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Climate change and Urban
Vulnerability in Africa
Assessing vulnerability of urban systems,
population and goods in relation to natural and
man-made disasters in Africa
“Training on the job” Course on Hazards, Risk and
(Bayesian) multi-risk assessement
Napoli, 24.10.2011 – 11.11.2011
24/05/2017
Fatemeh Jalayer
1
Risk assessment:
The engineering point of view
R = H• V • E
R : risk
H : hazard
V : vulnerability
E : exposure
24/05/2017
Fatemeh Jalayer
Slide 2
What is hazard?
A dangerous phenomenon, substance, human activity or condition that may cause
loss of life, injury or other health impacts, property damage, loss of livelihoods and
services, social and economic disruption, or environmental damage.
24/05/2017
Fatemeh Jalayer
Slide 3
Risk assessment:
The engineering point of view
R = H• V • E
R : risk
H : hazard
V : vulnerability
E : exposure
24/05/2017
Fatemeh Jalayer
Slide 4
What is the vulnerability?
“... a human condition or process resulting from physical, social,
economic, and environmental factors which determine the likelihood
and scale of damage from the impact of a given hazard“ (United
Nations Development Programme, 2004)
The fraction of the total value at risk that could be lost after a specific
adverse event (Principles of multi-risk assessment, EU, EUR 23615,
2009).
“... Vulnerability is the characteristics and circumstances of a community,
system or asset that make it susceptible to the damaging effects of a
hazard (2009 UN International Strategy for Risk Reduction)
24/05/2017
Fatemeh Jalayer
Slide 5
What is the climate change
vulnerability?
“... Vulnerability is the degree to which a system is susceptible to, or unable to
cope with, adverse effects of climate change, including climate variability and
extremes (United States Environmental Protection glossary for climate
change).
“... Vulnerability is a function of the character, magnitude, and rate of climate
change and variation to which a system is exposed, its sensitivity, and its
adaptive capacity (United States Environmental Protection glossary for climate
change).
24/05/2017
Fatemeh Jalayer
Slide 6
Some general aspects of the
vulnerability
The concept of Vulnerability seems always to involve a
“system”.
The “system” is a set of interacting or interdependent
components forming an integrated whole.
boundary
surroundings
24/05/2017
system
Fatemeh Jalayer
Slide 7
Some general aspects of the
vulnerability
The definition of a system is very broad; it can stand
for the environment, the community, the assets, the
buildings, the roads and so on.
24/05/2017
Fatemeh Jalayer
Slide 8
And hence,
different types of vulnerability
Technical (Physical)
Vulnerability of urban structures and life-lines
Environmental
Vulnerability of agriculture
Environmental fragility (e.g., groundwaters, land)
Social
The specific social inequality of people in the context of a disaster
… in broad terms, how susceptible people are to a hazard
Economic
Vulnerability of different economic sectors
Institutional
Effectiveness and failure of organized structures and institutions
24/05/2017
Fatemeh Jalayer
Slide 9
Some general aspects of the
vulnerability
A system is consisted of many components. It is not
trivial to take into account the interaction of the
components.
24/05/2017
Fatemeh Jalayer
Slide 10
Some general aspects of the
vulnerability
Vulnerability is subjected to variability:
Temporal:
• The hazard on the system can change with time
• The system can change in time.
Spatial:
• The system is usually distributed spatially.
24/05/2017
Fatemeh Jalayer
Slide 11
Some general aspects of the
vulnerability
Vulnerability assessment is usually characterized by
incomplete information and its assessment is a
probability-based procedure.
•
•
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Incomplete information regarding the hazard
evaluation
Incomplete information regarding the system
parameters
Fatemeh Jalayer
Slide 12
Some general aspects of the
vulnerability
The concepts of hazard, vulnerability and risk have quite a
dynamic nature. What is called vulnerability from a point of
view, would be called risk by some and hazard by some other
at the same time and nobody is wrong!
R = H• V • E
24/05/2017
Fatemeh Jalayer
Slide 13
Capacity
Before to start we need the definition of capacity:
The combination of all the strengths, attributes and resources
available within a community, society or organization that can
be used to achieve agreed goals.
Capacity may include infrastructure and physical means,
institutions, societal coping abilities, as well as human
knowledge, skills and collective attributes such as social
relationships, leadership and management.
24/05/2017
Fatemeh Jalayer
Slide 14
A quantitative definition for
vulnerability rooted in engineering
The vulnerability of a system or its components can be defined
as the probability of its failure:
• C is the system capacity
• D is the demand a system can be subjected to
• C and D are attributes of the same property or
quantity (they have the same units)
24/05/2017
Fatemeh Jalayer
Slide 15
What is the system demand and
how it’s related to hazard
Demand: An urgent requirement or need
Demand can be interpreted as the requirements imposed
to the system by the hazard.
24/05/2017
Fatemeh Jalayer
Slide 16
Linking hazard and vulnerability
In order to link vulnerability to hazard in an efficient way it is
useful to introduce a variable that links hazard to system
demand.
In the earthquake engineering jargon, this variable is called an
intensity measure (IM).
It can be thought of as an interface variable representing the
intensity of hazard .
24/05/2017
Fatemeh Jalayer
Slide 17
Vulnerability and Hazard
Vulnerability can be calculated by expanding for all possible
intensities of hazard:
• p(IM) represents hazard
• P(D>C|IM) is called the system fragility
24/05/2017
Fatemeh Jalayer
Slide 18
System vulnerability
vs
Component vulnerability
The system vulnerability is a function of the vulnerability of
its components. There are different ways to calculate the
system vulnerability:
Employing a generalized definition of demand and capacity
(the cut-set theory) for the system.
Calculating the vulnerability of the system as a function of
components’ vulnerability.
Using simulation methods and calculating directly the system
vulnerability.
24/05/2017
Fatemeh Jalayer
Slide 19