ESPACE INTERREG III B De Smet Michel Stefaan Nollet Wim Dauwe District Sea-Scheldt

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ESPACE INTERREG III B

De Smet MichelStefaan NolletWim Dauwe

District Sea-Scheldt

vrijdag 21 april 2023

Updating of the SIGMAPLAN

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1. Introduction and situation1. Introduction and situation

2. History of the Sigmaplan

3. Updating is necessary

4. How to do it ? New approaches

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Estuary of the Scheldt

355 km river length21.863 km2

10 500 000 people

Sea Scheldt

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Gemiddelde tijkrommen te Antwerpen

0

1

2

3

4

5

6

7

-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8

tijd in uur

m T

.A.W

.

springtij

doodtij

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gemiddeld HW en LW

-1

0

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2

3

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5

6

7

0 50 100 150

afstand in km

doodtij LW

doodtij HW

springtij LW

springtij HW

GentVlissingen Hansweert Antwerpen Dendermonde

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- St Elisabethflood in 1404- St Elisabetflood in 1421- St Felixflood in 1530- All Saintsflood in 1570

Some flood disasters

- Februari 1953

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1836 slachtoffers

Disaster of 1953

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- St Elisabeth flood 1404- St Elisabeth flood 1421- St Felix flood 1530- All Saints 1570- February 1953- January 1976

Some flood disasters

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Flood disaster of 1976

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The SIGMAPLAN of 1977

Decision :Ministerial decision of Feb 18, 1977 implementation of the SIGMAPLAN

Target :Protection of the basin of the Sea Scheldt against a storm surge orinating from the North Sea with a probability of occurrence of 1% in a century (= 1 per 10.000 years) 8.97 m T.A.W. in Antwerp

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GENT

BOOM

LIERTEMSE

ZEMST

DUFFEL

ITEGEM

SCHELLE

LOKEREN

VIERSEL

MECHELEN

WETTEREN

OOSTERLO

WERCHTER

ANTWERPEN

VILVOORDE

ZANDVLIET

DENDERMONDE

GROBBENDONK


a) reinforce all river embankments (dikes)b) construction of flood control areasc) construction of a storm surge barrier ds Antwerp

zone 1 : 11,00 m TAW

zone 2 : 8,35 m TAW

zone 3 : 8,00 m TAW

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target levels of embankments

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6

7

8

9

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0 50 100 150

distance in km

m T

.A.W

.

GentVlissingen Hansweert Antwerpen Dendermonde


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GENT

BOOM

LIERTEMSE

ZEMST

DUFFEL

ITEGEM

SCHELLE

LOKEREN

VIERSEL

MECHELEN

WETTEREN

OOSTERLO

WERCHTER

ANTWERPEN

VILVOORDE

ZANDVLIET

DENDERMONDE

GROBBENDONK



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ScheldtCIA

1

2

3

4

ringdike weir

1

2

3

4


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GENT

BOOM

LIERTEMSE

ZEMST

DUFFEL

ITEGEM

SCHELLE

LOKEREN

VIERSEL

MECHELEN

WETTEREN

OOSTERLO

WERCHTER

ANTWERPEN

VILVOORDE

ZANDVLIET

DENDERMONDE

GROBBENDONK


KBR


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90 m 90 m

54 m 54 m 54 m

lift gates

sector gates

125 m


2003 : 1.000.000.000 EUR

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Storm Surge barrier 1977

In 1982 a benefit cost analysis was performed• without taking into account sea level rise• taking into account a construction cost of

1.000.000.000 Eur (price level 2003)

Results:discounted costs = 30 to 40 times disc. benefitsno pay back during project life (100 year)

construction of barrier postponed indefenitely

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Realized : - 80 % of all planned embankment works- 12 of 13 planned CIA’s are operational- CIA Kruibeke - Bazel - Rupelmonde under construction

Result :- 1 / 70 year (7,83 m TAW) : situatie now- 1 / 350 year (8,24 m TAW) : when KBR operational

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Updating is necessary

1. Changing boundary conditions - stronger tidal cycles - climatic change

2. New vision on design criteria - design water levels benefit cost analisis

3. New vision on water management - sustainable development is the central theme - transnational estuary management (NL-FL)

Zeeschelde te Antwerpen - Loodsgebouw : langjarige tij-evolutie (algemeen)

-100

0

100

200

300

400

500

600

1880

1890

1900

1910

1920

1930

1940

1950

1960

1970

1980

1990

2000

tijd (in jaren)

wat

erst

and

(in

cm

TAW

)

jaargemiddeld hoogwater jaargemiddeld laagwater jaargemiddelde halftij-waarde

jaargemiddelde tij-amplitude Polynoom (jaargemiddeld hoogwater) Polynoom (jaargemiddelde tij-amplitude)

Polynoom (jaargemiddelde halftij-waarde) Polynoom (jaargemiddeld laagwater)

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We are confronted with :

- stronger tides (GHW en GLW)- rising sea level- increasing frequency of storms- increasing peak discharges of run-off

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Antwerpen : overschrijdingslijn hoogwaterstanden

3697223

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7

8

9

10

1 10 100 1,000 10,000

Terugkeerperiode (jaar)

Data 61-75 (Theuns) Data 71-90 (Claessens) Data 71-97 (Taverniers) Prognose (2050) Prognose (2100)


60 cm

1 / 70 year (7,83 m TAW) : situation now1 / 350 year (8,24 m TAW) : with CFA KBR

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In 5 steps towards an updated Sigmaplan

• Step 1: Define the building blocks

• Step 2: Build simulation models

• Step 3: Top down approach: defining the type of solution

• Step 4: Bottom up approach: refining the selected type of solution

• Step 5: Decision of the Flemisch government

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Raising the dikes

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Build a barrier ds/ Antwerp

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or small barriers at Mechelen and Lier…

#Y

#Y

#Y

#Y

#Y

#Y

#Y

#Y

%[

%[

ANTW ERPEN

LOKEREN

GENT

ZEMST

MECHELEN

ITEGEM

GROBBENDONK

WERCHTER

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Controlled Inundation Areas (CIA)

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180 potential CIA’s (15 000 ha) have been identified

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Simulation of inundations

• A 1D hydrodynamal model with branches in the Western Scheldt– Simulation of inundation areas by means of paralel branches– Include effect of wind setup on the Westerscheldt– Generate upper discharges by means of hydrological models

• Apply GIS for estimating flood damages

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Modelled area

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Complete model

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Modeling of flood prone areas

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Boundary conditions / Breaches

• Composite boundary conditions for eleven return periods: T 1, 2, 5, ...1000, 2500, 4000, 10000

• Seaward boundary: waterlevel, wind• Upstream boundary: discharges

Development of breaches taken into account:• at overflow• when waterlevel enters freeboard

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Calculate inundation damage

• Damage and victims are calculated using damage functions developed at WLH (Vanneuville), combined with the inundation maps and land use maps in GIS

• An area of 1630 km² is covered

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Model for estimating construction costs and operation & maintenance costs

dikes, quay walls, barriers, CIA ’s

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Large storm surge barrie

• Antwerp barrier: alternative design after existing construction along Nieuwe Waterweg (Netherlands)

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Small storm surge barriers on Rupel

• Mechelen en Lier: scaling the Beernem barrier (B)• Niel (Rupel): scaling the Hartel barrier (NL)

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Construction period

Estimated on basis of :• available budgets for Sigma : 50 million EUR / year

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Model for Benefit Cost Analysis

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Benefit cost analysis principle

• The zero reference scheme is the completed 1977 Sigma plan without the storm surge barrier

• All possible alternative schemes are compared to the zero reference scheme. – storm surge barrier– Dike heightening : e.g. T2500 (in 2050)– space for river: CIA 1800 ha (T1000)

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What’s compared

Costs Benefits additional effects

Investments

Operation and maint.

NOT

•expropriation grounds

•Compensations

•taxes

Avoided costs in Flanders

Avoided costs in NL

Avoided risk in Flanders

Avoided risk in NL

Victims

Navigation

Visual disturbance

Costs for agriculture in CIA

Cost for loss of loss of acreage under cultivation

Benefits for nature

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Discounted costs and benefits

Costs and benefits are changing in timeMainenance (small and large)avoided risks change (sea level rise, economic growth)construction time and usefull life of projects differs

Approach all construction works start in 2010Cost and benefits calculated up to 2100Residual value after 2100 Discounting : 3, 4 , 7 %

Costs and benefits discounted to 2004 Net present value of the project Pay back time

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Results: buying guide

List

Costs

Benefits

Other effects Compare

Net Present Value of the project

Pay Back Time

Not :

• how to finance, who pays damage in case of inundation

• no effects analysis for sectors or businesses

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Define a number of alternative schemes

Using protection level 2050 as a design criterion• Schemes with storm surge barrier• Schemes with dike heightening (T2500 en T4000)• Schemes with CIA’s (T1000, T2500, T4000)

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Perform the hydraulic design

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Determine the necessary CIA’s out of 15000 ha identified potential CIA’s

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1800 ha (T1000)

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2330 ha (T2500)

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2800 ha (T4000)

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6900 ha (T4000+Q)

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7700 ha (T4000+ontp+q)

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9250 ha (T4000+ontp+q+res)

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Results of top down approach

Costs Benefitstill 2100

Other PBT

year

Storm surge barrier Antwerp

387 727 - 1 41

Dikes T2500 240 691 - 27

CIA (1800 ha) 140 648 -18 17

CIA with CRT (1800 ha) 151 648 33 14

milj Euro, discounted to 2004, 4% disc.

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Combining safety - nature

input from the ecological rehabilitation plan and ecosystem model for the Scheldt estuary !

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ScheldtFCAwith

CRT

ringdike weir

1

2

3

4

Combining safety - nature

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SIGMAPLAN : FLOODSCAPE & FRaME

Prosperpolder

Durme

Antwerp

KBR

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Risk map anno 2100: damage centers

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Bottom up methodology

• five damage areas (5)• start from zero reference scheme• look for optimal incremental scheme in zone 1• decide on : PBT, NPV, remaining risks• zone 2: starting from zero reference scheme + best solution zone

1• etc

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Methodology: 5 optimization areas

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Zone 1

Or

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Zone 2

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KBA Zone 2: heightening of dikes ?

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Zone 4

Kalkense meersen

WijmeersRot en Bastenakkers

or

raising dikes

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Zone 3 (Dijle, omgeving Mechelen)

OF

SVK Niel

Battenbroek

HeindonkOude Dijlearm

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Area 5-1

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Final result

Costs Benefitstill 2100

Other PBTyear

SVK Oosterweel 387 727 - 1 41

Dikes T2500 240 691 - 27

CIA’s (1800 ha) 140 648 -18 17

CIA as RFA (1800 ha) 151 648 33 14

Optimal sigmaplan (With CIA1325 +656 ha)

143 752 -11 15

milj Euro, discounted to 2004 with 4% disc.

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Sensitivity analysis

The optimal scheme will be submitted to various sensitivity tests using BCA method:

• sea level rise higher/lower/null• discount rate higher• economic growth higher/lower• changing breach modeling• changing boundary conditions• sedimentation in CIA’s• level of overflow levees in the CIA’s

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Influence of sea level rise on Sigma2

Zeespiegelstijging 2100 0 cm 30 cm 60 cm 90 cm 120 cm

Geactualiseerde totale kosten 131,71 131,71 131,71 131,71 131,71

Geactualiseerde veiligheidsbaat tot 2100

138,13 437,44 736,75 1036,05 1335,36

Andere effecten tot 2100

landbouw -12,37 -12,37 -12,37 -12,37 -12,37

zicht omwonenden -5,18 -5,18 -5,18 -5,18 -5,18

recreatie 8,78 8,78 8,78 8,78 8,78

Totale netto geactualiseerde baten tot 2100

-2,35 296,96 596,26 895,57 1194,88

Terugverdientijd (jaar) 92 24 16 12 10

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• Step 5: Decision of the Flemisch government (01-07-2005?)

Documents

ESPACE INTERREG III B De Smet Michel Stefaan Nollet Wim Dauwe District Sea-Scheldt