Presentation by Kimberley Koudstaal, WaterProof Marine Consultancy & Services B.V., The Netherlands, at the Delft3D and XBeach User Day: Coastal morphodynamics, during Delft Software Days - Edition 2019. Wednesday, 13 November 2019, Delft.

1. Kimberley Koudstaal
13-11-2019
Effects installation Borssele
export cables

2. Introduction
Location of the
Borssele export
cables

3. Introduction
Location of the Borssele export cables

4. Research questions
1) Will the installation of the export cables affect sediment transport and
local morphological development of the study area?
2) How and to what extent will the installation affect the maintenance
dredging requirements of the navigation channel towards Antwerp?

5. Approach
Morphological assessments for Borssele cables
1) Study morphodynamic evolution of the Western Scheldt Estuary
2) Setup & calibrate numerical morphological model of the Scheldt Estuary
3) Model effects of the installation of the export cables

6. Approach
Morphological assessments for Borssele cables
1) Study morphodynamic evolution of the Western Scheldt Estuary
2) Setup & calibrate numerical morphological model of the Scheldt Estuary
3) Model effects of the installation of the export cables

7. Morphodynamic characterization

8. Morphodynamic characterization

9. Vlakte van der Raan
Morphodynamic characterization

10. Spijkerplaat area
Morphodynamic characterization
[m]

11. Spijkerplaat area
Morphodynamic characterization
[m]

12. Morphodynamic characterization

13. Morphodynamic characterization

14. Morphodynamic characterization

15. Morphodynamic characterization

16. Morphodynamic characterization

17. Morphodynamic characterization

18. Morphodynamic characterization

19. Morphodynamic characterization

20. Morphodynamic characterization

21. Morphodynamic characterization

22. Morphodynamic characterization

23. Morphodynamic characterization
SouthNorth

24. Morphodynamic characterization

25. Approach
Morphological assessments for Borssele cables
1) Study morphodynamic evolution of the Western Scheldt Estuary
2) Setup & calibrate numerical morphological model of the Scheldt Estuary
3) Model effects of the installation of the export cables

26. Delft3D model Scheldt Estuary
Mesh of the used overall Scheldt model

27. Delft3D model Western Scheldt Estuary
Mesh of the applied detailed model

28. Model validation
Comparison of simulated water levels and harmonically analysed
measured waterlevels

29. Model validation
Cross-sections discharge measurements 2017

30. Model validation

31. Model validation

32. Model results; morphodynamic
Parameter Value
Timestep
3 seconds (Courant number 7-8 in Navigation channel and approx. 1 in
shallow areas)
2D/3D 2DH model
Simulation period Neap-spring cycle + spinup period (15 days total in summer 2018)
Sediment fractions
150, 200, 250 µm distinguished in a fraction where sediment is dumped
and a base layer
Model bed level 2015 & 2017
Roughness formulation
Spatial variation of Manning values (0.02 at North-Sea up to 0.027 in
Western Scheldt
Horizontal eddy viscosity 1.0
Horizontal eddy diffusivity 1.0
Sediment transport formulation Van Rijn (1993)
Morphological factor 13, to simulate a period of approx. 185 days (half year)
Waves Average wave conditions Hs = 1.0 m, Tp = 5.7 sec, Dir = 250 degrees

33. Model results; morphodynamic
Parameter Value
Timestep
3 seconds (Courant number 7-8 in Navigation channel and approx. 1 in
shallow areas)
2D/3D 2DH model
Simulation period Neap-spring cycle + spinup period (15 days total in summer 2018)
Sediment fractions
150, 200, 250 µm distinguished in a fraction where sediment is dumped
and a base layer
Model bed level 2015 & 2017
Roughness formulation
Spatial variation of Manning values (0.02 at North-Sea up to 0.027 in
Western Scheldt
Horizontal eddy viscosity 1.0
Horizontal eddy diffusivity 1.0
Sediment transport formulation Van Rijn (1993)
Morphological factor 13, to simulate a period of approx. 185 days (half year)
Waves Average wave conditions Hs = 1.0 m, Tp = 5.7 sec, Dir = 250 degrees

34. Model results; morphodynamic
Parameter Value
Timestep
3 seconds (Courant number 7-8 in Navigation channel and approx. 1 in
shallow areas)
2D/3D 2DH model
Simulation period Neap-spring cycle + spinup period (15 days total in summer 2018)
Sediment fractions
150, 200, 250 µm distinguished in a fraction where sediment is dumped
and a base layer
Model bed level 2015 & 2017
Roughness formulation
Spatial variation of Manning values (0.02 at North-Sea up to 0.027 in
Western Scheldt
Horizontal eddy viscosity 1.0
Horizontal eddy diffusivity 1.0
Sediment transport formulation Van Rijn (1993)
Morphological factor 13, to simulate a period of approx. 185 days (half year)
Waves Average wave conditions Hs = 1.0 m, Tp = 5.7 sec, Dir = 250 degrees

35. Model results; morphodynamic
Parameter Value
Timestep
3 seconds (Courant number 7-8 in Navigation channel and approx. 1 in
shallow areas)
2D/3D 2DH model
Simulation period Neap-spring cycle + spinup period (15 days total in summer 2018)
Sediment fractions
150, 200, 250 µm distinguished in a fraction where sediment is dumped
and a base layer
Model bed level 2015 & 2017
Roughness formulation
Spatial variation of Manning values (0.02 at North-Sea up to 0.027 in
Western Scheldt
Horizontal eddy viscosity 1.0
Horizontal eddy diffusivity 1.0
Sediment transport formulation Van Rijn (1993)
Morphological factor 13, to simulate a period of approx. 185 days (half year)
Waves Average wave conditions Hs = 1.0 m, Tp = 5.7 sec, Dir = 250 degrees

36. Model results; morphodynamic
Parameter Value
Timestep
3 seconds (Courant number 7-8 in Navigation channel and approx. 1 in
shallow areas)
2D/3D 2DH model
Simulation period Neap-spring cycle + spinup period (15 days total in summer 2018)
Sediment fractions
150, 200, 250 µm distinguished in a fraction where sediment is dumped
and a base layer
Model bed level 2015 & 2017
Roughness formulation
Spatial variation of Manning values (0.02 at North-Sea up to 0.027 in
Western Scheldt
Horizontal eddy viscosity 1.0
Horizontal eddy diffusivity 1.0
Sediment transport formulation Van Rijn (1993)
Morphological factor 13, to simulate a period of approx. 185 days (half year)
Waves Average wave conditions Hs = 1.0 m, Tp = 5.7 sec, Dir = 250 degrees

37. Model results; morphodynamic
Parameter Value
Timestep
3 seconds (Courant number 7-8 in Navigation channel and approx. 1 in
shallow areas)
2D/3D 2DH model
Simulation period Neap-spring cycle + spinup period (15 days total in summer 2018)
Sediment fractions
150, 200, 250 µm distinguished in a fraction where sediment is
dumped and a base layer
Model bed level 2015 & 2017
Roughness formulation
Spatial variation of Manning values (0.02 at North-Sea up to 0.027 in
Western Scheldt
Horizontal eddy viscosity 1.0
Horizontal eddy diffusivity 1.0
Sediment transport formulation Van Rijn (1993)
Morphological factor 13, to simulate a period of approx. 185 days (half year)
Waves Average wave conditions Hs = 1.0 m, Tp = 5.7 sec, Dir = 250 degrees

38. Alpha + Beta cables
Model results; morphodynamic

39. Alpha + Beta cables
Model results; morphodynamic

40. Model results; morphodynamic

41. Model results; morphodynamic
Verification of model with actual dredging volumes

42. Model results; morphodynamic
Verification of model with actual dredging volumes
Sill of Borssele
(x 1000 m³)
Sill of Vlissingen
(x1000 m³)
Honte
(x1000 m³)
Total
(x 1000 m³)
Actual dredged
volumes 2017
1290 190 650 2130

43. Model results; morphodynamic
Verification of model with actual dredging volumes
Sill of Borssele
(x 1000 m³)
Sill of Vlissingen
(x1000 m³)
Honte
(x1000 m³)
Total
(x 1000 m³)
Model; 2017, 150 µm 2150 40 30 2220
Actual dredged
volumes 2017
1290 190 650 2130

44. Model results; morphodynamic
Verification of model with actual dredging volumes
Sill of Borssele
(x 1000 m³)
Sill of Vlissingen
(x1000 m³)
Honte
(x1000 m³)
Total
(x 1000 m³)
Model; 2017, 150 µm 2150 40 30 2220
Model; 2017, 250 µm 790 590 840 2220
Actual dredged
volumes 2017
1290 190 650 2130

45. Model results; morphodynamic
Verification of model with actual dredging volumes
Sill of Borssele
(x 1000 m³)
Sill of Vlissingen
(x1000 m³)
Honte
(x1000 m³)
Total
(x 1000 m³)
Model; 2017, 150 µm 2150 40 30 2220
Model; 2017, 200 µm 1190 270 390 1850
Model; 2017, 250 µm 790 590 840 2220
Actual dredged
volumes 2017
1290 190 650 2130

46. Model results; morphodynamic
Verification of model with actual dredging volumes
Simulations have been performed for:
▪ Wave related transport
▪ Flow related transport
▪ Slope factor (α-Bn/Bs)

47. Effect of model settings
Model results; morphodynamic

48. Effect of model settings
Model results; morphodynamic

49. Effect of model settings
Model results; morphodynamic

50. Approach
Morphological assessments for Borssele cables
1) Study morphodynamic evolution of the Western Scheldt Estuary
2) Setup & calibrate numerical morphological model of the Scheldt Estuary
3) Model effects of the installation of the export cables

51. Approach
Morphological assessments for Borssele cables
1) Study morphodynamic evolution of the Western Scheldt Estuary
2) Setup & calibrate numerical morphological model of the Scheldt Estuary
3) Model effects of the installation of the export cables
a) Effects on local morphology dynamics
b) Effects on dredge requirements

52. Model results, channel model
Dredging (blue) and dumping (red) locations for the cables

53. Model results – Scenario 2
Morphodynamic results after 6 months for the present situation

54. Model results – Scenario 2
Morphodynamic results after 6 months for the cables

55. Model results – Scenario 2

56. Model results – Scenario 2

57. Morphodynamic characterization

58. Model results
Effect on total volume of sediment at the navigation channel
Situation
Sedimentation
Present
situation
Sedimentation
Present situation
+ cable
Difference in
sedimentation
(m)
Difference in
sedimentation
(%)
2017
Alpha, 200 µm 4,768,000 4,859,000 91,000 1.9
Beta, 200 µm 4,768,000 4,814,000 46,000 1.0

59. Model results
Maintenance requirement of the navigation channel
Simulation
Additional volume to be
dredged [m³] Alpha
Additional volume to be dredged
[m³] Beta
2017, 200 um -9.500 (-0.5%) -500 (-nihil%)

60. Model results
Maintenance requirement of the navigation channel
• Changes are small and fall within the uncertainty bandwidth of the model
Simulation
Additional volume to be
dredged [m³] Alpha
Additional volume to be dredged
[m³] Beta
2017, 200 um -9.500 (-0.5%) -500 (-nihil%)

61. Research questions
1) Will the installation of the export cables affect sediment transport and
local morphological development of the study area?
2) How and to what extent will the installation affect the maintenance
dredging requirements of the navigation channel towards Antwerp?

62. Research questions
1) Will the installation of the export cables affect sediment transport and
local morphological development of the study area?
2) How and to what extent will the installation affect the maintenance
dredging requirements of the navigation channel towards Antwerp?
1) Local effects can be seen, but the large scale morphology remains largely
unaffected

63. Research questions
1) Will the installation of the export cables affect sediment transport and
local morphological development of the study area?
2) How and to what extent will the installation affect the maintenance
dredging requirements of the navigation channel towards Antwerp?
1) Local effects can be seen, but the large scale morphology remains largely
unaffected
2) The effects on the dredging requirements are small and fall within the
uncertainty bandwidth of the model