‘Reducing vulnerability of urban lowland areas’

Rutger de Graaf

Acknowledgements

The concept of vulnerability

• Why is it important: • Objective of society to become less vulnerable to

environmental variation such as variation of water resources and variation of water levels

• Future variation is uncertain

The concept of vulnerability

• A common definition of vulnerability:

‘sensitivity of a system for exposure to shocks, stresses and disturbances, or the degree to which a system is susceptible to adverse effects’ (Leurs, 2003; Turner et al., 2003; IPCC, 2001; Schiller et al, 2001)

• Disturbances or can be both exogenous or endogenous.(eg. A drought can be caused by low precipitation, bad water management or both)

The concept of vulnerability

• Possible responses towards environmental variation that reduce vulnerability: • Reduce (or control!) environmental variation

Building a threshold, example:• Reduce damage if this threshold is exceeded

Develop ability to cope with impacts• Recover quickly and effectively after damage has

occurred Develop ability to recover

• If future variation is uncertain and potential impacts are large Develop ability to adapt

Type Time orientation

Responsibility

Threshold Capacity

Damage

prevention

Past Clear

Coping Capacity

Damage

reduction

Instant Not clear

Recovery Capacity

Damage

reaction

Instant/

future

Not clear

Adaptive Capacity

Damage

anticipation

Future Undefined

The concept of vulnerability

Flood control

Flood control

Water

supply

Water

supply

Threshold Capacity

Higher dikes Increase river capacity

Increased reservoir capacity

More efficient supply infra

Coping Capacity

Improve risk perception

Emergency plan & warning

Backup supply facilities

Individual storage

Recovery Capacity

Disaster funds & Insurance

Recovery plans

Multi-source water supply

Disaster funds & Insurance

Adaptive Capacity

Flood proof & flexible urbanization

Small scale pilot projects

Flexible portfolio of sources

Small scale pilot projects

The concept of vulnerability

The concept of vulnerability

• Vulnerability of a system is difficult to assess because components of vulnerability are strongly interrelated.

• Example: Increased flood defense (threshold capacity) leads to increased urbanization and a decreased flood risk perception (coping capacity).

Dutch vulnerability lock in

Coping

Capacity

Adaptive

Capacity

Threshol

d

Capacity

Recovery

Capacity

Urbanization

Increased flood risk

Higher dikes

& pumpingcapacity

UrbanizationVulnerable delta

Land subsidenceIncreased vulnerability

Lock-in

Threshold capacity

Coping capacity

Recovery capacity

Adaptive capacity

Concluding remarks

• If we accept that we cannot completely control environmental variation, developing threshold capacity only will make us vulnerable for rarely occurring, high impact flood events and drought events

• 4 components of vulnerability framework may assist in developing more comprehensive strategies

• Governance mechanisms to successfully introduce the 4 capacities in everyday practice of citizens and professionals are still lacking

Questions

r.e.degraaf@tudelft.nl

Literature:• Water Science and

Technology, Vol 56 No 4, pp 165-173

• Natural Hazards, 2008• Urban Water in Japan,

Taylor& Francis Urban Water Series vol 11