ESPACE: Decision Testing Framework Thames Pilot Study
Tim Reeder & Bill Donovan, Environment AgencyJon Wicks, Halcrow
Structure of talk� Challenges of flood risk management in the
Thames Estuary� UKCIP decision making framework� Application of the framework to the Thames
Estuary
The Thames Estuary� 1.25 million people £80bn property at risk � Ageing defence infrastructure� Increased development pressure
� 160,000 new homes – most in protected floodplain� Impacts of climate change include
� Southend max level (say +1m 2050, +2m 2100)� Fluvial flows, +20%? to 2050
200 years of Rising Sea Levels at Canvey Island
The same building in 2002: the defences, raised following the 1953 flood and raised further in the 1980s are now level with the roof eaves
The Lobster Smack in 1902: the defences were described at the time as being “practically invulnerable”
??? 2100 defences
The future view for London?
1879 Flood Act >>
Late C19 update to Flood Act >
1928 Flood & subsequent 1930 Flood Act >>Interim Defences during the construction of the Thames Barrier >>
Thames Estuary 2100 Project� Aim:
� Develop a flood risk management plan for London and the Thames Estuary for next 100 years
� Addressing:� Management of estuary from a risk
perspective and a ‘whole society’ approach
• At Risk• The Current Defences
• 1.25million people - 400 Schools, 16 Hospitals• £80bn Property - 30 Mainline Railway Stns• International Habitats & Species - 68 Underground & DLR Stns• Port of London generates £2.7bn/yr. - 8 Power Stations
Thames Barrier
• Climate change will increase the risk• Future Scenarios
• Control structures/walls• Flood water storage
337kms of Defences
• Adapting behaviour & expectation• Flood event management
FORESIGHT FUTURES
• World Markets
• National Enterprise
• Global Sustainability
• Local Stewardship
Possible Responses
Thames Estuary 2100 Project� To achieve the project objectives we have
based our programme of studies around the UKCIP Decision-Making Framework…
� Helps deliver policies and projects that are robust in the face of an uncertain future climate
www.ukcip.org.uk
Eight-stage decision-making framework
The decision-making framework:� Directs you to undertake rapid risk
characterisation and screening exercises before deciding to spend more time/money on more detailed risk assessment
� Helps you refine the problem and objectives and modify your options before making a decision
� Guides you to review a decision
Application to Thames Estuary� Currently in
steps 2 to 5
2 Establish decision-making criteria
3 Assess risk
4 Identify options
5 Appraise options
� Expect 3 iterations:� High level economic appraisal
(strategic options)� Early conceptual options� High level options
� Leading to Thames Estuary Flood Risk Management Plan
� Further work to implementation.
Steps 2 to 5 iteration
2 Establish decision-making criteria
3 Assess risk
4 Identify options
5 Appraise options
� Detail increases with each iteration, as:� Better data become available� Decision-making criteria
become better established� Increased stakeholder
involvement� But basic decision-making
framework (and many underlying tools) remain the same.
Steps 2 to 5 iteration
Define appropriate risk analysis framework
Define appropriate cost benefit calculation framework
Estimate costs of interventions
Consequential losses
Short uncertainty analysis
MDSF analysis: test strategic options under climate change scenarios (2000, 2050, 2100) => AAD Broadscale ISIS-
TUFLOW simulation to generate flood
depth gridsMDSF Economic direct flood damages analysis
MDSF Social impact analysis
Repeat for each scenario
Export MDSF results
Estimate of flood fatalities
Analysis and reporting
Short social / environmental analysis
High level economic appraisal
Databases MDSF Customised GIS & Database
Data: Background maps Existing flood maps DEM Property data Land use Environmental Coastline Etc Local Data: Local reports Etc
Outputs
(electronic plans?)
General Features: Import & store data Case/scenario management Metadata Generate views
Coastal Erosion: Import erosion contours
Flood Mapping: Import water levels Generate (or import) flood depth grids
Economic Analysis: Flood damages Erosion damages
Social Impacts: People affected Social flood vulnerability
Policy Evaluation: Compare baseline with scenarios
Uncertainty Estimation: Acknowledge and estimate uncertainty
Case Definition: Climate Land use Policy
Further analysis, iteration, consultation and review leading to:
CFMP / SMP
Strategy Plan
MDSF - System Overview
External ‘tools’ to provide: (1) flood
depths (optionally extents)
(2) erosion
contours
Repeat for all ‘cases’
ISIS-TUFLOW broad scale flood model
� Could show 10m tuflow – greenwich?� Shows use of same tools at greater detail
Findings� 4 strategic options tested:
� 1 - Do nothing (walk away & leave barriers open)� 2 - Maintenance only – declining standards� 3 - Do ‘something’ A giving 1:1000 protection� 4 - Do ‘something’ B giving 1:5000 protection
� Analysis shows high benefit/cost ratios for 2, 3 & 4� But not sufficient ‘detail’ to:
� Select best strategic option� Understand benefits of spatially varying standard
� And no information on actual interventions
Currently working on further iterations� High level economic
appraisal (strategic options)
� Early conceptual options
� High level options
Stakeholder engagement� Send results to FloodRanger
� More text here
FloodRanger & FloodRanger Pro
Conclusions – to be written� UKCIP - Good framework –generic� Need tools to assess risk� MDSF – � FloodRanger - � Range of details, both spatial and data� But can use same basic framework and tools� Plug for uncertainty analysis to drive where to
go into more detail
Thank you