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

Updating of the SIGMAPLAN. ESPACE INTERREG III B De Smet Michel Stefaan Nollet Wim Dauwe District Sea-Scheldt woensdag 3 september 2014. 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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ESPACE INTERREG III B De Smet Michel Stefaan Nollet Wim Dauwe District Sea-Scheldt

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  1. Updating of the SIGMAPLAN ESPACE INTERREG III B De Smet Michel Stefaan Nollet Wim Dauwe District Sea-Scheldt woensdag 3 september 2014

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

  3. Sea Scheldt Estuary of the Scheldt 355 km river length 21.863 km2 10 500 000 people

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

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

  6. 1836 slachtoffers Disaster of 1953

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

  8. Flood disaster of 1976

  9. 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

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

  11. The SIGMAPLAN of 1977

  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

  13. The SIGMAPLAN of 1977 CIA Scheldt ringdike weir 2 2 3 3 1 1 4 4

  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 KBR

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

  16. 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

  17. 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

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

  19. 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)

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

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

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

  23. 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

  24. Raising the dikes

  25. Build a barrier ds/ Antwerp

  26. or small barriers at Mechelen and Lier…

  27. Controlled Inundation Areas (CIA)

  28. 180 potential CIA’s (15 000 ha) have been identified

  29. 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

  30. 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

  31. Modelled area

  32. Complete model

  33. Modeling of flood prone areas

  34. 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

  35. 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

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

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

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

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

  40. Model for Benefit Cost Analysis

  41. 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)

  42. What’s compared

  43. 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

  44. 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

  45. 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

  46. 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)

  47. Perform the hydraulic design

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

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