MANAGED BY Assessing future flood risk and opportunities for adaptation at UK scale Paul Sayers Sayers and Partners SPL AssociateAdvisor WWF and Reserach Fellow University of Oxford Coauthors Matt Horritt Edmund PenningRowsell and Andrew McKenzie ID: 635252
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BRISBANE, AUSTRALIA | 18 - 20 SEPTEMBER 2017
MANAGED BY
Assessing future flood risk and opportunities for adaptation at UK scale
Paul Sayers
Sayers and Partners (SPL), Associate-Advisor WWF and Reserach Fellow, University of Oxford.
Co-authors Matt Horritt, Edmund Penning-Rowsell and Andrew McKenzieSlide2
Outline
BackgroundApproachResultsConclusionsSlide3
BackgroundWhy assess future flood risks at a national scale
3Slide4
4
Ten
golden
rules
of
strategic flood
risk Management(Sayers et al., 2014)Slide5
UK Climate Change Act 2008
The UK Climate Change Act requiresThe Climate Change Committee to undertake a Climate Change Risk Assessment (the CCRA) every 5 years and then produce a policy programme to address those risks The Adaptation Sub-Committee
advises on this assessment and scrutinises the implementation of the policy programmeThe first CCRA was completed in 2012The second CCRA is due for publication 2017 The evidence provided on future flood risk is the subject this talk
5Slide6
Approach To assessing future flood risk at a UK scale through to the 2080s
6Slide7
An all sources approach: Flood hazards
FluvialTewksbury, UK July 20077
Groundwater
Berkshire, March 2014
Taken by: A McKenzie
Permeable Superficial Deposits
Clearwater (Chalk and other aquifers)
Surface water
Bristol road, Birmingham, 2000
Taken by: John
Blanksby
Coastal
West Bay, Dorset, October 2004
Taken by
: West Dorset District CouncilSlide8
Drivers of exogenous change
Climate change
Rainfall
Short duration(<6hrs)
Longer duration
Sea level riseDeterioration of defences / levees
Population growth and household occupancy
Extremes rainfall andsea levels
Sources
Hydrological and hydraulic processes
Pathways
Exposure and social vulnerability
Receptors
System descriptors
Excluded here
Probability:
Formal defences
Coastal foreshore management
Rural land management
Urban surface water management
Exposure:
Spatial planning
Vulnerability:
Property level protection
Forecasting and warning
Risk = f(chance and consequences)
Property
Business
People
Agriculture
Critical infrastructure Natural capital
change
change
Whole system analysis (
Future Flood Explorer)
Endogenous responsesSlide9
UK Future Flood Explorer
An emulation approach that brings together spatially explicitly data onFlood probabilityFlood defences9Slide10
UK Future Flood Explorer
An emulation approach that brings together spatially explicitly data onFlood probabilityFlood defencesReceptors10Slide11
Alterative adaptation scenarios
11Slide12
ResultsSo how do risks change and what impact does alterative levels of adaptation have?
12Slide13
13
Example results: Change in EAD (£)
2
o
C Future: Low growth
4
o
C
Future: Low growth
H++
Future: Low growthSlide14
14
Example results: EAD (£) through timeExpected Annual (direct) Damages (EAD)The UK through time Slide15
15
Some example: EAD by source
Expected Annual (direct) Damages (EAD)
The UK through time
By
Source
Top: 2
o
C low growth
Bottom:4
o
C low growthSlide16
16
Example results
Summary contribution to risk (2050s)
And
Ability for adaptation to reduce risk
Top: 2
o
C low growth
Bottom:2
o
C high growthSlide17
A focus on vulnerable coastal defences
Left: Highly vulnerable defences and temporary inundation extent under a 1:200 year return period tidal surge and a range of assumed values of sea level rise
Bottom:Relationship between SLR and length of highly vulnerable defences
17Slide18
The contribution to risk reduction from individual measures as part of a portfolio (Example for Cumbria, Sayers and
Horritt, 2016)18Slide19
Conclusions
If we ‘carry on’ as we are how do risks change?Increases in flood risk are projected to occur as early as the 2020s and significantly by 2080s:50% under 2°C150% under 4°CThe increase varies across the UK; in some regions three times greater than in others. Climate change is the main driver of increased risk, population growth is much less important
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Conclusions
If we adopt a more ambitious approach to adaptation what is the impact on future flood risk? Enhanced Whole System adaptation can offset all the increase in risk under the 2°C climate change and low population growth projection, or 70% of the increase in risk associated with the 4°C climate changeThis involves a portfolio of responses to manage probability, exposure and vulnerability
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Conclusions
And where next for the UK Future Flood Explorer itself..The FFE is well suited to large scale analysis and exploration of alternative futuresRecent extensions to explore issues of social justice in flood risk management in the UKInternational development and applications, we are currently developing the Awash FFE.
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Acknowledgements and references
Further detail
Sayers et al, Climate Change Risk Assessment 2017: Future flooding report.
https://www.theccc.org.uk/publication/sayers-for-the-asc-projections-of-future-flood-risk-in-the-uk/
Funding
Primarily provided by NERC via the Committee on Climate Change for the CCRA. The NERC
FoRUM
(Grant NE/M008851/1) supported the use of the FFE in the validation of the national scale risk analysis for England.
Contact
Paul Sayers
Paul.sayers@sayersandpartners.co.uk
Skype:
floodsman
Telephone: 01865 600039