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
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Risk
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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
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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
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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
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Precision of data
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Time-related factors
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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
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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
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Analysis of:
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Quantifies severity of hazard at a given site
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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
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Geographic Information Systems can be useful
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Step 2: Vulnerability Analysis
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Quantifies the degree of susceptibility of people and assets
to sustain damage under various levels of hazard
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Physical vulnerability varies across a city and depends on the existing
building stock and site conditions
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Socio-economic vulnerability depends on population distribution,
socio-economic status, gender, race/ethnicity, age, nature of economy etc.
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Indicates elements at risk that need land use planning
interventions
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Integrates capacity analysis to estimate protective and coping
capabilities
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Step 3: Risk Analysis
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Combines parameters of hazard and vulnerability to
quantify losses
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Time dependent risk assessment provides basis to
determine acceptable level of risk
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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
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Use analytical
tools
Provides
technical and
financial
parameters for
land use planning
Qualitative
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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
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Performed by
experts
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Requires high
level of technical
expertise
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Relies on
quantitative
methods
Risk Sensitive Land Use Planning
Community-driven
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Participatory in nature
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Incorporate variations in
perception and
acceptability of risk of
stakeholders
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Community-based hazard
and risk mapping
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Vulnerability and capacity
assessments
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Risk Assessment Techniques:
Risk Identification
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Determines hazards that may occur in area
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Identifies and characterizes susceptible elements
to the hazard
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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
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Best for a specific project,
event or area
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Best for parameters that are
difficult to quantify
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Helps planners follow
systematic procedure for
land use decisions
Risk Sensitive Land Use Planning
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Risk Assessment Techniques:
Risk Matrix
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Charts parameters of frequency versus severity of
hazards
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Can be both quantitative
and qualitative
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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
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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:
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Creating an inventory of built environment, human exposure,
and economic value
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Analysis of potential hazards
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Analysis of potential damage
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Translation into social and economic loss
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Risk Assessment Methods: Time – based
Probabilistic Assessment
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Estimates disaster loss from multiple events and the
probability of occurrence of each event in time
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Analytically most sophisticated
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Important for planners to understand the concepts of
probabilistic assessment
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Forms basis for: building code regulation, micro-zoning,
benefit/cost analysis of risk reduction options
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Used to establish a threshold for acceptable risk
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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
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Based on participatory approach to:
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Establish level of acceptable risk
Establish priorities
Set planning strategies and interventions
Look at options to reduce risk:
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Transfer or share
Eliminate or avoid
Accept, or retain and manage
Mitigate
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Monitoring Implementation
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Continuously monitor status of risk and interaction with
land use
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Factor into risk assessment and land use planning process
the changes in risk
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Check the effectiveness of land use planning measures in
reducing risk by:
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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
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Multiple hazards to which people are simultaneously exposed
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Difficulty in aggregating vulnerability across sectors
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Wide range of assets to be accounted for in measuring vulnerability and capacity
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Large number of stakeholders with roles to play in shaping risk
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Unequal access to technology, Inequality in the distribution of human resources,
as well as hardware and inability to buy in data from private sources
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Focus on built assets at risk and less on people
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Difficulty of measuring human vulnerability
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Rapid changes in slums and low-income settlements
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Inability to include highly vulnerable populations in assessments
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Difference in expert risk assessments and public perceptions of risk
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