UK floods past, present and future
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Is flooding the new normal? Nick Reynard of the Centre for Ecology & Hydrology presents at the Flood, Risk & Insurance conference October 2015. For more information, see our Natural Hazards science area: http://www.ceh.ac.uk/our-science/science-areas/natural-hazards
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UK floods past, present and future
- 1. UK Floods: Past, Present and Future Nick Reynard – Science Area Lead for Natural Hazards research Centre for Ecology & Hydrology, Wallingford Thanks to Jamie Hannaford, Bob Moore, Steve Cole, Vicky Bell, Alison Kay Wallingford, December 2012Maidenhead, January 2014
- 2. • Introduction to CEH • Natural hazards and floods research • Past events • The future: Is flooding the new normal? Structure ©The Guardian
- 3. Meeting the Challenges of Environmental Change • Securing the Value of Nature • Building Resilience to Environmental Hazards • Managing Environmental Change CEH Strategy 2014 – 2019
- 4. Delivering our Strategy CEH Science and Impact • Excellent • Distinctive • Relevant
- 5. Natural Hazards: Vision Science to improve the understanding and prediction of the threats and impacts posed by natural hazards, and the development of management and resilience strategies. Understand the threats Predict and forecast Manage and mitigate
- 7. Flooding at Wallingford Bridge, January 2014 Centre for Ecology and Hydrology Recent events – winter 2013-14
- 8. Are floods the new normal? Central/Northern England, 2007 England and Wales, 2000 Photos: Environment Agency, NERC, BBC Cockermouth, Cumbria, Nov 2009 Moorland, Somerset Levels, 2013
- 9. Are floods the new normal? 2000 - 2014 • 2000 extensive autumn floods • 2002/3 winter floods in southern England • 2004 Boscastle flood • 2005 Flooding in NW England • 2007 summer floods • 2008 flooding in Northern Ireland & northern Britain • 2009 Floods in Cumbria and eastern Scotland • 2010-12: from drought to floods • 2013/2014 winter floods
- 10. • 1946 Major floods in central Britain • March 1947 – most extensive 20thC flooding in E&W • 1951 Severe groundwater flooding • 1952 Lynmouth Disaster • 1953 Devastating tidal flooding • 1954 Severe flooding in the South • 1955 Martinstown storm (rainfall record to this day) Were floods the old normal? 1946 - 1955 (with thanks to Terry Marsh for the history lesson)
- 11. 2007 1947 1809 1894 1947 2003, 2007, 2014 Historic flood levels on the Thames, Shillingford Thames flood record from Kingston, 1883 - 2014 Are floods becoming more severe? The long view Marsh, Terry and Harvey, Catherine, L. 2012. The Thames flood series: a lack of trend in flood magnitude and a decline in maximum levels. Hydrology Research 43.3, 203-214.
- 12. Persistence of high flows River flows: 30 day annual maxima
- 13. Beware of trends in short records
- 14. National trends in high flows? Hannaford, J. and Buys, G. 2012. Trends in seasonal river flow regimes in the UK. Journal of Hydrology, 475, 158 – 174. Hannaford, J. and Marsh, T.J. 2008. High flow and flood trends in a network of undisturbed catchments in the UK. International Journal of Climatology, 28 (10), 1325 – 1338
- 15. Increased variability? England and Wales National Runoff Series, 2012 Calderdale, Jun/July N. Wales, Nov NE Scotland, Dec All photos © bbc
- 16. The logical case for increases in flood magnitude/frequency • The world is getting warmer • Increased winter rainfall across the UK • Some evidence of increased rainfall intensity • Cluster of recent flood episodes • Some consistency with projections based on climate change scenarios • Natural variability Future floods: climate change
- 17. Changing floods: the evidence http://www.lwec.org.uk/resources/report-cards/water
- 18. Future flood risk Percentage change in 20-year river flow by the 2080s Change %
- 19. Catchment modelling Probabilistic projections (box-and-whisker plots): 10,000 Sampled Data delta changes 100 Weather Generator time-series Regional Climate Model data (points): 11 delta changes (crosses) 11 time-series (rectangles) 9 catchments modelled Teme at Tenbury (54008) 2080s, Medium emissions Kay, A.L. and Jones, R.G. (2012). Comparison of the use of alternative UKCP09 products for modelling the impacts of climate change on flood frequency. Climatic Change, 114(2), 211-230.
- 20. Science for flood management policy • Communication to potential users REGIONALISED IMPACTS OF CLIMATE CHANGE ON FLOOD FLOWS In support of climate change policy and guidelines for flood management • Investigate the impact of climate change on river flows across Britain to assess the suitability of 20% climate change guidance • Investigate catchment response to climate change to identify potential similarities such that the Defra nationwide guidance could be regionalised • Model >150 catchments under 10,000 scenarios of future climate
- 21. 1. How appropriate is the national allowance? Allowance (% change) %ofUKCP09 scenarios 2. What should the new allowance be? Welsh region
- 22. Adapting to Climate Change ADVICE FOR FLOOD AND COASTAL EROSION RISK MANAGEMENT AUTHORITIES EA, AUGUST 2011 Total potential change anticipated for the 2020s Total potential change anticipated for the 2050s Total potential change anticipated for the 2080s Northumbria Upper estimate 25% 30% 50% Change factor 10% 15% 20% Lower estimate 0% 0% 5% H++ scenario 35% 45% 75%
- 23. Flood Risk is more than just high flows Risk = probability x consequence SOURCE PATHWAY RECEPTOR“The Battle for Walham Switching Station”, July 2007 Providing power to 500k homes. The fire brigade, Army, Royal Navy, Royal Air Force and the Environment Agency joined forces to save the power station which came within a few cms of flooding Oxford, July 2007 Wet feet! Providing power to 500k homes
- 24. Historical floods: 1894 ‘One of the sad and yet ludicrous features of a visit to the flooded districts was to see, rising through the water in dozens of localities, posts bearing large posters announcing “Eligible building land to let”. (Symons & Chatterton, QJRMS)
- 25. Historical floods: 1947 ‘Many of the complaints of the flooding of houses came from…lands known to have been flooded many times in the past…The restrictions of building on such areas must be encouraged in the future…’ (Howarth, Mowbray et al, JIWE)
- 26. Floods: Past, present and future - Final thoughts "It is commonly observed, that when two Englishmen meet, their first talk is of the weather; they are in haste to tell each other, what each must already know, that it is hot or cold, bright or cloudy, windy or calm.“ Dr Samuel Johnson We live on some islands on the margin of the Atlantic Ocean, with a climate which is inherently variable. Despite widely-held perceptions, there is no compelling evidence to suggest any long-term tendency towards increasing severity or frequency of floods and droughts in the UK However, recent years have been in the extreme ranges of recorded variability and underlined our vulnerability to both drought and flood. Recent hydrological volatility may be indicative of anthropogenic climate change, but it could also reflect natural variability; differentiating the two is a major scientific challenge. Is the past a guide to the future in warming world?
- 27. Thank you! Nick Reynard – Science Area Lead for Natural Hazards research Centre for Ecology & Hydrology, Wallingford ©UnitedUtilities
Editor's Notes
- Main headings for CEH strategy 14-19. Provide draft copies to panel SVN To determine the quality, quantity and risks to natural capital; informing the development of strategies to meet the increasing demands for natural resources. A healthy environment provides food, clean air and water, and countless other inputs to everything we produce and consume, and many essential services such as flood mitigation, pollution and climate regulation, and pest and disease control. This represents natural capital. In exploiting natural capital to generate economic growth, demands on natural systems increase, alongside mounting demographic and environmental change. Monitoring and assessment provides the evidence-base for effective action to safeguard and improve society’s environmental legacy. BRNH To assess risk and exposure to natural and man-made environmental hazards; developing strategies to address threats to society and our environment. The dependence of modern society on agricultural production, energy supply, chemical use and transport and communication infrastructures, highlights the need for increased resilience to environmental hazards as a high priority. Scientific data are crucial for characterising environmental hazards and how they interact with one another – forming the evidence-base needed to assess the threats posed and how they can be mitigated. MEC Integrate monitoring, process understanding and modelling to assess and respond to threats and risks, and benefit from opportunities associated with natural and humankind led environmental change. Establish early warnings of change and possible ecosystem tipping points Attribute causes and determine interactions between drivers of change such as land-use and climate Identify opportunities for adaptation and build increased resilience of ecosystems to change. To improve the resilience of natural and highly managed systems, policy needs to drive environmental management and must be based on robust scientific evidence.
- Main headings for CEH strategy 14-19. Provide draft copies to panel SVN To determine the quality, quantity and risks to natural capital; informing the development of strategies to meet the increasing demands for natural resources. A healthy environment provides food, clean air and water, and countless other inputs to everything we produce and consume, and many essential services such as flood mitigation, pollution and climate regulation, and pest and disease control. This represents natural capital. In exploiting natural capital to generate economic growth, demands on natural systems increase, alongside mounting demographic and environmental change. Monitoring and assessment provides the evidence-base for effective action to safeguard and improve society’s environmental legacy. BRNH To assess risk and exposure to natural and man-made environmental hazards; developing strategies to address threats to society and our environment. The dependence of modern society on agricultural production, energy supply, chemical use and transport and communication infrastructures, highlights the need for increased resilience to environmental hazards as a high priority. Scientific data are crucial for characterising environmental hazards and how they interact with one another – forming the evidence-base needed to assess the threats posed and how they can be mitigated. MEC Integrate monitoring, process understanding and modelling to assess and respond to threats and risks, and benefit from opportunities associated with natural and humankind led environmental change. Establish early warnings of change and possible ecosystem tipping points Attribute causes and determine interactions between drivers of change such as land-use and climate Identify opportunities for adaptation and build increased resilience of ecosystems to change. To improve the resilience of natural and highly managed systems, policy needs to drive environmental management and must be based on robust scientific evidence.
- Illustration of the structure of CEH –Delivery and management of Science staff, students and fellows Each area led by Science Area Lead ( a CEH senior staff scientist, B3) Oversight by external Science Development Group. “two external” SDG members support each Science Area Lead as critical friends Science Areas CEH will deliver our Strategy through Science Areas underpinned by Long-term Monitoring & Observing Systems, Environmental Informatics, Knowledge Exchange and Innovation. Our Science Areas encompass the spectrum of CEH’s extensive, long-term monitoring and world-class research. They are inter-dependent. Hence, CEH’s researchers will contribute to a number of Science Areas. CEH’s Science Areas encompass both NERC national capability funding and shorter-term external income, principally secured through the UK’s Research Councils, Government Departments and Agencies, the European Commission and industry.
- Interaction – where is this?
- For most catchments, there is a reasonable correspondence between the results from each of the methods. That is, there is generally considerable overlap between the cdfs/boxes, with the median values for a catchment generally within 10% or so of each other. Time-series methods (WG/RCM) generally result in a wider range than the other methods (not surprisingly, due to restrictions of delta change methods in terms of changes in variability), so even if the median is well estimated by the other methods, it may be that the higher percentile impacts are under-estimated, especially for higher return periods.