1. COMRISK Sub-Project 8 Lincshore: Risk Management Options Pete Floyd, Risk & Policy Analysts Ltd., working with Halcrow and the Environment Agency

2. RPA Approach ● Step 1: Review Halcrow Strategy Review ● Step 2: Explore key risk issues ● Step 3: Develop refined risk assessment methodology ● Step 4: Disseminate results

3. What has happened

4. Why? Grain Size! ● Simply stated: 0.2 mm (before) + 0.6 mm (emplaced) = 0.4 mm by 2001 ● But mixture of grain sizes leads to natural sorting with mean sizes of 0.42 mm, 1.2 mm and 0.27 mm on upper, middle and lower beaches respectively ● Slopes can be readily predicted using Dean expressions: h = A x 2/3 where A = 0.21 D 0.48 ● to give slopes of 1:19 and 1:52 for middle and lower beaches (as previous slide)

5. Current Proposals

6. Where do you place the sand? (Risk Management Options) ● Locations of dVmax ● Minimum standard of defence ● Risks to people ● Risks to property ● Combination of above

7. Standard of Defence ● Essentially, standard is function of wave climate, berm width, sea wall, etc. ● Reviewed profiles from April 2002 and associated overtopping calculations (for 1 in 200 year event) ● Difficult to reconcile!

8. Variations in Key Parameters

9. Is Likelihood of Flooding a Function of Berm Width?

10. Risks to People ● Risks to people function of flood likelihood, wave depths/velocity, area vulnerability (type of housing), people vulnerability, etc. ● Methodology being developed in parallel research for Environment Agency ● BUT also need to resolve earlier issues relating to flood likelihoods

11. Risks to Property ● In Strategy Review, used ‘Risk Reservoirs’ ● Damages calculated for residential, caravans, industrial and agricultural damages for each reservoir for each option under different conditions

12. Sample Damages by Reservoir

13. Difficulties ● Risk management of frontages will rely on being able to determine damages of events from each frontage rather than across whole coast ● Clearly, would require extensive modelling work to generate ‘damage risk contours’ ● As before still need to relate flood potential to beach profiles

14. Conclusions ● 10 years on, beach profiles are not as designed due, primarily, to grain size distribution of emplaced sand ● Modified profile accounted for in current proposals ● However, developing practical risk management options has proved to be a complex process