Dr. Jochen Schanze

1. Structural and non-structural measures for flood risk reduction Results from CRUE’s first research funding initiative Dr. Jochen Schanze Leibniz Institute of Ecological and Regional Development

2. Contents • Overview of CRUE’s first research funding initiative • Systematisation of structural and non-structural measures • Effectiveness and efficiency of non-structural measures • Risk perception and context factors for balancing measures • Conclusions on possible policy impacts

3. Contents • Overview of CRUE’s first research funding initiative • Systematisation of structural and non-structural measures • Effectiveness and efficiency of non-structural measures • Risk perception and context factors for balancing measures • Conclusions on possible policy impacts

4. Objectives of the 1st Call (1st March 2006) • To survey the perception of flood risks on various societal and spatial levels (…) and within different sectors (…) and to work out its influence on flood risk management decisions within a selected set of PARTNER countries • To investigate and compare existing concepts / ideas of flood risk management, with particular regard to the relevance of non-structural measures • To identify and systemise non-structural measures for risk reduction as part of existing flood risk management plans, considering the present importance of these non-structural measures • To investigate and compare existing approaches which quantify the effectiveness and efficiency of non-structural measures, compared to structural measures. …

5. Research projects • Effectiveness and efficiency of early warning systems for flash floods (EWASE) • Efficiency of non-structural flood mitigation measures: "room for the river" and "retaining water in the landscape" (Room for the River) • Flood risk reduction by PReserving and restOring river FLOODPLAINs (PRO_Floodplain) • Simulation of flood risk and non-structural risk management (FloodRisk) • Evaluation of risk perception using experimental graphic semiology (RISKCATCH) • Flood risk management in Small Urban CAtchments (SUCA) • Flood risk management strategies in European member states – Evaluation methodology and context factors (FLOOD-ERA)

6. Contents • Overview of CRUE’s first research funding initiative • Systematisation of structural and non-structural measures • Effectiveness and efficiency of non-structural measures • Risk perception and context factors for balancing measures • Conclusions on possible policy impacts

7. FLOOD-ERA Distinction of SM and NSM • Historical development • Differentiation between structural (SM) and non-structural measures (NSM) occurred in the 1940s - 1950s in the USA • Background: Ecological philosophy emphasised the human adaptation capabilities and questioned the “dikes only” policy • A number of systematisation concepts have been proposed (e.g. Penning-Rowsell & Peerbolte 1994, Marsalek 2000, Petry 2002, Parker 2002, 2007, Olfert & Schanze 2007) • Not all of these concepts stick on the terms “structural measures” and “non-structural measure”

8. FLOOD-ERA Understanding of SM and NSM • Proposed definition • Structural measures (SM) are interventions in the flood risk system based on (structural) works of hydraulic engineering • Non-structural measures (NSM) are all other interventions Note • The systematisation is recommended not to include the intended effects but functions and mechanisms.

9. FLOOD-ERA Proposed systematisation of SM and NSM

10. Contents • Overview of CRUE’s first research funding initiative • Systematisation of structural and non-structural measures • Effectiveness and efficiency of non-structural measures • Risk perception and context factors for balancing measures • Conclusions on possible scientific policy impacts

11. Room for the River Effectiveness of land-use changes on peak runoff - Rambla del Poyo (ES)

12. Room for the River Effectiveness of micro ponds on peak runoff - Rambla del Poyo (ES)

13. Room for the River Flood peak reduction at Poyo basin for different landscape measures • Flood probability with synthetic storms • 6 mm mean areal retention • Increase as a functionof return period

14. Evaluation of model predictive performance as a function of forecast lead-time by analysis of flood forecast ensembles EWASE Efficiency of early warning - Forecast reliability

15. Efficiency of early warning- Avoidable damage ewr factor [-] medium 1 upper bound 0.8 lower bound 0.6 0.4 0.2 0 0 1 2 3 4 5 6 lead time [hours] EWASE • Traisen River basin (Austria): • Calculated risk: 24 Mio €/a (SM neglected) • Indicative uncertainty of risk evaluation ≈ 45% • (based on three established damage functions) • Mitigated damages by meansof early warnings • Early warning reduction factors (ewr) questionnaire based survey of preparedness

16. EWASE Efficiency of early warning- Forecast reliability and avoidable damage

17. FloodRisk Socio-economic scenarios Economic growth and demographic change Floodplain geography Market and planning instruments Land use change model Population demographics and transport network Unconstrained development Damages: People and property Climate scenarios Development primarily on brownfield land Loading conditions Engineering interventions Flood risk analysis Infrastructure system

18. FloodRisk Exploring effectiveness of policies

19. FLOOD-ERA Outline Methodology - Procedure • Definition of the scope of the comparative evaluation • Assignment of quantifiedobjective(s) • Measurement of effects, costs and benefits of SM and NSM • Determination and comparison of effectiveness • Determination and comparison of efficiency • Sensitivity analysis • Overallcomparison of SM and NSM

20. FLOOD-ERA Comparison of effectiveness of SM and NSM - Selected results

21. FLOOD-ERA Comparison of cost-effectiveness of SM/NSM - Selected results

22. FLOOD-ERA Comparison of benefit-cost ratio of SM/NSM - Selected results

23. Δ Qfloodplain floodplain 1 floodplain 3 floodplain 2 Δ Qreach PRO_Floodplain Hydrological Criteria of Floodplain Evaluation Parameters Hydromorphology  Peak reduction / increase (ΔQ/km)  Flood wave translation (Δt/km)  River-kilometre related parameters  Secondary effects in case of discharges larger than design discharge  Other processes (sediment, woody debris) Parameters Hydraulics  Water level  Flow velocity  Bottom shear stress  Specific discharge

24. FEM land use PRO_Floodplain Ecological Criteria of Floodplain Evaluation Parameters Ecology  Adapted land use  Dynamics of the water levels  Flow velocity (during inundation)  Surface relief  Connectivity of water bodies  Potential for development of typical habitats  Endangering of valuable habitats

25. Perception of the compatibility between flood retention and nature reserve PRO_Floodplain Sociological Criteria of Floodplain Evaluation Parameters Sociology  Type of usage  Channel of communication

26. floodplain 1 floodplain 3 floodplain 2 PRO_Floodplain Multicriteria Floodplain Evaluation Matrix (FEM)

27. Contents • Overview of CRUE’s first research funding initiative • Systematisation of structural and non-structural measures • Effectiveness and efficiency of non-structural measures • Risk perception and context factors for balancing measures • Conclusions on possible policy impacts

28. FLOOD-ERA Dimensions of strategy development Content • External: • Political • Legal • Social • Economic • General aims and specific targets • Evaluation of measures • Structural and non-structural measures • System analysis: controllable, not • controllable variables • Internal: • Politics • Resources • Responsibility • Culture • Capabilities Process • Models of formulation and implementation: linear, adaptiv • Strategic planning modes: programming, scenario-based planning, etc. • Learning processes at different levels: individual, group, organisation, network Societal context Hutter & Schanze (2008)

29. RISKCATCH Risk communication to the people- Experimental graphic semiology • Presentation of risk maps to different stakeholder groups • Record of eye movements and analysis: • Statistical • Spatial • Dynamic • Cognitive

30. RISKCATCH The perfect risk map Title: in top and not too far away from the legend Background of map: of clear and “realistic” color Legend: - With 5 classes, - Range of only one color, - In red - In order of decreasing value - and written sufficiently large + - Contrast between informative elements and background Additional information of limited number Scale 1/2500, preferably graphical 30

31. SUCA Empowering the public for FRM • Findings: • No understanding of the reasons of urban flooding(DE, UK, F) • Insufficient communication with authorities (DE, UK, F) • In denial of flood risk and ignorant of flood mitigation methods (UK) • Unclear about the institutional structure and responsibility (Too many institutions involved) (DE, UK, F) • Actions: • Organized learning (e.g. ILGs) • Create confidence by communication • (“we are not left alone”) • Inform them about their responsibility and how to make their property flood resilient • Affective communication - Apply symbols of flooding (e.g. flood animation) to raise risk awareness (memories came back). • Single agency – one stop shop

32. SUCA Flood preparedness by individuals • Findings: • No systematic approach to attain resilient buildings(DE, UK, F) • Sandbags limited use to SUCAs floods, logistic, practical and performance difficulties (UK) • Public not aware of self mitigation measures (DE, UK) • Some respondents had taken ad-hoc home made measures (DE, UK) • Actions: • Capacity building of architects and engineers (DE, UK, F) • See “empowering the public” • Include self mitigation measures in spatial planning regulations (DE, UK, F) • Financial incentives, e.g. through insurers, authorities (DE, UK, F) • Availability of good products, not just sandbags (DE, UK, F)

33. FLOOD-ERA Influence of selected context factorson ‘balancing SM and NSM’

34. Contents • Overview of CRUE’s first research funding initiative • Systematisation of structural and non-structural measures • Effectiveness and efficiency of non-structural measures • Risk perception and context factors for balancing measures • Conclusions on possible policy impacts

35. Conclusions The potential scope of flood risk reduction options by far exceeds the traditional flood protection approaches. A common systematisation could facilitate communication. New approaches allow for evaluating and comparing the effectiveness and efficiency of a number of NSM with SM using risk as a common currency. There is not clear tendency between SM and NSM. However NSM seem often to be less effective but more efficient. ‘Balancing SM and NSM’ in decision making (DM) is not just a matter of evaluation capabilities. Other context factors could even be more important. Challenges arise from further measures and evaluation criteria (e.g. sustainability, robustness).

36. References • EWASE (www.ewase.net) • Room for the River (www.iiama.upv.es/room for the river/home.html) • PRO_Floodplain (www.pro-floodplain.eu) • FloodRisk (www.flodrisk.info) • RISKCATCH (www.riskcatch.info) • SUCA (http://suca.wb.tu-harburg.de) University of Sheffield, University of Manchester, CEREVE, Ecole Nationale des Ponts et Chaussées, Hamburg University of Technology • FLOOD-ERA (www.flood-era.ioer.de) ihwb

37. Acknowledgement This presentation is based on contributions from the research projects funded under the 1st Call of the CRUE Funding Initiative on Flood Risk Management Research. Thank you for your Attention.