of
Vegetation,
Crops,
Livestock
Loss of
Communications
& Power
Rain
Flooding
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Potential Impact upon Landfall of a Tropical Cyclone
Table 1: DEATHS DUE STORM
SURGES
YEARS
COUNTRY
DEATHS
1822 - 1991
Bangladesh
930,000
1737 - 1999
India
740,000
1923 - 1960
Japan
255,000
1900
USA
6,000
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Impacts of Natural Disasters (cont..)
Tsunamis
A series of traveling ocean waves of extremely long
length generated primarily by earthquakes, volcanic
eruptions, outer-space meteorite splash or landslides
occurring below or near the ocean floor.
Tsunamis are a threat to life and property for all
coastal residents living near the ocean.
Although 80% of the tsunamis occur in the
Pacific, they can also threaten coastlines of
countries in other regions, including the Indian
Ocean, Mediterranean Sea, Caribbean region, and
even the Atlantic Ocean.
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Impacts of Natural Disasters (cont..)
The Indian Ocean Tsunami
Slummed in more that 8 countries in the Indian Ocean realm and
killed more than 160,000 people;
According to Asian Development Bank (ADB) Report, the number of
the poor in India could rise by 645,000 and by 250,000 in Sri Lanka.
In the Maldives, where about half the island nation's houses were
affected, more than 50 per cent of the population could fall into
poverty, ADB said.
FAO, a UN agency, report reckons that Indian Ocean fisheries have
been devastated by the tsunami, endangering the livelihoods of
hundreds of thousands of families.
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ENHANCEMENT OF A TSUNAMI WAVE
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RESPONSE TO A TSUNAMI WAVE
1, 1946 People flee as a tsunami attacks downtown Hilo, Hawaii (Bishop
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Museum Archives)
Impacts of Natural Disasters (cont..)
Floods
Floods are mainly triggered by severe
thunderstorms, cyclones, the El-Nino related
phenomenon or monsoons.
In low-lying coastal areas, storm surges, tsunamis or
rivers swollen by exceptionally high tides can cause
flooding.
Floods can threaten human life and property.
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Floods
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Impacts of Natural Disasters (cont..)
Landslides
Land slides occur when heavy rains send large amounts
of earth, rock, sand or mud flowing swiftly down mountain
slopes.
Land slides are intensified where vegetation is scarce due
to bush fires, overgrazing, deforestation, impacts of
droughts etc.
Two weeks of continuous rainfall towards the end of 1999
saturated soils in Venezuela to the extent that thousands
of landslides shot down Avila mountain in the state of
Vargas, washing away towns, killing an estimated 15,000
people and costing almost US$ 2 billion.
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Landslides
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Impacts of Natural Disasters(cont..)
Droughts
Droughts are a result of a natural reduction in precipitation over a long time;
When rainfall becomes relatively scant or infrequent, it can disrupt the
normal balance between precipitation and the evaporation-transpiration
process, and drought can begin;
Crops and livestock can die due to drought;
Hydro-electric power dams dry-up disrupting industrial activities;
Lack of adequate water for drinking and sanitation leads to malnutrition thirst
and disease outbreaks among humans and animals; and
The human, economic losses and costs due to environmental degradation
mounts up rapidly.
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Impact of droughts on Agriculture
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Impacts of Natural Disasters (cont..)
Disease Outbreaks and Health Related
Disasters:
Disease outbreaks impact negatively on the
health of a community;
In tropical counties, flood water can become a
breeding ground for mosquitoes, tsetse fly
creating an increased risk of malaria, sleeping
sickness, typhoid, cholera and dengue fever
outbreak;
Droughts lead to thirst, malnutrition and
famine due to lack of water and food scarcity.
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Climate and Natural Disasters
Statistics show that over 70% of all natural disasters
experienced in coastal areas all over the world are related to
extreme climate events. Occurrence of one or more of
climate related disasters may trigger other disasters (e.g.
drought, floods )
An increasing body of observations gives a collective picture
of a warming world and other changes in the climate
system.
Cause: rise in concentration of the main anthropogenic
greenhouse gases in the lower atmosphere (carbon dioxide,
methane and oxides of nitrogen) which affect the earth’s
radiation budget and lead to warming of the earth’s surface.
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Climate and Natural Disasters (cont...)
Global surface temperature has increased by between 0.4°C and 0.8°C
since 1860 with the 1990s being the warmest decade;
Tide gauge data show that a rise in sea level during the 20th century is
between 10cm and 20cm.
Model simulations indicate that a doubling of carbon dioxide by the year
2100 will result in a mean global warming of 1.1 to 3.1 °C and a sea level rise
of 11 to 77cm.
Global warming will cause mass expansion of sea water, melting of glaciers
and rise in sea level.
Scientific evidence already points towards a discernible climate change.
This is likely to alter the frequency and magnitude of natural disasters
associated with extreme climate events along the coastal areas.
.
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Integrated Management of Natural
Disasters Along Coastal Areas
The best way to confront natural disasters is to:
 Create a culture of safety among the communities at risk;
 Enhance the capacity of the people living in vulnerable areas.
Preparedness is key in helping communities manage the inevitable
disasters when they do occur.
This can only be achieved by having cross-sectoral approach in putting
up early warning systems.
As shown above, any sustainable management of disasters in the coastal
areas will require the integration of climate information in all aspects of
planning.
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Natural Disaster Preparedness and Adaptation
for Coastal Areas
This should cover:
1.
Establishment of early warning systems and capacity
building of the national institutions responsible for
data collection, analysis and issuance of forecasts
and warnings of the disasters.
The warnings need to be:
 Very Accurate to invite confidence to the
targeted community;
 Timely to allow a high degree of
preparedness; and
 Mechanisms need to be in place to facilitate
immediate and effective response.
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Tsunami Early Warning System
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Natural Disaster Preparedness and Adaptation
for Coastal Areas (cont...)
2. Risk assessments and zoning of the land-use
practices in the coastal areas and proper planning of
development at the coastal zone.
3. Introduction of Government policies to protect
vulnerable communities.
4. Evacuation plans to be followed in the event of a
disaster happening or receiving a warning of an
impending disaster.
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Natural Disaster Preparedness and Adaptation
for Coastal Areas (cont...)
In the case of Tsunamis, Cyclones, Storm
Surges and Floods these initiatives
should include:
Protection of life and property including
buildings through construction of
seawalls, barrages, dykes, coastal
embankments and dams.
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Natural Disaster Preparedness and Adaptation for
Coastal Areas (cont...)
In the case of Landslides
Initiatives should be directed towards;
•
•
•
•
•
•
Construction of hydraulic structures to control the
flows;
Construction of channels or deflection walls to
direct flow around buildings;
Planting of ground cover on slopes; and
Building retaining walls in mudflow areas
Construction of sediment control dams; and
Afforestation.
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Natural Disaster Preparedness and Adaptation for
Coastal Areas (cont...)
In the case of Droughts Preparedness and adaptation, initiatives should
be directed towards developing drought-resilience policies designed to
head off adverse impacts. These include policies on:
 The boosting of water supplies in vulnerable coastal areas;
 Introduction of water conservation programmes;
 Irrigation as a tool to reduce adverse impacts of droughts;
 Water recycling in cities;
 Encouragement of the use of statistical techniques of data,
particularly rainfall, to find systematic patterns like trends,
persistence or cycles.
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Natural Disaster Preparedness and Adaptation
for Coastal Areas (cont...)
In the case of Disease Outbreaks and Health
Related Disasters
Initiatives should include formation of permanent
Search and Rescue teams to carry out relief and
rehabilitation initiatives. The team should have the
capacity to provide services like medical care,
clean water, balanced food, etc.
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Natural Disaster Preparedness and Adaptation for
Coastal Areas (cont...)
Disaster Managers need to put in place elaborate evacuation
plans to be followed in the event of a disaster happening or
receiving a warning of an impending disaster. Specifically:

A secure and reliable communication system need to be in place for
rapid response;

An elaborate evacuation procedure and transport arrangement;

Emergency pathways (routes) to safe areas (shelters and high
grounds) properly highlighted.
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Mitigation Strategies
Disaster preparedness will have to include the
following:
• Evacuation measures;
• Provision of medical aid;
• Prompt disposal of dead bodies and animal
carcasses;
• Preventive means against epidemics;
• Supply of food and safe drinking water.
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Conclusion and Way Forward
• In order to mitigate the effects of natural disasters in
coastal areas, it is necessary to understand the
dynamics of the processes involved and give
accurate and timely early warnings;
• Over 70% of natural disasters in coastal areas are
climate related.Hence, management of these
disasters will need the integration of weather and
climate Monitoring in the process.
• Capacity building in areas of observing the ocean
and the atmosphere for accurate and timely
forecasts of extreme climate events is necessary.
• Cross-sectoral
multi-hazard
approach
and
coordination between various agencies is necessary
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in the effective management of coastal disasters.
Thank You For Your Kind
Attention
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