Integated Urban Flood Risk Management

Chris Zevenbergen, William Veerbeek – COST C22/UNESCO-IHE Srikantha Herath – UN University

Sheffield & Don

Hannover

Drechtsteden

Lidköping

MARE partnership

Contents

• What is at stake ?

• Options for the future

• Conclusions and recommendations

What is at stake ? (1)

• >75% flood damage in urban areas;

• Current policies (if any) are generally directed to reduce flood probabilities;

• Despite economic considerations decisions on flood risk management are driven by events;

• The protection level is not the result of an economic trade-off;

• Extreme events (e.g. overtopping) are not yet taken into account/systems are not designed for failure.

What is at stake ? (2)

• Floods are on the rise (damage: 5% increase annually)

• Number of big flood disasters are increasing

• Only 5 percent of new development ‘under way’ in the world’s expanding cities is planned (UN, 2007).

• Spatial distributions by and large ignore flood risk

Need for change

• Increasing vulnerability and uncertainty

• Increasing complexity (and dynamics)

Current practise:

- Large (collective) protection systems

- Local scale interventions & preparedness

- Mixed strategies ?

Towards action

Bringing ideas into action is about:– Risk perception and communication– Changing human behaviour– Learning from best practices and failure– Relationships

Natural cause

Human cause

CatastropheCrisis

extreme weather events

major (devastating)

flooding

climate change

Extreme event vs disaster

Natural cause

Human cause

CatastropheCrisis

extreme weather events

major (devastating)

flooding

climate change

Extreme event vs disaster

Disaster impacts are determined

by vulnerability that can be

understood, managed and reduced.

Urbanisation

Current paradigm:• buildings last forever and ‘site or urban

location is eternal’ • planning practices based upon static

conditions of climate and building stock.

New paradigm:• cities are dynamic complex systems:

autonomeous/planned adaptation• change and variability are characterized by

uncertainty

CC: uncertainty increases

• Variability increases:more extreme events• Future climate cannot be predicted on the basis

of past events: probability is dead!• No best solution• Opportunities for innovations• CC actual impacts vs ‘autonomous’ impacts (e.g.

city development) difficult to distinguish: impact of the first is likely much higher

• CC incentive to reform current practices

Coping with increasing complexity and uncertainty:

Cultivating/enhancing resilienceCultivating/enhancing resilience::• Utilising Utilising reversible, robust, adaptable and diverse responsesreversible, robust, adaptable and diverse responses

(structural some non-structural options in a portfolio)(structural some non-structural options in a portfolio)• Multi-sectoral (all parties with flood risk and spatial planning

responsibilities)/linking organizations and institutions across scales• Long-term perspective • Building capacityBuilding capacity in people and systems (hard and soft) in people and systems (hard and soft)• Promoting Promoting active learningactive learning through engagement through engagement• Learning by doing in demonstration projects• Seizing window of opportunity (e.g. renewal projects)• Identifying and supporting Identifying and supporting championschampions• …..

* COST C22: CAIWA conference 2007

synergies/short term benefits

Building resilience measures in Hamburg

Pilot Dordrecht (Netherlands)

To successfully manage future floods it requires:– an understanding of what responses could be

used/are appropiate (much technology already available).

– the political will and infrastructure to deliver on these ideas.

– engagement of the public

Conclusions & recommendations

• CC provides an opportunity to rethink and adopt new approaches

• Impact of extreme events can be managed• Focus on impact reduction requires strong

engagement of the public• Experimentation and learning• Need to catalyse action in cities around the

world through dissimination of knowledge, demonstration projects, from learning networks and high profile events.

• Flood Resilience Centre