1. 1 ESPACE INTERREG III B De Smet Michel Stefaan Nollet Wim Dauwe District Sea-Scheldt vrijdag 26 juni 2015 Updating of the SIGMAPLAN

2. 2 1. Introduction and situation 2. History of the Sigmaplan 3. Updating is necessary 4. How to do it ? New approaches

3. 3 Estuary of the Scheldt 355 km river length 21.863 km 2 10 500 000 people Sea Scheldt

4. 4

5. 5

6. 6 Updating of the SIGMAPLAN 1. Introduction and situation 2. History of the Sigmaplan 3. Updating is necessary 4. How to do it ? New approaches

7. 7 - St Elisabethflood in 1404 - St Elisabetflood in 1421 - St Felixflood in 1530 - All Saintsflood in 1570 Some flood disasters - Februari 1953

8. 8 1836 slachtoffers Disaster of 1953

9. 9 - St Elisabeth flood 1404 - St Elisabeth flood 1421 - St Felix flood 1530 - All Saints 1570 - February 1953 - January 1976 Some flood disasters

10. 10 Flood disaster of 1976

11. 11 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

12. 12 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 zone 1 : 11,00 m TAW zone 2 : 8,35 m TAW zone 3 : 8,00 m TAW

13. 13 The SIGMAPLAN of 1977

14. 14 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

15. 15 ScheldtCIA 1 2 3 4 ringdikeweir 1 2 3 4 The SIGMAPLAN of 1977

16. 16 The SIGMAPLAN of 1977 KBR a) reinforce all river embankments (dikes) b) construction of flood control areas c) construction of a storm surge barrier ds Antwerp

17. 17 90 m 54 m lift gates sector gates 125 m The SIGMAPLAN of 1977 2003 : 1.000.000.000 EUR

18. 18 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

19. 19 The SIGMAPLAN of 1977 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

20. 20 Updating of the SIGMAPLAN 1. Introduction and situation 2. History of the Sigmaplan 3. Updating is necessary 4. How to do it ? New approaches

21. 21 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)

22. 22 Updating is necessary We are confronted with : - stronger tides (GHW  en GLW  ) - rising sea level - increasing frequency of storms - increasing peak discharges of run-off

23. 23 Updating is necessary 60 cm 1 / 70 year (7,83 m TAW) : situation now 1 / 350 year (8,24 m TAW) : with CFA KBR

24. 24 Updating of the SIGMAPLAN 1. Introduction and situation 2. History of the Sigmaplan 3. Updating is necessary 4. How to do it ? New approaches

25. 25 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

26. 26 Raising the dikes

27. 27 Build a barrier ds/ Antwerp

28. 28 or small barriers at Mechelen and Lier…

29. 29 Controlled Inundation Areas (CIA)

30. 30 180 potential CIA’s (15 000 ha) have been identified

31. 31 CIA’s : 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 …

32. 32 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

33. 33 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

34. 34 Modelled area

35. 35 Complete model

36. 36 Modeling of flood prone areas

37. 37 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

38. 38 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

39. 39 Model for estimating construction costs and operation & maintenance costs dikes, quay walls, barriers, CIA ’s

40. 40 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

41. 41 Stap 1 : typeoplossingen bij klassieke dijk

42. 42 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

43. 43 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 …

44. 44 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

45. 45 Large storm surge barrie Antwerp barrier: alternative design after existing construction along Nieuwe Waterweg (Netherlands)

46. 46 Small storm surge barriers on Rupel Mechelen en Lier: scaling the Beernem barrier (B) Niel (Rupel): scaling the Hartel barrier (NL)

47. 47 Construction period Estimated on basis of : available budgets for Sigma : 50 million EUR / year

48. 48 Model for Benefit Cost Analysis

49. 49 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)

50. 50 What’s compared CostsBenefitsadditional 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

51. 51 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

52. 52 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

53. 53 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

54. 54 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

55. 55 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

56. 56 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)

57. 57 Perform the hydraulic design

58. 58 Determine the necessary CIA’s out of 15000 ha identified potential CIA’s

59. 59 1800 ha (T1000)

60. 60 2330 ha (T2500)

61. 61 2800 ha (T4000)

62. 62 6900 ha (T4000+Q)

63. 63 7700 ha (T4000+ontp+q)

64. 64 9250 ha (T4000+ontp+q+res)

65. 65 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

66. 66 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,...

67. 67 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

68. 68 Results of top down approach CostsBenefits till 2100 OtherPBT year Storm surge barrier Antwerp 387727- 141 Dikes T2500240691-27 CIA ( 1800 ha )140648-1817 CIA with CRT ( 1800 ha) 1516483314 milj Euro, discounted to 2004, 4% disc.

69. 69 Combining safety - nature þ input from the ecological rehabilitation plan and ecosystem model for the Scheldt estuary !

70. 70 ScheldtFCA with CRT ringdikeweir 1 2 3 4 Combining safety - nature

71. 71 SIGMAPLAN : FLOODSCAPE & FRaME Prosperpolder Durme Antwerp KBR

72. 72 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%: PBT>100 year Dike heightening and space for river have best score. Optimal solution to be defined

73. 73 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

74. 74 Risk map anno 2100: damage centers

75. 75 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

76. 76 Methodology: 5 optimization areas

77. 77 Zone 1 Or

78. 78 KBA Zone 1 (antwerpen) Project Maatregel 1-1 (GOG’s 1024 ha) Maatregel 1-4 (Dijken 24 km tot 9.25 m) Investment94,0713,05 Disc. total cost77,8118,25 disc. total benefit till 210099,65126,67 other effects till 2100 agriculture- 20,170,00 visuele nuisance inhabitants-0,50± 0,00 recreation1,920,00 NPV till 21003,09108,42 PBT (year)849

79. 79 Zone 2

80. 80 KBA Zone 2: heightening of dikes ?

81. 81 KBA Zone 2: (Hamme) Waarom geen dijkverhoging ? Project Maatregel 2-2 (GOG’s ) Maatregel 2-8 (dijkverhoging) Investeringsbedrag80,2746,99 Geactualiseerde totale kosten73,4674,23 Geactualiseerde veiligheidsbaat tot 2100575,31271,58 Andere effecten tot 2100 landbouw-3,700,00 visuele hinder omwonenden-0,25± 0,00 recreatie3,680,00 Totale netto geactualiseerde baten tot 2100 501,59197,35 Terugverdientijd (jaar)1223

82. 82 Zone 4 Kalkense meersen Wijmeers Rot en Bastenakkers or raising dikes

83. 83 Zone 3 (Dijle, omgeving Mechelen) OF SVK Niel Battenbroek Heindonk Oude Dijlearm

84. 84 Area 5-1

85. 85 Conclusion bottom up approach 3 possible plans with dike heigtening and CIA’s –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

86. 86 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)137,35145,99163,68173,77 discounted total cost122,21130,11145,81153,21 discounted benefit till 2100731,89736,75723,98704,09 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 recreation7,598,7827,166,94 NPV till 2100599,44597,88571,61548,55 Pay Back time (year)15 17

87. 87 Levels of security Zero reference 2000Sigmaplan 2 nowSigmaplan 2 in 2050 (+22 cm) Sigmaplan 2 in 2100 (+60 cm) Antwerpen100-500400050050 Schelle500250050050 Temse500100050050 Sint-Amands100100050050 Dendermonde100100050050 Berlare50100050050 Wetteren10025001000500 Melle251000500100 Mechelen50025001000100 Level of security drops in future. Additional CIA’s to be reserved for 2050 Dimensioning starting from Sigma2 and looking for optimal investment in 2050

88. 88 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 94,9090,3459,43 Geactualiseerde totale kosten 97,4096,9363,93 Geactualiseerde veiligheidsbaat tot 2100 65,9648,2276,14 Andere effecten tot 2100 landbouw -4,31-18,32-2,77 visuele hinder omwonenden -4,91-15,17-11,69 recreatie 6,0931,157,06 Totale netto geactualiseerde baten tot 2100 -34,56-51,044,81 Terugverdientijd (jaar) 79>100 jaar51

89. 89 Optimale sigmaplan vanuit kosten-baten standpunt

90. 90 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)

91. 91 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 Antwerpen5004000 (*) Schelle5001000 Temse5001000 Sint-Amands5001000 2500 Dendermonde5001000 Berlare5001000 Wetteren1000400025004000 Melle5001000 Mechelen10004000100004000 (*) mits verhoging van keermuur op de kaaien te Antwerpen met 50 cm

92. 92 Final result CostsBenefits till 2100 OtherPBT year SVK Oosterweel387727- 141 Dikes T2500240691-27 CIA’s ( 1800 ha )140648-1817 CIA as RFA ( 1800 ha) 1516483314 Optimal sigmaplan (With CIA1325 +656 ha) 143752-1115 milj Euro, discounted to 2004 with 4% disc.

93. 93 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

94. 94 Influence of sea level rise on Sigma2

95. 95 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).

96. 96 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?)