1. Thomas Kjeldsen, Michael Hilden, and many others Henk Wolters
Flood vulnerability
Thomas Kjeldsen, Michael Hilden,
and many others
Henk Wolters
State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

2. Contents What are the trends visible in the recent past
Uncertainties and scenarios
Projections of flood hazards and risks
Flood risk management
Key messages
State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

3. Glossary (following UNISDR) risk = hazard * negative consequences
hazard is the combination of magnitude of an event and its probability
negative consequences depend on exposure (what is there) and vulnerability (how susceptible to damage is what is there)
Flood hazard is determined by basic hydrological parameters and characteristics of the catchment
Exposure grows with economy, investments, inhabitants etc.
State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

4. What are the visible trends (1)
Land use change: from forests and wetlands to agriculture
except specific cases, there is no evidence that this type of land use change has affected flood hazards
Land use change: from agriculture to urbanised areas
with profound effect on both hazard and consequences, see case Athens in the report
Have flood hazards changed? The picture varies:
State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

5. What are the visible trends (2)
7-day maximum trends across Europe, 1962 – 2004 Stahl et al. 2011). Blue circles denote positive trends,
red circles negative, with trend magnitude expressed in standardized units.
State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

6. What are the visible trends (3)
Total flood damages have increased over the past decades.
This is attributed mainly to socio-economic development, rather than climate change. Improved data collection and better reporting may have contributed too.
State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

7. Scenarios
The aim of scenarios is to facilitate decisions that are robust under a wide range of possible futures. Scenarios are used in flood risk management to better understand the consequences of these uncertainties.
Comprehensive, integrated scenarios include:
socio-economic development (SRES)
greenhouse gas emissions (SRES)
global and regional climate models
a.o. rainfall, temperature, distributions
hydrological processes
land cover and land use
economic activities
measures and responses
State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

8. Projections of flood hazards and risks
It is widely accepted that heavy precipitation events will become more frequent and/or intense under global warming
Flood hazard increases have been predicted in several basins, and may happen in short time spans
Global warming is likely to reduce flood hazard where snowmelt floods dominate
In many parts of Europe there is much uncertainty
In the short term, natural hydrological variability obscures climate change
State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

9. Projected annual flood damage
Relative change in expected annual flood damage due to climate change a) 2000s
b)2020s; c) 2050s; d) 2080s. Scenario A1B. Based on Floerke et al (Climate Cost)

10. Flood risk management (1)
Flood risk management entails:
careful analysis of flood hazards & their causes
assessment of the magnitudes of risks
systematic planning to reduce risks
adaptation in the face of possible change.
Incorporating elements of
Prevention, Flood Event
Management and Recovery
State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

11. Flood risk management (2)
Some special issues in FRM:
Urban flood management:
there is a general need to make urban areas more resilient to flooding. Urban water management plans need to be developed.
Participatory management:
Involvement is encouraged. Can help to build awareness, trust and motivation for taking actions. Insurance is an important tool, implemented very diversely across EU.
Developing governance:
Transition from top-down to participatory management, including relevant actors, and including uncertainties, e.g. by the tipping points/adaptive management approach
State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

12. Flood risk management (3)
Adaptation: Room for River
State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

13. Flood risk management (4)
Adaptation: Tipping points and adaptive management
State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

14. Key messages (1)
Looking back: flood hazards seem to have increased in northern Europe, western UK and western Scandinavia, to have decreased Spain, while in central Europe the pattern is very mixed.
Looking back: damage caused by floods has increased. Primary cause is economic development and population growth, better reporting may also have contributed.
Looking forward to hazards: global warming is likely to reduce flood hazard where snowmelt floods dominate. In other regions there is much uncertainty. Increases in extremes are calculated for several river basins; they may occur in a relatively short time span, due to variability and non-linear system behaviour.
Looking forward to damage: projected changes point towards an increase in flood damage from €5,5 billion in 2000 to €98 billion by 2080 (ClimWatAdapt)
State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

15. Key messages (2)
Flood risk management is developing according to the EU Floods Directive. The report asks special attention for:
urban flood management
stakeholder participation, including insurance
governance, including adaptive management
State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

16. the end State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

17. Glossary (extended)
exposure: people, property, systems or other elements present in hazard zones that are subject to potential losses
vulnerability: characteristics and circumstances of a community, system or asset that make it susceptible to a hazard
State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

18. Types of floods
Floods are a natural phenomenon, becoming a problem when interfering with human land use and infrastructure
Types of floods
coastal floods
fluvial floods
pluvial floods
flash floods
floods caused by dam failure
State of Water workshop, 30 March 2012
Henk Wolters, ETC/ICM - Deltares

19. Special Report on Emissions Scenarios (SRES)

20. Prevention: preventing damage caused by floods by avoiding construction of houses and industries in present and future flood-prone areas; by adapting future developments to the risk of flooding; and by promoting appropriate land-use, agricultural and forestry practices;
Protection: taking measures, both structural and non-structural, to reduce the likelihood of floods and/or the impact of floods in a specific location;
Preparedness: informing the population about flood risks and what to do in the event of a flood;
Emergency response: developing emergency response plans in the case of a flood;
Recovery and lessons learned: returning to normal conditions as soon as possible and mitigating both the social and economic impacts on the affected population.