presentatie 27-02-2003

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Updating of the SIGMAPLAN
ESPACE INTERREG III B De Smet Michel Stefaan
Nollet Wim Dauwe District Sea-Scheldt vrijdag
25 maart 2016
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Updating of the SIGMAPLAN
1. 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 length 21.863 km2 10 500 000 people
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Updating of the SIGMAPLAN
1. Introduction and situation 2. History of the
Sigmaplan 3. Updating is necessary 4. How to do
it ? New approaches
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Some flood disasters
- St Elisabethflood in 1404 - St Elisabetflood
in 1421 - St Felixflood in 1530 - All
Saintsflood in 1570
- Februari 1953
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Disaster of 1953
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Some flood disasters
- St Elisabeth flood 1404 - St Elisabeth flood
1421 - St Felix flood 1530 - All Saints
1570 - February 1953
- January 1976
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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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The SIGMAPLAN of 1977
a) reinforce all river embankments (dikes) b)
construction of flood control areas c)
construction of a storm surge barrier ds Antwerp
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The SIGMAPLAN of 1977
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The SIGMAPLAN of 1977
a) reinforce all river embankments (dikes) b)
construction of flood control areas c)
construction of a storm surge barrier ds Antwerp
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The SIGMAPLAN of 1977
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The SIGMAPLAN of 1977
a) reinforce all river embankments (dikes) b)
construction of flood control areas c)
construction of a storm surge barrier ds Antwerp
KBR
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The SIGMAPLAN of 1977
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. benefits
• no pay back during project life (100 year)
• ? construction of barrier postponed indefenitely

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The SIGMAPLAN of 1977
Realized - 80 of all planned embankment
works - 12 of 13 planned CIAs 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 of the SIGMAPLAN
1. Introduction and situation 2. History of the
Sigmaplan 3. Updating is necessary 4. How to do
it ? New approaches
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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)
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Updating is necessary
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Updating is necessary
60 cm
1 / 70 year (7,83 m TAW) situation now 1 /
350 year (8,24 m TAW) with CFA KBR
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Updating of the SIGMAPLAN
1. Introduction and situation 2. History of the
Sigmaplan 3. Updating is necessary 4. How to do
it ? New approaches
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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
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Controlled Inundation Areas (CIA)
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180 potential CIAs (15 000 ha) have been
identified
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CIAs submitted to a multi-criteria analysis

• Compatibility with existing laws and regulations
• Influence upon quality of life of the
  surroundings
• Influence upon socio/economic activities
• Consequences for drainage
• Cost

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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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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 costsdikes, quay walls,
barriers, CIA s
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Principles of dike heightening

• function of the present situation
• ordinary dike
• dike with retention wall
• retention wall
• available space at landside of the existing dike
• technical limitations

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Stap 1 typeoplossingen bij klassieke dijk
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Quay wall heightening

• Case by case solutions mobile or fixed
  constructions
• Special case for Antwerp
• the quay has to be renovated anyway (grouting
  with anchoring)
• not higher than 8 m TAW
• if higher
• 1 km with mobile system
• 5 km with retention wall

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cost calculation of CIA

• included
• ground works
• road works
• public utilities displacement
• sluice constructions
• pumping stations
• drainage works
• expropriation costs for dikes
• compensation of woods

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maintenance and operation costs

• dikes on the basis of data from the Flemisch
  Waterway Authority
• Pumping stations (for interrupted watercourses in
  CIA) personel cost and electricity

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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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Whats 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 time
• Mainenance (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 2010
• Cost and benefits calculated up to 2100
• Residual 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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Investment costs

• Cost estimations of cost model (for works in B)
  or from Netherlands (for impacts in NL)
• all constructions start in 2010
• Construction period determined by investment
  budget of 50 mio per year
• contingency factor of 15
• SVK, Overschelde bandbreedte min-max

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Operation and maintenance

• Costs based on actual maintenance costs
• storm surge barrier based on Maeslantkering NL
  (small and large maintenance costs)
• Dikes adjust actual maintenance costs of
  Flemisch Waterways Authority on basis of length
  and type of dike
• Nature 150 /ha/year

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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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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 CIAs (T1000, T2500, T4000)

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Perform the hydraulic design
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Determine the necessary CIAs out of 15000 ha
identified potential CIAs
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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 (T4000Q)
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7700 ha (T4000ontpq)
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9250 ha (T4000ontpqres)
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Top down BC analysis

• submit the alternative schemes to a Benefit Cost
  analysis
• with composite boundary conditions
• damage and risk calculation for 2000 and 2100
• in 2100 sea level rise of 60 cm
• interpolation of risks in between

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Avoided risk (1)

• Damage categories housing and furniture, trafic
  infrastructure, vehicles, industries, other
  infrastructure, agriculture, recreation,
  victimes,
• Not included damage to inveronment,
  psychological damage, costs for evacuating,
  repair costs for dikes, damage to churches,
  musea, ...

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avoided risk (2)

• damage substitution value x damage factor
  (percentage in function of inundation depth)
• victims number of victims x valuation (1mio )
• Damage increase related to economic growth (2.4
  till 2020, 1.8 after 2030 )
• Risc probability x damage
• integration damage/risk by means of risk formula

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Results of top down approach
Costs Benefits till 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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Combining safety - nature
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SIGMAPLAN FLOODSCAPE FRaME
Prosperpolder
Antwerp
KBR
Durme
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conclusions top down

• storm surge barrier design 2004 with sea level
  rise 60 cm/100 year has PBT of 40 year, but is
  the most expensive solution. With disc. 7
  PBTgt100 year
• Dike heightening and space for river have best
  score.
• Optimal solution to be defined

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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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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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KBA Zone 1 (antwerpen)
Project Maatregel 1-1 (GOGs 1024 ha) Maatregel 1-4 (Dijken 24 km tot 9.25 m)
Investment 94,07 13,05
Disc. total cost 77,81 18,25
disc. total benefit till 2100 99,65 126,67
other effects till 2100
agriculture - 20,17 0,00
visuele nuisance inhabitants -0,50 0,00
recreation 1,92 0,00
NPV till 2100 3,09 108,42
PBT (year) 84 9
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Zone 2
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KBA Zone 2 heightening of dikes ?
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KBA Zone 2 (Hamme) Waarom geen dijkverhoging ?
Project Maatregel 2-2 (GOGs ) Maatregel 2-8 (dijkverhoging)
Investeringsbedrag 80,27 46,99
Geactualiseerde totale kosten 73,46 74,23
Geactualiseerde veiligheidsbaat tot 2100 575,31 271,58
Andere effecten tot 2100
landbouw -3,70 0,00
visuele hinder omwonenden -0,25 0,00
recreatie 3,68 0,00
Totale netto geactualiseerde baten tot 2100 501,59 197,35
Terugverdientijd (jaar) 12 23
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Zone 4
or
Kalkense meersen
raising dikes
WijmeersRot en Bastenakkers
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Zone 3 (Dijle, omgeving Mechelen)
OF
Battenbroek
SVK Niel
HeindonkOude Dijlearm
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Area 5-1
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Conclusion bottom up approach

• 3 possible plans with dike heigtening and CIAs
• differences only in area 2
• 1 scheme with small barrier on Rupel remains
  possible
• SVK Niel for areas 3 and 5
• in areas 1, 2 and 4 same layout as above

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BCA optimal Sigmaplans
Project Sigmaplan 1 (Polders Kastel) Sigmaplan 2 (Polders Kastel en Hingene) Sigmaplan 3 (Polders Kastel en Durme Sigmaplan 4 (SVK Niel)
investment (million EUR) 137,35 145,99 163,68 173,77
discounted total cost 122,21 130,11 145,81 153,21
discounted benefit till 2100 731,89 736,75 723,98 704,09
Other effects till 2100
agriculture and forest -13,28 -12,35 -23,30 -7,91
visual nuisance for inhabitants -4,55 -5,18 -10,43 -1,35
nature and recreation 7,59 8,78 27,16 6,94
NPV till 2100 599,44 597,88 571,61 548,55
Pay Back time (year) 15 15 17 17
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Levels of security
Zero reference 2000 Sigmaplan 2 now Sigmaplan 2 in 2050 (22 cm) Sigmaplan 2 in 2100 (60 cm)
Antwerpen 100-500 4000 500 50
Schelle 500 2500 500 50
Temse 500 1000 500 50
Sint-Amands 100 1000 500 50
Dendermonde 100 1000 500 50
Berlare 50 1000 500 50
Wetteren 100 2500 1000 500
Melle 25 1000 500 100
Mechelen 500 2500 1000 100
Level of security drops in future. Additional
CIAs to be reserved for 2050 Dimensioning
starting from Sigma2 and looking for optimal
investment in 2050
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Sigmaplan 2050 compementary measures if sea
level rises
Project Sigmaplan 2 2050 optie 1 Sigmaplan 2 2050 optie 2 Sigmaplan 2 2050 optie 3
Investeringsbedrag 94,90 90,34 59,43
Geactualiseerde totale kosten 97,40 96,93 63,93
Geactualiseerde veiligheidsbaat tot 2100 65,96 48,22 76,14
Andere effecten tot 2100    
landbouw -4,31 -18,32 -2,77
visuele hinder omwonenden -4,91 -15,17 -11,69
recreatie 6,09 31,15 7,06
Totale netto geactualiseerde baten tot 2100 -34,56 -51,04 4,81
Terugverdientijd (jaar) 79 gt100 jaar 51
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Optimale sigmaplan vanuit kosten-baten standpunt
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Optimal sigmaplan

• Dijkverhoging Antwerpen-KBR (9-9.25 8.75 m TAW in
  totaal 24 km)
• Extra overstromingsgebieden (1325 ha)
• Zeeschelde rond Hingene, Steendorp (314 ha)
• 100_01 Oudbroekpolder (132 ha), Schelandpolder
  (55 ha), 100_04 Schouselbroek (127 ha)
• Zeeschelde rond Hamme, Kastel (274 ha)
• 100_09 Blankaart (125 ha), 100_10 Zwijn, Grote
  en Kleine Wal (149 ha)
• Zeeschelde opwaarts Dendermonde (336 ha)
• 100_28 Wijmeers (182 ha), 100_31 Rot en
  Bastenakkers (154 ha)
• Dijle, Zenne monding (212 ha)
• 131_01 Heindonk (146 ha), 131_03 Oude Dijlearm
  (66 ha)
• Dijle opwaarts Mechelen (187 ha)
• 130_07 Broek Rijmenam (67 ha), 130_08 Hoogdonk
  (122 ha)
• Reservatiegebieden 2050 (656 ha)
• 100_03 Broekpolder te Hingene (206 ha)
• 100_13 Vlassenbroekse polder (138 ha)
• 100_14 Krabbendijkse polder (102 ha)
• 131_02 Battenbroek (210 ha)

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Security levels with amplified Sigma 2
Sigmaplan 2 in 2050 (22 cm) Sigmaplan 2 beveiliging 2050 optie 1 Sigmaplan 2 beveiliging 2050 optie 2 Sigmaplan 2 beveiliging 2050 optie 3
Antwerpen 500 4000 () 4000 () 4000 ()
Schelle 500 1000 1000 1000
Temse 500 1000 1000 1000
Sint-Amands 500 1000 1000 2500
Dendermonde 500 1000 1000 1000
Berlare 500 1000 1000 1000
Wetteren 1000 4000 2500 4000
Melle 500 1000 1000 1000
Mechelen 1000 4000 10000 4000
() mits verhoging van keermuur op de kaaien te
Antwerpen met 50 cm
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Final result
Costs Benefits till 2100 Other PBTyear
SVK Oosterweel 387 727 - 1 41
Dikes T2500 240 691 - 27
CIAs (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 CIAs
• level of overflow levees in the CIAs

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Influence of sea level rise on Sigma2
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General conclusions

1. uncertainty is large, but conclusions remain
   valid.
2. optimised Sigmaplan always better than a storm
   surge barrier
3. possibility in overinvesting in security is
   reduced (Sigmaplan2 also pays itself back in
   worst cases).
4. Possibility in underinvestment is reduced because
   of flexibility (reserved areas).

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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
  (01-07-2005?)