Dr. ir. Frans H.M. van de VenTU Delft / Deltares

Water robust urban development

Contents

• “Houston, we have a problem…”• Scope• Three-steps approach• Who is to take action• When to select measures• Conclusions

Our delta shows ongoing urbanization

200519701900

in particular in the lowest parts…

> 4 m - MSL

2 to 4 m - MSL

0 to 2 m - MSL

0 to 5 m+MSL

5 to 10 m+MSL

> 10 m+MSL

Rotterdam

Amsterdam

while the landsubsides,the sea level rises…

and climate is changing.Climate scenario’s (KNMI, 2006)

+10% +27% +5% +13% daily rainfall (T=10 yr)

+15% +7% +8% +3% evapotranspiration

-19% +6% -10% +3% average precipitation

Summer

+14% +7% +7% +4% average precipitation

Winter

NoYesYesNoChanging West circulation

W+ W G+ G 2050

Our responses

• [Reduce climate change]• [Improve predictions]• Strengthen our protection• Adapt our living environment• …

Water robust cities

Water robust cities (WRC):Urban areas (re)developed in such a way, that they are able to cope with a more extreme - water surplus or - shortage of water and - heat

Scope of WRC

• All water stresses: Flooding, drought & heat• New developments and existing urban areas• Buildings and public space• Technology, process, legislation and practiceTo identify appropriate measures, taking into

account– Types of water stress …– Types of vulnerability …

Measures we could take

> 100 measures identified…..• Collective ‘soft’ measures

e.g. contingency plans, building legislation

• Collective ‘hard’ measurese.g. dikes, drainage systems

• Individual ‘soft’ measurese.g. increasing water risk consciousness, insurances

• Individual ‘hard’ measurese.g. building without crawl space, wet or dry proofing

Our problem: how to select?

Our solution:

Three-step approach • Step 1: Completing a vulnerability-analysis• Step 2: Strategy to reduce vulnerability• Step 3: Selecting

appropriate measures

1. Vulnerability-analysis

Type of water stress

subsoil

network

occupation

Analysis of the subsoil / soil / water / urban design systemunder the influence of climate change

Based on the 3-layer approach to spatial planning

2. Strategy to reduce vulnerability

Four capacities to reduce vulnerability1:

• Damage prevention = threshold capacity• Damage reduction = coping capacity• Damage reaction = recovery capacity• Damage anticipation = adaptive capacity

1 Graaf, R. de, N. van de Giesen and F. van de Ven, 2007, Alternative water management options to reduce vulnerability for climate change in the Netherlands, Natural Hazards nov.

3. Selecting appropriate measures

Selection depends on:

• Results vulnerability analysis• Strategy to reduce this vulnerability• Available ‘hard’ and ‘soft’ measures

3. WRD measures selection

3. Recovery capacityExtra pumping capacityCleaning & drying capacityWater supplying capacity in extremely dry periods

Et cetera

4. Adaptive capacityTemporary houses & buildingsAdaptive management Water-based spatial planningRegular updates water & spacepolicies

2. Coping capacityMajor drainage sytem; adapted streetprofileWet proofingWarm grass instead cold grasses

Et cetera

1. Threshold capacityWaterrobust infrastructureEnlarged seasonal storagecapacityHigh floor level vs street levelFloating housing

Et cetera

Measures to strengthen …

3. Selecting appropriate measures

Selection depends on:

• Results vulnerability analysis• Strategy to reduce this vulnerability• Available ‘hard’ and ‘soft’ measures• The stakeholders (!!)

Who are the stakeholders?

Public• State • Province• Municipality• Water board

Private• Owner-occupier• Real estate developers

• Housing associations• Waterworks

• Electricity companies• Telecom companies

• Insurance companies• Mortgage banks

Note: Different parties involved in each phase of a (re)development process !

When to select measures

Depends on the phase of development: • Planning • Design• Building• Maintenance

When to select ?= when to apply this three-step approach

1. Spatial planning phase : Select strategy and principal WRD solutions in spat ial plans

2. Spatial developmenta. Initiative: embracing the idea of a WRDb. Draft designs: select water robust measures (spatial water strategy)

3. Feasibility study : market analysis

4. Design, planning, preparation, costs, permits .a. Developing the plan

1. Contracts2. Commitment

b. Urban design: final selection of measures

5. Building processa. Engineering/preparation technical design of selected measuresb. Building site preparation: realization of water robust solutionsc. Constructiond. Completion

6. Maintenancea. Property-, asset- en portfolio management Select water robust maintenance measuresb. Keep up operational rescue capacity, …

Spatial planning phase

Planning & design phase

- At transfer- Corrective measures

In conclusion

• No best, no most robust solution; • Selection of appropriate measures is a

negotiation process– Vulnerability analysis– Strategy to reduce vulnerability

Making water robust cities is challenge,but it is

feasible and affordable

Steering committee:

-consortium thanks

+ Advisory board WRC:

More informationMore information:

www.bouwrijp.nlwww.wrm.tudelft.nl

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