Transcript Document
Establishing Basic Parameters:
Risk Assessment
Session 2
World Bank Institute
Risk Sensitive Land Use Planning
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Risk Assessment:
Concepts and Definitions
Risk
Probability/likelihood of loss due to one or more hazard events
in pre-defined geographical area
Depends on severity of hazard, vulnerability of exposed assets
and the capacity to cope with risk
Includes time dimension or frequency of occurrence of hazards
Risk Assessment
Analysis of both the severity of hazard and vulnerability of assets
in a particular location
Could include a time-dependent dimension
Can be undertaken at various levels of precision
Provides input to planning strategies
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Risk Assessment: The Process
Process to determine severity and spatial distribution of risk
Analytical tool for disaster risk reduction
Basis for land use planning interventions
Hazard
Assessment
Capacity
Assessment
Assets at
Risk
Vulnerability
Assessment
Risk
Assessment
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Risk Assessment: Initial Decisions
Precision of data
Time-related factors
Relatively rough information sufficient for public information and
commitment building
Greater levels of precision required to justify differential treatment of land
Increasing precision increases the cost of assessment
Recurrence interval of extreme events
Current land use practices or future risks associated with alternative land
use scenarios
Depth of assessment
Hazard analysis defines the spatial scale of the hazard and also generates
commitment to public policy initiatives
Vulnerability analysis helps to understand the consequences of alternative
land use configurations
Probabilistic risk analysis captures the full range of potential casualty and
damage experiences for a rational comprehensive approach
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Step 1: Hazard Identification and Analysis
Analysis of:
Quantifies severity of hazard at a given site
Hazards that may occur in a given area
The history of the hazard occurrence
The hazard intensity and impact
Change in exposure with respect to time
Areas that would be most affected
within the city
Population groups impacted the most
As a point estimate, or
As a time-dependent probabilistic statement
Results can be mapped to increase understanding and usage
Geographic Information Systems can be useful
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Step 2: Vulnerability Analysis
Quantifies the degree of susceptibility of people and assets
to sustain damage under various levels of hazard
Physical vulnerability varies across a city and depends on the existing
building stock and site conditions
Socio-economic vulnerability depends on population distribution,
socio-economic status, gender, race/ethnicity, age, nature of economy etc.
Indicates elements at risk that need land use planning
interventions
Integrates capacity analysis to estimate protective and coping
capabilities
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Step 3: Risk Analysis
Combines parameters of hazard and vulnerability to
quantify losses
Time dependent risk assessment provides basis to
determine acceptable level of risk
Losses may include casualty, direct material losses and indirect
material losses
May or may not be time-dependent
Can be used to determine benefit-cost for land use planning interventions
Level of precision/approximation of risk assessment
depends on purpose of its use
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Risk Assessment:
Methods & Approaches
Risk Assessment
Quantitative
Use analytical
tools
Provides
technical and
financial
parameters for
land use planning
Qualitative
Suitable for
subjective data
that is difficult to
quantify
Do not require high
level of technical
expertise
Can be performed
by various
stakeholders
Expert-driven
Performed by
experts
Requires high
level of technical
expertise
Relies on
quantitative
methods
Risk Sensitive Land Use Planning
Community-driven
Participatory in nature
Incorporate variations in
perception and
acceptability of risk of
stakeholders
Community-based hazard
and risk mapping
Vulnerability and capacity
assessments
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Risk Assessment Techniques:
Risk Identification
Determines hazards that may occur in area
Identifies and characterizes susceptible elements
to the hazard
Includes description of area and its environment
Includes vulnerability and capacity of population,
institutions and critical facilities
Uses mapping tools to facilitate the process of
stakeholders’ consultation and provide input to land
use planning
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Risk Assessment Techniques:
Risk Checklist
Best for a specific project,
event or area
Best for parameters that are
difficult to quantify
Helps planners follow
systematic procedure for
land use decisions
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Risk Assessment Techniques:
Risk Matrix
Charts parameters of frequency versus severity of
hazards
Can be both quantitative
and qualitative
Uses two-dimensional chart
Interpretation must be
consistent
Used by planners to
prioritize types of risks
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Risk Assessment Techniques:
Risk Matrix
Risk Index to Community
Ranking of multiple locations on basis of a risk
index (Location 2 has highest risk)
Location
1
Location
2
Location
3
Location
4
Severity of Hazard
3
5
4
2
Frequency of Hazard
5
3
3
1
Human Loss Potential
3
5
4
3
Economic Loss Potential
3
5
4
4
Response Capacity
3
3
3
3
Cumulative
17
21
18
13
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Risk Assessment Techniques:
Risk Matrix
Ranking of multiple hazards
Forest Fires
Very High
Floods
High
Medium
Droughts
Epidemics
Technological
FREQUENCY
Low
Earthquakes
Very Low
Very Low
Low
Medium
SEVERITY (LOSS)
High
Very High
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Risk Sensitive Land Use Planning
Risk Assessment Methods:
Scenario Analysis
Calculates potential losses from a hypothetical event
Provides understanding of the spatial distribution of losses
to the built environment
Develops internal institutional knowledge regarding vulnerabilities
of infrastructure and population
Serves as effective communication tool between various
stakeholders
Steps involve:
Creating an inventory of built environment, human exposure,
and economic value
Analysis of potential hazards
Analysis of potential damage
Translation into social and economic loss
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Risk Assessment Methods: Time – based
Probabilistic Assessment
Estimates disaster loss from multiple events and the
probability of occurrence of each event in time
Analytically most sophisticated
Important for planners to understand the concepts of
probabilistic assessment
Forms basis for: building code regulation, micro-zoning,
benefit/cost analysis of risk reduction options
Used to establish a threshold for acceptable risk
Provides spatial distribution of severity of various hazards
at a high level of resolution
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Using the Results: Establishment of Basic
Planning Parameters
Based on participatory approach to:
Establish level of acceptable risk
Establish priorities
Set planning strategies and interventions
Look at options to reduce risk:
Transfer or share
Eliminate or avoid
Accept, or retain and manage
Mitigate
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Monitoring Implementation
Continuously monitor status of risk and interaction with
land use
Factor into risk assessment and land use planning process
the changes in risk
Check the effectiveness of land use planning measures in
reducing risk by:
Using monitoring and evaluation forms
Scheduling regular monitoring activities
Assigning responsible parties
Submitting progress reports
Using indicators and benchmarks
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Challenges to Risk Assessment
Multiple hazards to which people are simultaneously exposed
Difficulty in aggregating vulnerability across sectors
Wide range of assets to be accounted for in measuring vulnerability and capacity
Large number of stakeholders with roles to play in shaping risk
Unequal access to technology, Inequality in the distribution of human resources,
as well as hardware and inability to buy in data from private sources
Focus on built assets at risk and less on people
Difficulty of measuring human vulnerability
Rapid changes in slums and low-income settlements
Inability to include highly vulnerable populations in assessments
Difference in expert risk assessments and public perceptions of risk
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