FLOOD site Results on Flood Risk Analysis

1. FLOODsite Results on Flood Risk Analysis A. KortenhausLWI, Braunschweig, Germany

2. Contents • Concept & Objectives • Results • Risk Sources • Risk Pathways • Risk Receptors • Conclusions WG-F Meeting Brussels

3. Concept & Objectives

4. Source-Pathway-Receptor model Source Pathway Receptor WG-F Meeting Brussels

5. Source Receptor Pathway Urban Infrastructure Sea (storm surge + waves) Agriculture Flooding Dikebreaching Flooding Industry Flooding Flooding Flooding Estuary (storm surge + river discharge) Storm surge Flood defence structure Flood prone area WG-F Meeting Brussels

6. Predicted Flooding Probability Pfc Expected damages E(D) Predicted Flood Risk Evaluation of „Toler- able“ Risk Residual Flood Risk Risk Analysis • Risk Sources •       • Storm surge • River discharge • Heavy rainfall • Risk Pathways •       • Loads & Resistances • Defence failures • Inundation • Risk Receptors •       • People & property • ecological impact • Risk perception WG-F Meeting Brussels

7. Objectives • Improve understanding of the primary drivers of flood risk, incl. uncertainty • Improve understanding, models and techniques for the analysis of the performance of the whole flood defence system and its diverse components • Understand the vulnerability of the receptors of risk and improve the methods to evaluate societal consequences Source Pathway Receptor WG-F Meeting Brussels

8. Risk Sources

9. Flash Floods WG-F Meeting Brussels

10. River Floods WG-F Meeting Brussels

11. Coastal Floods WG-F Meeting Brussels

12. Flash floods Discharge Inland Rainfall River floods Discharge Estuary Coastal floods Water level& waves Storm surge Coast Earth- quake Tsunamis Waves Time Key factors WG-F Meeting Brussels

13. Sub-Theme 1.1: Risk Sources Available models and previous proj. Data from pilot application sites Data from national sites Flash Floodhazards 1 Estimationof extremes 2 Flood hazard atlas 3 Hydrological / hydraulic boundary conditions, incl. uncertainties & focusing on extremes and joint probabilities Methodology for mapping of results Tasks 12, 15, 16, 23 (flash flood) Loading & resistance of each defence structure WG-F Meeting Brussels

14. Required steps Rainfall River Discharge Water Levels Waves Data availability? Homogeneity of Data? Data Correlation? Extrapolation to Extremes? Statistical Tools Probability Density Function Joint Probabilities of Parameters WG-F Meeting Brussels

15. Risk sources: challenges • gaps in time series (e.g. broken water level gauge) • available length of time series, resampling methods (e.g. Bootstrap) • trend analysis (e.g. secular sea level rise) • morphodynamic influence (e.g. offshore sand bars) • probability density functions (e.g. Generalised Pareto) WG-F Meeting Brussels

16. Extreme Events • New methods and data to deal with extreme values, incl. their statistical distributions and joint probabilities • Gaps • consider inhomo-geneity of data • determination & presentation of error bounds Source: Galiatsatou, P. et al. (2008): Estimation of extremes: conventional versus Bayesian techniques. Journal of Hydraulic Research, vol. 46, Extra Issue 2, pp. 211-223. WG-F Meeting Brussels

17. Flood Hazard Mapping • Review of existing flood hazard mapping technologies and recommendations for coastal flood hazard mapping • Gaps • focus on coastal flooding only • transfer might be difficult due to the specific nature of different flood hazards Source: Jimenez et al. (2008): Recommendations on Coastal Flood Hazard Mapping, Final Report, FLOODsite - Integrated Flood Risk Assessment and Management Methodologies, Report no. T03-08-02, Task 3. WG-F Meeting Brussels

18. Risk Pathways

19. Pathways – Flash Floods WG-F Meeting Brussels

20. Pathways - River WG-F Meeting Brussels

21. Pathways - Coast WG-F Meeting Brussels

22. Sub-Theme 1.2: Risk Pathways jpdf from risk sources Data from pilot application sites Available models and previous proj. 5 Morphological changes 4 Loading & failure modes 8 Flood inundation Breaching 6 7 Reliability analysis: Pf Performance of entire defence system and its components, incl. breach growth, flood wave propagation & inundation Sub-Theme 1.3 Theme 2 Theme 3 Theme 4 WG-F Meeting Brussels

23. Risk Pathways: Required steps • Identify sections of defence line • Identify defence line elements for each section • Identify failure modes for each element • Failure probabilities for each failure mode • Setup fault tree for each element • Overall failure probability of element • Flooding probability of defence line WG-F Meeting Brussels

24. Failure Modes of Flood Defences • Consistent catalogue of flood defence struc-tures and related failure modes • Gaps • Extension of ca-talogue required • length effect of structures • transitions • animal burrows Source: Allsop, N.W.H.et al. (2006): Failure mechanisms for flood defence structures. FLOODsite - Integrated Flood Risk Assessment and Management Methodologies, Task 4, 150 p. WG-F Meeting Brussels

25. Breaching of dikes & embankments • Model tests and numerical models for breaching of sea dikes and river embankments • Gaps • breach initiation • soil erodibility • forecast for time & location • breach models in systems analysis WG-F Meeting Brussels

26. Reliability of Systems • New consistent approaches and computer model to determine flooding probabilities • Gaps • consider time depen-dency of failure modes • correlation of sections in system analysis • complex numerical models to be used in reliability analysis Source: Van Gelder, P.H.A.J.M. et al. (2008): Reliability analysis of flood sea defence structures and systems. FLOODsite - Integrated Flood Risk Assessment and Management Methodologies, Report no. T07-08-01, Task 7, 118 p. WG-F Meeting Brussels

27. Risk Receptors

28. Risk Receptors WG-F Meeting Brussels

29. Risk Receptors WG-F Meeting Brussels

30. Sub-Theme 1.3: Risk Receptors Flood wave propagation & inundation Data from pilot application sites EU-Guidelines and methods for socio-economic flood damage evaluation 9 10 11 Socio-economic evaluation + modelling Risk perception, comm. behaviour and resilience Direct / indirect & tangible / intangible losses, incl. degradation and resilience Framework and methods for assessment of flood risk acceptance Theme 2 Theme 3 Theme 4 WG-F Meeting Brussels

31. FLOODsite Results • guidance on socio-economic evaluation of flood damages • loss of life model based on data from river floods • influence of early warning • eco-toxicological modelling of flooding • resilience and community vulnerability • flood preparedness WG-F Meeting Brussels

32. Socio-economic Assessment • Guidelines summarising evaluation methods for tangible socio-economic damages • Gaps • indirect economic costs • intangible damages (en-vironmental and social) • influence of non-structural measures • uncertainties Source: Meyer, V.; Messner, F. (2006): National flood damage evaluation methods – a review of applied methods in England, The Netherlands, the Czech Republic and Germany. FLOODsite, Task 9, Braunschweig, Germany, 44 p. WG-F Meeting Brussels

33. Loss of Life Model • new model based on European river floods, not transferable to coasts • Gaps • more data on different types of floods • transfer to coast and estuaries • improved mapping methodology Source: Tapsell, S.M. et al. (2007): Socio-economic and ecological evaluation and modelling methodologies FLOODsite - Integrated Flood Risk Assessment and Management Methodologies, Task 10, 200 p., 1 Annex. WG-F Meeting Brussels

34. Conclusions

35. Conclusions • Improved understanding of flooding processes and assessment of flood impacts • Merging the worlds of flash floods, river floods, and coastal floods • Contributions to requirements of European Flood Directive • Application and further development of tools within Pilot Sites of FLOODsite WG-F Meeting Brussels

36. Photo: A. Kortenhaus, warning sign, Pilot Site “German Bight Coast” WG-F Meeting Brussels

37. Thank you very much for your attention!