ecca2013-1-2_4_1-vandeven.pdf

7/27/2019 ECCA2013-1-2_4_1-vandeVen.pdf

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18 maart 2013

Climate vulnerability assessment for urban

area in the Netherlands

Frans van de Ven, Chris Zevenbergen, Leendert van BreeDeltares / TU Delft, UNESCO-IHE andNetherlands Environmental Assessment Agency


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Climate change and urban areas

Research objectives:

How vulnerable are Dutch villages and cities for CC?

How to reduce this vulnerability by adaptationmeasures? When to implement these? Who?

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4.18%

25.82%

31.85%

28.32%

9.83%

0 1 2 3 4

Conclusions (1)

Vulnerability

Most urban areas in NL are vulnerable forflooding, drought and heat stress

Vulnerability is not only result of exposure;

also damage sensitivity (susceptibility) and

adaptability Only relativevulnerability per theme was assessable

Vulnerability varies largely per theme, region and town

section No relation found between vulnerability and urban

typology

Legend

Exposure

Aggregate Them

0

1

2

3

40 10 20 30 405

Kilomet

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5/23

Conclusions (2)

Adaptation

Through synergy with urban reconstruction 88 % of oururban areas could be climate resilient by 2060

Many low-cost, low-regret adaptation options. Low-cost

climate adaption seems feasible!

Adaptation measures depend on local conditions andpreferences

Effectiveness of measures is location-specific and hard

to quantify; research is needed! Climate adaptation is to be part of urban development

policy at all levels. Legislation is to be considered

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CC and urban areas in NL

Climate change leads to more exposure of urban areas

Sea level rise

More and more heavy rainfall More sever droughts

River flood peaks

Higher temperatures, more evaporation / water demand

Dutch cities are vulnerable because:

Site conditions (low, no gradient, soft soil)

Build centuries ago, with design criteria used in these days

Reconstruction only once per 50 100 year

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CC vulnerability of the urban system

Climate change

Urban Governance

Urbandevelopment

Hazard

Exposure

Sensitivity

Vulnerability

Urban

climate

Climate Governance

Adaptivecapacity

Adaptationmeasures

Mitigation

KvK voorstel Climate Proof Cities, 2009

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Vulnerability

Vulnerability is result of:

Exposure - frequency and degree of

Damage sensitivity (susceptibility)

Adaptability

Exposure: Indicative assessment, using data mining

Damage sensitivity

Poorly knownAdaptability

Aging of buildings and infrastructure indicative (?)

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Themes investigated

Coastal and fluvial flooding

Pluvial and groundwater flooding

Drought

Heat stress

For municipalities > 25.000 inhabitants

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Hazard

Exposure

Damage

Victims

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Hazards from: Sea Rivers, lakes, main canals

Secundary drainage system

Exposure and susceptibility Depth, duration and size of inundations

increase

30% of housing areas exposed Most floodprone houses are post WWII; Cultural heritage flood risk free Victims and direct economic damage are

assessed; indirect damage hardly known

Flood risk Exposure does not increase . . but hazard and damage sensitivity

does!

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Pluvial flooding

Flow accumulations for Delft

Predicted runoff distributions

for a 54mm precipitation eventfor the Rotterdam region

0.0% 5.0% 10.0

%

15.0

%

20.0

%

25.0

%

30.0

%

Zwolle

Maastricht

Leiden

Dordrecht

Zoetermeer

Amersfoort

Enschede

Apeldoorn

Breda

Arnhem

Haarlem

Nijmegen

Groningen

Tilburg

Almere

Eindhoven

Utrecht

's-Gravenhage

Rotterdam

Amsterdam

ratio buildings ratio infra

% flood - affected

buildingsand infrastructure

for 77 mm storm


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Pluvial flooding

Hazard from

More intensive rain storms

Exposure and susceptibility

NL is flat; no flash floods and limitedinundation depths

Low-lying urban areas at risk

Mostly small damage incidents (e.g.

flooded basement, flooded road) No relation with urban typology, except in

center zones.

Adaptation options

Increase retention and storage capacity, inparticular in low areas.

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Groundwater flooding

0 2.500 5.0001.250m

Present Situation;

Vulnerability to groundwater nuisance

drainage dependent

intermediatedrainage independent

0 2.500 5.0001.250m

KNMI'06 W+ scenario;

Vulnerability to groundwater nuisance

drainage dependent

intermediatedrainage independent

Indicative change in drainage dependency of urban areas(above: current situation; below: situation in the W+ scenario)

100 000

200 000

300 000

400 000

500 000

600 000

700 000

before

1800

from

180

0to

1899

from

190

0to

1919

from

192

0to

1939

from

194

0to

1959

from

196

0to

1969

from

197

0to

1979

from

198

0to

1989

from

199

0to

1994

from

1995to

1999

late

rthe

n200

0

Building period

Amountofbuild

ings

intermediary drainage dependent drainage independent

age and vulnerability of buildings

to groundwater nuisance


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Vulnerability to groundwater nuisancevulnerable

not vulnerable0 30.000 60.00015.000

Meters

Hazards from: Increase in rainfall and river discharges


Groundwater flooding occurs across NL(high - low, sand clay peat soils) Lowlands with their high groundwater

table and subsurface drainage system -and parks are the most vulnerable

More urban development in lowlands afterWW II

Land subsidence aggravates the problem.

Adaptation options

Plenty no-regret options available.

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Drought

Vulnerability to drought

not

substantial

strong0 30.000 60.00015.000

Meters

Hazard from Less rainfall in summer


Low grw level => low soil moisture &enhanced land subsidence Damage to wooden pile foundations

1/3 of pre-60 buildings ! Tree roots adapt to gradual increase of

drought Increased impact of salinization and

water temperature on water quality

Risk

Hard to quantify because of lack of data Damage can increase substantially.

Adaptation options Water supply required!

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Heat stress

Hazard from Temperature increase + UHI

Exposure ans susceptibility

Urban Heat Island effects can increaseexponentially with urbanisation Urban land use dependent. Industrial zones

and business districts perform poorly. Blue and green buffer the UHI effect

Elderly are particularly vulnenerable Air conditioning becomes the standard;

fossile energy consumption will increase Outdoor activities less attractive

Risk Related to density of urban fabric. Susceptibility not yet quantified.

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4.18%

25.82%

31.85%

28.32%

9.83%

0 1 2 3 4

Legend

Exposure

Aggregate Themes

0

1

2

3

40 10 20 30 405

Kilometers

Vulnerability

Total risk due to: Coastal and fluvial flooding Pluvial and groundwater flooding Drought Heat stress

In- addable

Result: Urban areas on higher ground limited

effect No relation to urban typology All cities have their hotspots

Young cities relatively vulnearable,because of their low adaptability

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Vulnerability

Taking adaptability into account:

40%

17%

19%

18%

6%

0 1 2 3 4

61%

11%

13%

11%

4%

0 1 2 3 4

spatial distribution of the Expected End of Lifespan

2010

2020


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Adaptive capacity

Urban areas transform each 50 100 years, on average

37% of our urban areas is at its end of economical life span;

these areas will need redevelopment in the next 10-20 years 88% of our urban areas could be climate resilient by 2060, if

synergy with this redevelopment is realised.

So: Adaptive capacity is large

Start now, not to miss any opportunities!


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Adaptation measures

Adaptability Many measures are no-regret or low-regret

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In conclusion

Adaptive capacity is large (2010-2060)

Many low-regret/low-cost measures available

Adaptation partly by public, partly by private parties

So:

Costs of adaptation are limited!

Well miss opportunities if we dont start now!

For all details see: Van de Ven, F, E van Nieuwkerk, K. Stone et al ( 2010)Building the Netherlands Climate Proof: urban areas. Report 1201082-000VEB-0003Deltares and Unesco-IHE, Delft/Utrecht

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