1. Modeling the hydro-morphodynamics of the
mouth of the Scheldt estuary
Jebbe van der Werf1, Tomas van Oyen2, Bart de Maerschalck2, Abdel Nnafie2,
Arnold van Rooijen1, Marcel Taal1, Pieter Koen Tonnon1, Toon Verwaest2,
Lodewijk de Vet1, Julia Vroom1 & Mick van der Wegen1
1Deltares, The Netherlands
2Flanders Hydraulics Research, Belgium

2. 6 juli 2015
Mouth of the Scheldt estuary

3. 6 juli 2015
Management questions
Impact large-scale interventions:
- maintenance dredging
- tidal penetration
- channel morphodynamics
-…

4. 6 juli 2015
Modeling challenges
• Most previous modeling studies focussed on Western Scheldt and
further upstream (e.g. Dam et al., 2007; Van der Wegen & Roelvink, 2012)
• Complex physics: influence of tide, waves, wind and river (3D
effects)
• Sand and mud (ETM near Zeebrugge)
• Large area of interest, long time horizon (10-20 years), required
resolution ~50-100 m
• Not an easy job!
• Too many aspects for 1 single model

5. 6 juli 2015
Strategy: suite of models
1. Large-scale, long-term (~20 years) hydro-morphodynamics: 2DH
model entire Scheldt estuary (sand only)
2. Short-term (~1 year) morphodynamics: 3D sand-mud-bed model
mouth of estuary
3. Large-scale mud dynamics: 3D mud model entire Scheldt estuary
(no sand, “offline”, no bed level change)

6. 6 juli 2015
Strategy: suite of models
1. Large-scale, long-term (~20 years) hydro-morphodynamics: 2DH
model entire Scheldt estuary (sand only)
2. Short-term (~1 year) morphodynamics: 3D sand-mud-bed model
mouth of estuary
3. Large-scale mud dynamics: 3D mud model entire Scheldt estuary
(no sand, “offline”, no bed level change)

7. 6 juli 2015
Delft3D-NeVla model
Resolution
~400 m North Sea
50-100 m Western Scheldt
~10 m Sea Scheldt

8. 6 juli 2015
Delft3D-NeVla model
2x2 coarser wave grid

9. 6 juli 2015
M2 component water level

10. 6 juli 2015
M2-M4 tidal asymmetry

11. 6 juli 2015
2014 measurement campaign

12. 6 juli 2015
Validation flow velocities

13. 6 juli 2015
Validation wave heights and periods

14. 6 juli 2015
Long-term morphological development 1964-2011
Source: Elias & Van
der Spek (2015)

15. 6 juli 2015
Delft3D morphological model
• Hindcast morphological development 1985-2011
• Input reduction: 1 single morphological tide and 6 representative wave
conditions (mormerge)
• Morphological acceleration factor of 104
• Time-varying dredging and dumping
• Non-erodible layers

16. 6 juli 2015
First explorative simulations

17. 6 juli 2015
Conclusions and future work
1. Assessment impact large-scale morphological interventions
mouth Scheldt estuary requires suite of models
2. 2DH Delft3D model Scheldt estuary that predicts water levels,
flow velocities, discharges and wave heights well
3. Set-up morphological model Scheldt estuary
Work in progress:
• Hindcast morphological development 1984-2011
• 3D sand-mud morphological model of mouth Scheldt estuary
• Scenario simulations