Transcript Thames Pilot Study

ESPACE:
Decision Testing Framework
Thames Pilot Study
Tim Reeder & Bill Donovan,
Environment Agency
Jon Wicks, Halcrow
Structure of talk
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Challenges of flood risk management in the
Thames Estuary
UKCIP decision making framework
Application of the framework to the Thames
Estuary
The Thames Estuary
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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
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200 years of
Rising Sea Levels
at Canvey Island
The Lobster Smack in
1902: the defences
were described at the
time as being
“practically invulnerable”
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 future view for London?
Interim Defences during the construction of the Thames Barrier >
1928 Flood & subsequent 1930 Flood Act >
Late C19 update to Flood Act >
1879 Flood Act >
Thames Estuary 2100 Project
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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
FORESIGHT FUTURES
• World Markets
• 1.25million people
• £80bn Property
• International Habitats & Species
• Port of London generates £2.7bn/yr.
• National Enterprise
- 400 Schools, 16 Hospitals
- 30 Mainline Railway Stns
- 68 Underground & DLR Stns
- 8 Power Stations
• Global Sustainability
• Local Stewardship
337kms of Defences
Thames Barrier
• At Risk
Possible Responses
• The Current Defences
• Control structures/walls • Adapting behaviour & expectation
• Climate change will increase the risk
• Flood water storage
• Future Scenarios
• Flood event management
Thames Estuary 2100 Project
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To achieve the project objectives we have
based our programme of studies around the
UKCIP Decision-Making Framework…
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www.ukcip.org.uk
Helps deliver
policies and
projects that are
robust in the face
of an uncertain
future climate
Eight-stage decision-making framework
The decision-making framework:
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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
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Currently in
steps 2 to 5
Steps 2 to 5 iteration
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2 Establish decisionmaking criteria
3 Assess risk
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5 Appraise
options
4 Identify
options
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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
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2 Establish decisionmaking criteria
3 Assess risk
5 Appraise
options
4 Identify
options
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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.
High level economic appraisal
Define appropriate cost benefit
calculation framework
Define appropriate risk
analysis framework
MDSF analysis: test strategic options under climate
change scenarios (2000, 2050, 2100) => AAD
MDSF Economic direct flood
damages analysis
Broadscale ISISTUFLOW simulation
to generate flood
depth grids
MDSF Social impact analysis
Repeat for each scenario
Export MDSF
results
Estimate costs
of interventions
Consequential
losses
Short social /
environmental analysis
Analysis and reporting
Short uncertainty
analysis
Estimate of flood
fatalities
MDSF
- System Overview
MDSF Customised GIS & Database
Databases
Data:
Background maps
Existing flood maps
DEM
Property data
Land use
Environmental
Coastline
Etc
Local Data:
Local reports
Etc
General Features:
Import & store data
Case/scenario management
Metadata
Generate views
Case Definition:
Climate
Land use
 Policy
Flood Mapping:
Import water levels
Generate (or import) flood
depth grids
Coastal Erosion:
Import erosion contours
External ‘tools’
to provide:
(1) flood
depths
(optionally
extents)
(2) erosion
contours
Outputs
(electronic plan s?)
Economic Analysis:
Flood damages
Erosion damages
Social Impacts:
People affected
Social flood vulnerability
Further analysis, iteration,
consultation and review
leading to:
Policy Evaluation:
Compare baseline with
scenarios
CFMP / SMP
Strategy Plan
Uncertainty Estimation:
Acknowledge and estimate
uncertainty
Repeat for all ‘cases’
ISIS-TUFLOW broad
scale flood model
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Could show 10m tuflow – greenwich?
Shows use of same tools at greater detail
Findings
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4 strategic options tested:
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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
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Currently working on further iterations
• High
level economic
appraisal (strategic
options) 
• Early conceptual
options
• High level options
Stakeholder engagement
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Send results to FloodRanger
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More text here
FloodRanger & FloodRanger Pro
Conclusions – to be written
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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