Date post: | 18-Dec-2015 |
Category: |
Documents |
Upload: | estella-wilkerson |
View: | 219 times |
Download: | 0 times |
National Centre for Risk Analysis and Options Appraisal
Risk Assessment, RASP and Risk Assessment, RASP and IMPACTIMPACT
Ian Meadowcroft
National Centre for Risk Analysis and Options Appraisal
Meanings of RiskMeanings of Risk
• Combination of likelihood and consequences of specified outcome
• Likelihood - usually annual probability
• Outcomes include flooding, damage (properties / infrastructure), effects on people, environmental harm
• Individual and aggregate risk
• Concepts / definitions / tools reviewed in SR587
National Centre for Risk Analysis and Options Appraisal
Conceptual Model: Source - Conceptual Model: Source - Pathway - ReceptorPathway - Receptor
RECEPTORS: people, property,warning effectivenessSOURCE - High river,
Tide, Waves
PATHWAY: Defenceoperations, flooding
National Centre for Risk Analysis and Options Appraisal
Risk-based decision-makingRisk-based decision-making
• New defences
• Maintaining and operating defence systems
• Flood warning
• Restricting development in flood and erosion prone areas
• Strategic planning, policy analysis
National Centre for Risk Analysis and Options Appraisal
Risk-based decisions.....Risk-based decisions.....• What is the national / regional risk?
• What is the appropriate level of spending to reduce risk?
• Which reach / defence poses the greatest risk?
• Where are the maintenance priorities?
• What impact might climate change have?
• What combination of risk management most effective?
• What is the ‘residual risk’, how will it change?
National Centre for Risk Analysis and Options Appraisal
RASP - Risk Assessment for RASP - Risk Assessment for Strategic PlanningStrategic PlanningRASP methodology will deliver:
• Failure probabilities for individual defences
• Failure probabilities for the defence “system”
• Total flood risk for identified community (impact zone)
• An indication of the risk associated with each defence (using information on failure probability and consequences - economic or social)
National Centre for Risk Analysis and Options Appraisal
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
P(B¦OT, CG=1)
P(B¦OT, CG=2)
P(B¦OT, CG=3)
P(B¦OT, CG=4)
P(B¦OT, CG=5)
Estimate the probability of overtopping and breaching for each defence section
Loading
Condition Good
Condition PoorProbability ofBreach
National Centre for Risk Analysis and Options Appraisal
Risk: Annual Average Damage in each land use zone
National Centre for Risk Analysis and Options Appraisal
Approach to Risk AssessmentApproach to Risk Assessment