Identifying how the strategies used to evaluate flood damage can affect the results of the evaluation

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Carmel Hamilton
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1 Identifying how the strategies used to evaluate flood damage can affect the results of the evaluation Julian ELEUTERIO (1)(2) Anne ROZAN (1), Robert MOSE (2) (1) UMR Cemagref/ENGEES Management of Public Utilities, France (2) UMR CNRS/UdS/ ENGEES Mechanical Institute of Fluids and Solids UTR Urban Hydraulics, Strasbourg, France

2 Summary Context Objetives Methodolody Results and Perspectives 2

3 Context 3

4 Generalities on flood risk Flood risk management (reduction of overall losses) Decision-making process: cost/benefit and multi-criteria analysis... Flood damages in France 1/3 of municipalities concerned. flood losses represent 80 % of damages associated to natural hazards (250 M per year in average) Absence of national standard methods to evaluate damages of future floods (forecasting) 4

5 Evaluation of future flood damages in practice Great majority of studies consider only part of total damages caused by floods (ex. buildings and contents) Methods, models are generally determined in function of budget restriction and data availability. Uncertainty rarely discussed and studied 5

6 Objectives 6

7 Scientific: Develop a research framework to analyze the impact of different strategies used to evaluate flood damages on the feasibility of the evaluation and on the accuracy of its results Practical: Support the application of future flood damage assessment methods 7

8 Methodology 8

9 Evaluating future floods damage potential Pre-study Future Flood damage EVALUATION PROCESS 9

10 Evaluating future floods damage potential Pre-study Future Flood damage EVALUATION PROCESS 10

11 Pre-study Flood damage Flooding phenomenon data 2 Flood system Definition of objective Land-use and vulnerability data Past damages data and damage functions Urban system 11

12 Pre-study Flood damages Estimate the area for direct damage evaluation Determine damage-functions for each asset type 1 Flood system Definition of objectives 3 Urban system 6 Determine types of damage and the area for indirect damage evaluation 12

13 Pre-study Determine strategies to model flood hazard 8 Flood damage 10 Determine data storage and processing software Flood system Definition of objectives 3 Urban system 6 9 Determine strategies to assess assets vulnerability to floods 13

14 Objectives Methodology Perspectives Pre-study (3C method) Determine strategies to model flood hazard Estimate the area for direct damage evaluation Flooding phenomenon data Flood system Flood damage 1 Definition of objectives Determine data storage and processing software Determine damage-functions for each asset type Past damages data and damage functions Urban system Land-use and vulnerability data 6 Determine types of damage and the area for indirect damage evaluation 9 Determine strategies to assess assets vulnerability to floods 14

15 Objectives Methodology Perspectives Evaluating future floods damage potential Pre-study Future Flood damage EVALUATION PROCESS Uncertainties Based on the evaluation objectives & data availability: Typology of damage Scale of evaluation Required data assessment methods Models and methods to be used 15

16 Evaluating future floods damage potential Pre-study Future Flood damage EVALUATION PROCESS 16

17 Evaluation process 1 st STEP 17

18 Evaluation process 2 nd STEP 1 st STEP 18

19 Evaluation process 2 nd STEP 1 st STEP 3 rd STEP 19

20 Evaluation process PRE-STUDY Accuracy of DATA 2 nd STEP 1 st STEP 3 rd STEP 20

21 Evaluation methodology Hydrologic Hydraulic Geospatial Buildings and contents vulnerability Networks vulnerability Flood system HAZARD GIS-based analysis Urban system VULNERABILITY Flood damage 21

22 Correlating feasibility with uncertainty potential Hydrologic Hydraulic Geospatial Change strategies Buildings and contents vulnerability Networks vulnerability Flood system HAZARD GIS-based analysis Urban system VULNERABILITY Flood damage 22

23 Correlating feasibility with uncertainty potential Hydrologic Hydraulic Geospatial Change strategies Buildings and contents vulnerability Networks vulnerability Flood system HAZARD GIS-based analysis Urban system VULNERABILITY Measure variability Flood damage Measure variability 23

24 Results and Perspectives 24

25 Methodological & Operational Pre-study Future Flood damage EVALUATION PROCESS 25

26 F.R.A. GIS extension v.1 26

27 Results variability Based on case studies Construction of hydrodynamic scenarios FRANCE Urban Community of Strasbourg Fislis Alsace Assessment of buildings and networks vulnerability 27

28 Identifying how the strategies used to evaluate flood damages can affect the results of the evaluation Julian ELEUTERIO (1)(2) Anne ROZAN (1), Robert MOSE (2) (1) UMR Cemagref/ENGEES Management of Public Utilities, France (2) UMR CNRS/UdS/ ENGEES Mechanical Institute of Fluids and Solids UTR Urban Hydraulics, Strasbourg, France

29 ANNEXES

30 EAERE 2009 presentation

31 Damages For floods with different return periods: D ( ΣD ) + ( Σ ) residentia D 1, 5 = l activities D residential = damages to residential buildings D activities = damages to commercial, industrial and other buildings 31

32 Results: Potential damages ( ) GREAT UNCERTAINTY 10 years 30 years 100 years 32

33 Damages Annual Average Costs (AAC) AAC = D ( q) 0 F( q) dq D(q) = total damage caused by a flood (q) with frequency (F) F(q) = frequency of the flood (q) 33

34 Results: Average Annual Cost ( /year) Dependent on expert opinion 34

35 Average Annual Costs

36 Damage-functions

Automating the evaluation of flood damages

Automating the evaluation of flood damages (GSP) Management of Public Utilities / (IMFS) Mechanical Institute of Fluids and Solids Ecole Nationale de l Eau et de l Environnement de Strasbourg / Cemagref / CNRS / UdS Automating the evaluation of