1. 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 McKenzie
BRISBANE, AUSTRALIA | SEPTEMBER 2017
MANAGED BY

2. Outline
Background
Approach
Results
Conclusions

3. Background Why assess future flood risks at a national scale

4. Ten golden rules of strategic flood risk Management
(Sayers et al., 2014)

5. UK Climate Change Act 2008 The UK Climate Change Act requires
The 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 programme
The first CCRA was completed in 2012
The second CCRA is due for publication 2017
The evidence provided on future flood risk is the subject this talk

6. Approach To assessing future flood risk at a UK scale through to the 2080s

7. An all sources approach: Flood hazards
Fluvial Tewksbury, UK July 2007
Coastal
West Bay, Dorset, October 2004
Taken by: West Dorset District Council
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

8. System descriptors Sources Pathways Receptors
Drivers of exogenous change
change
Climate change
Rainfall
Short duration(<6hrs)
Longer duration
Sea level rise
Deterioration of defences / levees
Population growth and household occupancy
Risk = f(chance and consequences)
Property
Business
People
Agriculture
Critical infrastructure Natural capital
System descriptors
Extremes rainfall and
sea levels
Hydrological and hydraulic processes
Exposure and social vulnerability
Whole system analysis (Future Flood Explorer)
Sources
Pathways
Receptors
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
Endogenous responses
change

9. UK Future Flood Explorer
An emulation approach that brings together spatially explicitly data on
Flood probability
Flood defences

10. UK Future Flood Explorer
An emulation approach that brings together spatially explicitly data on
Flood probability
Flood defences
Receptors

11. Alterative adaptation scenarios

12. Results So how do risks change and what impact does alterative levels of adaptation have?

13. Example results: Change in EAD (£)
H++ Future: Low growth
2oC Future: Low growth
4oC Future: Low growth

14. Example results: EAD (£) through time
Expected Annual (direct) Damages (EAD) The UK through time

15. Some example: EAD by source
Expected Annual (direct) Damages (EAD)
The UK through time By
Source
Top: 2oC low growth
Bottom:4oC low growth

16. Example results Summary contribution to risk (2050s)
And
Ability for adaptation to reduce risk
Top: 2oC low growth
Bottom:2oC high growth

17. 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

18. The contribution to risk reduction from individual measures as part of a portfolio (Example for Cumbria, Sayers and Horritt, 2016)

19. 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°C
150% under 4°C
The 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

20. 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 change
This involves a portfolio of responses to manage probability, exposure and vulnerability

21. Conclusions And where next for the UK Future Flood Explorer itself..
The FFE is well suited to large scale analysis and exploration of alternative futures
Recent extensions to explore issues of social justice in flood risk management in the UK
International development and applications, we are currently developing the Awash FFE.

22. Acknowledgements and references
Further detail
Sayers et al, Climate Change Risk Assessment 2017: Future flooding report.
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
Skype: floodsman Telephone: