Climate Change and Flood Risk. Tim Reeder Regional Climate Change Programme Manager

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1 Climate Cange and Flood Risk Tim Reeder Regional Climate Cange Programme Manager

2 Structure of talk Callenges of flood risk management in London & climate cange issues Te TE 2100 Project - Climate Cange & Decision making - emerging results Working wit partners Conclusions

3 Flood Risk in London Tidal Fluvial Urban Groundwater Combination

4 Tidal Flood Risk 1.25 million people 160bn property at risk Present Flood Risk system robust / ig standard Ageing defence infrastructure Increased development pressure 160,000 new omes most in protected floodplain

5 Tames Region Fluvial Flood Risk properties at risk ( on London tribs) 1000 km 2 land - 10% of Region at risk Increased development pressure

6 Climate Cange & Tames Region Climate Cange critical issue for flood risk Main driver of pysical flood risk sources in order of uncertainty:- Waves Flas flooding - convective storms Fluvial Flow Sea Level Rise Surge Joint Probability Uncertainty

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8 Extensive development, concrete cannels We need to create a river corridor so tat tere is more space for rivers to flow and flood naturally Flood risk management needs to be linked to regeneration and redevelopment Resilience and adaptation Integrated approac to manage fluvial, surface water and sewer flooding is needed

9 Urban Flood Risk Making Space for Water Pilot Project Brent Hogsmill

10 Wat is TE2100? A Project to provide a plan demonstrating ow flood risk can be managed in te Tames Estuary over tis century in response to: a canging climate a canging estuary ageing flood defences

11 Tames Barrier Tidal, Fluvially dominated Closures as at (25 Marc 2008) 82/83 83/84 84/85 85/86 86/87 87/88 88/89 89/90 90/91 91/92 92/93 93/94 94/95 95/96 96/97 97/98 98/99 99/00 00/01 01/02 02/03 03/04 04/05 05/06 06/07 07/08 Years Tidal Fluvially dominated No of Closures

12 Tames Estuary 2100 Plan Area >1.25million people 160bn Property International Habitats & Species Port of London generates 2.7bn/yr Scools, 16 Hospitals - 30 Mainline Railway Stns - 68 Underground & DLR Stns - 8 Power Stations 337kms of Defences 4 Climate Cange futures examined Defra UKCIP Med Hig Tames Barrier Hig + Hig ++ At Risk Future Scenarios Restoration of te Floodplain Te Current Defences New Barriers Spatial Planning Controlled Inundation

13 Long-Term Sea-Level Rise 4 x CO 2 experiment 1 and arbitrary WAIS collapse scenario 1. Source: Jason Lowe, te Hadley Centre 20 4 * CO2 experiment Plus Arbituary Total WAIS collapse Sea-Level Rise (m) Arbituary Time (years)

14 Source: Lowe, Hadley Uncertainty in storm surge predictions HadCM2/HadRM2 Gumbel ECHAM4 GEV HadCM3/HadRM3 GEV

15 TE2100 Programme CC studies wit Met Office POL CEH provide probabilistic scenarios for Tames Estuary for Storm Surge, Sea Level Rise, Fluvial Flow. Storm Surge and Sea Level Rise benefit to UKCIP next Need for monitoring - links wit BAS, at cutting edge of ice melt science Climate Cange Critical Factor - 4t Assessment Report Case Study

16 Tames Estuary 2100 Project To acieve te project objectives we ave based our programme of studies around te a Decision-Making Framework tat as largely been piloted by ESPACE

17 Baseline Flood Risk Current 1:1,000 year flood today overtopping only

18 Flooding in 2050 (overtopping) Conservative 1:1000 year flood in s UKCIP Medium- Hig, overtopping only

19 Future Flood Risk Conservative estimate of 1:1000 year flood ( ) UKCIP Medium-Hig, overtopping only

20 Risk Managing Flood Risk troug te century Acceptable level of risk Time

21 Max water level rise: 0m Defra and upper part of new TE2100 likely range 1m Top of new H++ range 2m 3m Previous Extreme 4m HLO 1 Improve Tames Barrier and raise d/s defences HLO 2 Existing system Over-rotate Tames Barrier and restore interim defences Flood storage, improve Tames Barrier, raise u/s & d/s defences Raise Defences Flood storage, over rotate Tames Barrier, raise u/s & d/s defences Flood storage, restore interim defences HLO 3a New barrier, retain Tames Barrier, raise defences New barrier, raise defences HLO 3b HLO 4 New barrage

22 TE2100 Science Key Findings Sea level rise in te Tames over te next century due to termal expansion of te oceans, melting glaciers and polar ice is likely to be between 20cm and 90cm. Tere is still muc uncertainty over te contribution of polar ice melt to sea level rise. At te extreme it may furter raise sea levels up to 2m (including termal expansion) - altoug tis is tougt igly unlikely. Altoug still uncertain, climate cange is less likely to increase storm surge eigt and frequency in te Nort Sea tan previously tougt. Future peak freswater flows for te Tames are also uncertain. At Kingston tey could increase by around 40% by To reduce te uncertainty over te potential effect of polar ice melt on sea level rise, furter researc and monitoring is needed.

23 Implications for TE2100 of latest science Tese results give greater certainty tat we ave been planning for te rigt potential range of water levels tis century We are able to revise down our previous worst-case scenario from increases in maximum water levels of 4.2 metres to 2.7 metres Wit a reduction in worst case scenario for tis century, we are even less likely to require a tide excluding estuary barrage to manage flood risk. We need to test our options for managing flood risk in west London against a potential greater increase in flows tan previously planned for

24 Flood Zone Map (EA Website)

25 Flood Residual Risk Map (SFRA) Hig risk: Significant dept Medium risk Low risk: island Hig risk: Rapid Inundation Zone

26 Building resilience measures in Hamburg

27 Preparedness London Resilience ave prepared a Strategic Flood Response Plan for London RFRA identifies infrastructure tat may be at risk RFRA identifies need for spatial planners and emergency planners to work togeter

28 Conclusions Climate cange will be te major cause of increased flood risk in te future. Ongoing monitoring to detect trends / tipping points Flood defences cannot protect everyting. Te floodplain is our biggest asset in managing flood risk. Planning is critical - links to emergency planning. Benefit of stabilisation / mitigation - significant cost savings TE2100 will produce an adaptable plan wic will be resilient to an uncertain future