New Approaches for Flood Risk Management in the Netherlands 4th International Symposium on Flood Defence Toronto, Canada 08/05/2008

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Transcript New Approaches for Flood Risk Management in the Netherlands 4th International Symposium on Flood Defence Toronto, Canada 08/05/2008

Slide 1

New Approaches for Flood Risk
Management in the Netherlands
4th International Symposium on Flood Defence
Toronto, Canada

08/05/2008


Slide 2

Outline
Background on Flood Safety in the Netherlands
Policy Developments
Causes
Developments
Process

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Slide 3

Flood protection is crucial for the Netherlands


60% of the country is threatened by
floods



70% of the GNP (600 billion US$) is
threatened by floods



Large cities like Amsterdam and
Rotterdam are below sea level

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Slide 4

Defence system developed after disasters
Afsluitdijk (1932)

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Slide 5

The 1953 storm surge disaster

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Slide 6

The 1953 storm surge disaster
The 1953 storm surge disaster (1800 casualties, 1800
sq. kms flooded) led to the Deltaplan, including:
Closure of estuaries
Safety standards on
an economic basis
National dike
improvement scheme

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Slide 7

Present flood defence system
Dunes

Levees and
space for
rivers

Dams and barriers

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Slide 8

The Flood Protection Act (1996)
The Flood protection act dictates:

The safety standards per ‘dike ring’
area (freq. of exceeding of design
water level)
The responsibilities of the parties
involved
A 5-yearly safety assessment of all
primary flood defences

Safety assessment & Design of flood is
prescribed in guidelines

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Slide 9

Causes for New Policy
2005: Policy Evaluation
Risk of flooding has grown
Standards are not up-to-date
Safety Standards are never fully
complied
Safety Chain / Emergency
Management Cycle is not used

Attention for Climate Change,
urge to be prepared for future
New Orleans was a eyeopener
Development of Risk-based
techniques (FLORIS project)

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Slide 10

Present Discussion about Flooding Risk in the
NL
2010
2005 (est.)
1970
1950

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Slide 11

Process
“From the outside inwards”
In 2006 several meetings were organized
Technical meetings about prevention, spatial measures, safety chain and
cost-benefit analysis
“Dike-Ring Meetings”, with cross section of stakeholders (not only water
professionals)

Gathering of ideas for new policy
In 2007, the most promising ideas were further investigated
Spring 2008: concept of new policy is discussed with
stakeholders
Fall 2008: policy document

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Slide 12

Main Elements in Future Policy
General:
Risk Based Policy, meaning
Multi-layer safety principle
Standards based on risk assessment

Robust, future based
Improvements for prevention system
Robustness in the 5-yearly safety assessment, take into account
reinforcement period (20 year)
Robustness in designing new flood defences
Step forward to safety standards in terms of probability of
flooding
Reconsider safety standards based on CBA and acceptability of
casualties (Individual Risk, Group Risk)

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Slide 13

Main Elements in Future Policy (2)
Overflow-proof dikes or “superlevees”?
Compartmentalization of larger dike-rings?
Improvements for “Reducing Consequences”
Incorporate flood risk in “Water Test”
Framework for climate-proof spatial planning
Protect Vital functions (electricity, water supply etc.)
note: still under debate…
Emergency Management
Task Force Management of Flooding (TMO), improve emergency
organization, exercise “Waterproof” end of 2008
Keep emergency management organization
Raise awareness of public and politicians for flood risk management

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Slide 14

Challenges
Make probability of flooding work in practice: Guidelines for
assessment and design based on probability, applicable for
waterboards
Discussion about height of safety standards
Requires lot of data (FLORIS, cost estimates, future scenario’s
Combining economical, personal and group risk
Differentation of safety standards

Communicate change from old to new safety standards
Role of Water in Spatial planning

Balance between preventive and other measures

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Slide 15

Timeline
2008 Flood Safety policy document
fundamental changes
components of new policy
Course CBA, financial impact, paper 105, session D

2009-2013 Implementation
New standards based on CBA, estimates of casualties, societal discussion
Results of VNK/FLORIS
Instrument for safety assessment
Adjustment Flood Protection Act
Synchronisation with EU Guideline for Flood Risk Management

2013 Safety assessment according to new policy

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Slide 16

Questions ??

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