Hssr02 kvk0905

HSRR02FLOODRISKASSESSMENTINUNEMBANKEDAREASINTHENETHERLANDS

September 2010 FLOODRESILIENCEGROUP

Kennis voor Klimaat Knowledge for Climate

SEPTEMBER 2010

FLOODRESILIENCEGROUP


William VeerbeekFLOOD RESILIENCE GROUP | WE Department | Unesco-IHEWestvest 7 | P.O. Box 3015 | 2601DA Delft | NetherlandsT: +31(0)15 2151 821 | M: +31(0)6 427 88 359w.veerbeek@fl oodresiliencegroup.orgwww.fl oodresiliencegroup.org




Assess potential fl ood hazard and impact for the unembanked areas in the • Rijnmond-Drechtsteden region;Include climate change scenarios;• Apply a high level of detail;• Include regional adaptation option: Closable but Open.•

RESEARCH OBJECTIVES

Flood impact Urban area

Flood extent & depth

Flow velocitiesFlood impact

Port area

Climate Change scenarios

Closable Open Rijnmond




Located along the Meuse & Merwede (Waal) rivers;• 30,000 housing units, 64,000 inhabitants;• Port of Rotterdam;• High level of diff erentiation (physical, functional, historical, etc.);• Unembanked area, often high level of elevation (sedimentation & man-made).•

RIJNMOND-DRECHTSTEDEN: CHARACTERISTICS

Veerbeek et al, 2010




1. FLOOD HAZARD

FLOODRISKASSESSMENTINUNEMBANKEDAREASINTHENETHERLANDS




Inundation depths derived from 1D-Hydraulic model HSRR03b • (Stijnen & Slootjes, 2010), for current, G+ 2050 and Veerman 2100 scenarios & Closable but Open;5x5m DEM resolution;• GIS extrapolation of observed water stages;• Flood velocities through existing hydraulic models and measurements;• Failure rate of Maeslant & Hartel storm surge barrier;• Range of return periods: 10, 50, 100, 1000, 2000, 4000, 10000 years.•

FLOOD MODEL: METHODOLOGY

Climate Change Rhine Discharge Meuse Discharge Sea level rise [m] Storm duration [h] Scenario at Lobith [m3/s] at Borgharen [m3/s]

Current Conditions (2010) 16,000 3,800 0 29KNMI’06 G+ (2050) 18,000 4,600 0.60 35VEERMAN (2100) 18,000 4,600 1.30 35

Lansen et al, 2010DEM of the Rijnmond-Drechtsteden area




10Return Period

10002000400010000

100

Many natural fl oodplains are fl ooded for low return periods (e.g. 10y)• Urban areas are generally fl ooded only during ‘extreme events’• Newer port areas (Rotterdam & Dordrecht) are relatively ‘safe’•

OBSERVED FLOOD EXTENT (CURRENT CONDITIONS)

Based on Huizinga et al, 2010




Within urban areas observed fl ood extent diff ers signifi cantly• Treshold eff ects and gradual fl ooding•

OBSERVED FLOOD EXTENT (CURRENT CONDITIONS)

10Return Period

10002000400010000

100

Noordereiland/Piekstraat Rotterdam• Inundation for low return periods• Main streets fl ooded during ‘extreme • events’





8000

9000

10000

11000

12000

13000

14000

15000

16000

17000

0 2000 4000 6000 8000 10000 12000

Return period (years)

Floo

ded

area

(ha)

2010205021002050_lockable/open2100_lockable/open

Flood extent for the range of return periods

Climate change scenarios increase fl ood extent signifi cantly;• Closable but Open option does not lead to reduction;• Failure rate Maeslant/Hartel storm surge barier is critical.•

OBSERVED FLOOD EXTENT




200Depth [cm]

0

Signifi cant variations in inundation depths also outside natural fl oodplains;• For medium return periods (e.g. 100y): Generally low inundation depths in highly • populated areas;Some exceptions (e.g. Noordereiland/Piekstraat area)•

OBSERVED INUNDATION DEPTHS

Noordereiland/Piekstraat Rotterdam• EP = 1/100, Current conditions• Signifi cant fl ood depths observable • within residential areas


Locally more than 1m of inundation




MAASSLUISSTADSHAVENS

VAN BRIENENOORDBRUG

STADSWERVEN

High fl ow velocities only at the Western end of the river mouth (North-Sea);• Flow velocities on quays expected to range between 0.1 and 0.25 m/s;• Further inland even lower (high hydraulic roughness due to built-up areas);• Climate change scenarios will not increase velocities signifi cantly;• Conclusion: Low probability of structural damages and casualties/injuries. •

FLOW VELOCITIES

Asselmans, 2010

Calculated fl ow velocities main channel: low fl ow conditions combined with a severe storm surge

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

12:00 00:00 12:00 00:00 12:00 00:00

time (hours)

flow

vel

ocity

(m/s

)




2. FLOOD IMPACT





Estimate DIRECT fl ood damages;• High level of detail: individual housing units, infrastructure and public space;• Derive damage composition;• Perform analysis on spatiotemporal distribution of damages;•

Refi nement from existing fl ood damage model used in UFM-Dordrecht • (Veerbeek et al, 2009);Introduction of specifi c housing characteristics through Google Streetview;• Adapt model to 5x5m cells;• Model is synthetic; damage curves developed icw building/insurance sector.•

(URBAN) FLOOD DAMAGE MODEL: METHODOLOGY

Kennis voor Klimaat Knowledg




Hardly any noticeable threshold eff ects;• Small trend change for G+ 2050 and Veerman 2100 at 1000-year return period;• EAD: Increase for G+ (2050) 75%, Veerman (2100) 147%• 100 fold increase: Current 1000-year level becomes 10-year level (Veerman 2100)•

0

25

50

75

100

125

150

175

10 100 1000 10000

return period [Y]

exp

ect

ed

Dam

ag

e [

m€

]

Current 2050 G+

2100 Veerman 2050 Closable but open

2100 Closable but open

(URBAN) FLOOD DAMAGE MODEL: AGGREGATE DAMAGES

y = 4E-08x5.8845

0

20

40

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100

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180

225 250 275 300 325 350 375 400 425 450

water stage [cm +NAP]

exp

ect

ed

Dam

ag

e [

m€

]

Expected aggregate fl ood damages for RPs

Expected aggregate fl ood damages for water stages




Cleaning & drying, 11%

Floor & w all, 11%

Doors & w indow4%

Kitchen, 8%

Installations, 19%

Contents Damage, 48%

Infrastructure/public space: currently 20% of EAD;• Climate change scenarios hardly change this ratio .• Housing: Damage to furnishing about 50%.•

0

10

20

30

40

50

60

10 50 100 1000 2000 4000 10000

return period [Y]

expec

ted D

amag

e [m

€]

Cleaning & drying Floor & wall Doors & windows

Kitchen Installations Contents Damage

Damage compostion (housing) for the Veerman 2100 scenario

(URBAN) FLOOD DAMAGE MODEL: DAMAGE COMPOSITION

What fl ood damage reduction level can be achieved with an ef-fective early warning strategy?




-500

500

1500

2500

-1900 1900-1920 1920-1940 1940-1960 1960-1980 1980-2000 2000+Construction period

# flo

oded

housi

ng u

nits

10 50 100

-500

500

1500

2500

-1900 1900-1920 1920-1940 1940-1960 1960-1980 1980-2000 2000+Construction period

# f

looded

housi

ng u

nits

10 50 100

0

1000

2000

3000

-1900 1900-1920 1920-1940 1940-1960 1960-1980 1980-2000 2000+

Construction period

# f

looded

housi

ng u

nits

10 50 100

Current Conditions

G+ Scenario 2050

Veerman Scenario 2100

Distribution of fl ooded buildings over the age of the building stock (10, 50, 100y);• Dramatic increase of fl ooded monumental buildings (e.g. Dordrecht)•

(URBAN) FLOOD DAMAGE MODEL: AGE BUILDING STOCK

Damage distribtuion over the age of the building stock

Is increasing fl ood risk a threat to our cultural heritage?




(URBAN) FLOOD DAMAGE MODEL: ABSOLUTE VS RELATIVE DMGS

Relative dmgs: expected dmg over the total building stock per municipality;• Substantial diff erences between municipalities: rate, behavior; absolute, relative;• Infl uence of climate change scenarios changes distribution;• Avg. EAD Rotterdam: € 4 (current) to € 29 (2100 Veerman);• Avg. EAD Bergambacht: € 614 (current) to € 660 (2100 Veerman).•

RotterdamDordrechtNederlekBergambacht0

5

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30

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40

45

50

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10 100 1000 10000

return period [mY]

exp

ect

ed

Dam

ag

e [

m€

]

Bergambacht Dordrecht Nederlek Rotterdam

0

5

10

15

20

25

30

35

40

45

10 50 100 1000 2000 4000 10000

return period [mY]

exp

ect

ed

Dam

ag

e [

k€

]

Rotterdam Dordrecht Nederlek Bergambacht

Expected damages for the Veerman 2100 scenario: absolute (left) and relative (right) Do these fi gures indicate possible responses (structural / non-struc-tural)?




(URBAN) FLOOD DAMAGE MODEL: DAMAGE HOTSPOTS

50% fl ood damages located in 15% of the damage clusters: highly concentrated;• Importance of individual clusters changes for higher return periods (threshold ef-• fects)




(PORT) FLOOD DAMAGE ASSESSMENT: METHODOLOGY

No ‘standard’ application of stage-damage curves possible;• Existing risk assessment framework is extremely complex;• Potentially high level of indirect tangible and intangible damages;•

Focus on:• Infrastructure, utility-lifeline (electricity, gas, etc.);• Assessment of additional fl ood risk i.r.t. existing risk profi le for chemical plants. •




Effect of flooding Probability of damage given a flooding event

Casualties Societal disruption

Environment Economical damage

Berthing facilities Washout due to water run-off Quay wall CorrosionJetties Failure of berthing functionTerminal Roads and terrain not accessibleTerrain Washout due to water run-off Roads and railwaysUnderground facilities Rupture of pipe linesElectricity Failure and damage of electricity and ICT

Communication Failure and damage of communication Cables Pipe linesGeneral facilities Washing away of loose standing objects

Lighting buildings Lighting failure Safety installations Safety onsite cannot be guaranteedVehicles Damage to buildings

Effect of flooding Probability of damage given a flooding event

Casualties Societal disruption

Environment Economical damage

Facilities Cable trays are on ground level => spills + release of toxic goods + interruption of processes. Instability of construction of installation, for instance distillation columns built on footings

Process installations Rupture / damage of (empty) pipelines Pipelines Corrosion of (salt) water in installations Cooling installation Power failure => uncontrollable processes

Storage of goods Rupture of (oil) tanks due to high water pressures

Oil LNG cooled storaged=> during power failure uncontrolled boil-off

LNG (Controlled) shut-down installations during flood threat

LPG Release toxic material from storage Toxic gasses: H2F Gas supply fo electricity / hinterland

interrupted Vegetable oil

Qualitative assessment of vulnerability: Liquid bulk

Qualitative assessment of vulnerability: General harbour facilities

(PORT) FLOOD DAMAGE ASSESSMENT: EXPERT SESSION

Expert judgment to develop a qualitative assessment of fl ood impact•




(PORT) FLOOD DAMAGE ASSESSMENT: CHEMICAL INSTALLATIONS

Main question: What is the additional risk of 1m of inundation?• BowTie model to assess the ‘chain of consequences’ during hazard exposure;• Use of scenarios: Assess consequences of 1m inundation;• Compare a worst case scenarios with and without fl ooding;•

Events and circumstances

Undesireable event

Failure trees, hazards

Additional scenarios flooding

flooding

Worst Case ScenarioNo Flooding

Worst Case ScenarioIncluding Flooding

Casualties None/Limited None/LimitedAffected persons (health effects)

1000(~10 health effects)

1000-2000(~100 health effects)

Economic damage 10-100m EUR (plant, down time, claims)

10-100m EUR (plant, down time, claims)

Environmental damage Minor Signifi cantCultural damage None None

BowTie-Model: Propagation of consequences Outcomes (example)




(PORT) FLOOD DAMAGE ASSESSMENT: OUTCOMES

Wet bulk and infrastructure are sensitive to fl ood risk: societal disruption:Electricity supply (business interruption);• Roads, tunnels and pipes: supply chain disruption;• ICT services.•

Casualties and health:Limited number of casualties;• Flood could increase health impacts: Flood water as a distributor;• Additional impact of fl ood risk is limited;• EP in the order of 1/1000,000.•

Pitfalls:Cumulative risk: multiple plants are fl ooded because of even terrain;• Risk chemical plants depends largely on weather conditions (e.g. wind).•




3. CONCLUSIONS





CONCLUSIONS

Current vulnerability is limited:High level of risk diff erentiation between areas;• Especially historical housing stock protected;• Yet, area is vulnerable to ‘extreme events’• Limited additional risk to Rotterdam port area. Yet, potential for societal disrup-• tion during ‘extreme event’

Climate change:Considerable increase of fl ood impact, especially in urban areas;• Shift in fl ood damages: historic areas (e.g. Dordrecht).•

Further study:Coupling local adaptation measures to diff erent risk profi les;• Assessment of structural/non structural measures (e.g. insurance);• Methodological improvement: damage curves (functional, typological, etc.)• Indirect damages assessment port area: ripple eff ects•




WATERVEILIGHEID BUITENDIJKS SYNTHESE

FLOOD RISK IN UNEMBANKED AREAS

SYNTHESIS

CONCLUSIONS

More information at: www.kennisvoorklimaat.org•

Hssr02 kvk0905

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