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

State of Water workshop, 30 March 2012Henk Wolters, ETC/ICM - Deltares1

Flood vulnerability

Thomas Kjeldsen, Michael Hilden,

and many others

Henk Wolters

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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 2012Henk Wolters, ETC/ICM - Deltares

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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.


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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:


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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.


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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.


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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


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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


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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. 2011 (Climate Cost)

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Flood Event Management- early warning- evacuation- rescue- First Aid

Post-flood measures- relief- cleaning up- financial aid - reconstruction

Prevention:- spatial planning- flood control- preparedness- insurances- evacuation plans

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


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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


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Adaptation: Room for River


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Adaptation: Tipping points and adaptive management


0,35m0,5m 1,3m0,8m

current flood protection policy

Robust alternative strategy

FlexibleAlternative

step by stepStrategy

2120 2140 2160 2200

2040 2060 2075 2100

Time range

SLR

most negativeIPCC scenario

most positiveIPCC scenario

ATP

moment foraction

Current shipping practiceAlternative shipping strategy

0,35m0,5m 1,3m0,8m0,35m0,35m0,5m0,5m 1,3m1,3m0,8m0,8m

current flood protection policy

Robust alternative strategy

FlexibleAlternative

step by stepStrategy

2120 2140 2160 2200

2040 2060 2075 2100

Time range

2120 2140 2160 2200

2040 2060 2075 2100

Time range

SLR

most negativeIPCC scenario

most positiveIPCC scenario

ATPATP

moment foraction

Current shipping practiceAlternative shipping strategy

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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)


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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


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the end


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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


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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


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Special Report on Emissions Scenarios (SRES)

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• 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.

Documents

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