Presentation by Shailesh van der Steeg, University of South Carolina, USA, at the Delft3D - User Days (Day 1: Hydrology and hydrodynamics), during Delft Software Days - Edition 2018. Monday, 12 November 2018, Delft.

1. Floodplain Circulation Dynamics
Shailesh van der Steeg | University of South Carolina

2. Floodplain Circulation Dynamics
N

3. 3River Floodplain
Floodplain Circulation Dynamics

4. What do we want to do?
Insight into conditions, processes and complexity of floodplain circulation
• Flooding and drainage of surface water
Why?
• Floodplain circulation has not been studied extensively
• Provide a baseline of how flow in a natural regime occurs
• Hazard mitigation or ecosystem stability
4
Floodplain Circulation Dynamics

5. No exchange
5
River-floodplain exchange
Flow and Transport
Exchange
• Below bank full flow conditions
• No surface water exchange
• Stage rises above levee elevation
• Surface water exchange
Figures not drawn to scale
A’
A
A’: Innerbank
A: Outerbank
by overbank flow
Top view
Stage
Stage

6. • There are other forms of exchange
• Floodplain channels
6
River-floodplain exchange
Flow and Transport
Figures not drawn to scale
• Different types of floodplain channels:
• Long-lived, permanent
• Transient
A’
A
Top view
A’: Innerbank
A: Outerbank
Stage

7. 7
River-floodplain exchange
Levee
Channel Bed
River bed
Figures not drawn to scale
Levee

8. Congaree River & Floodplain
Study Site

9. Study Site: Where in the world?
9
South Carolina
Southwest of Columbia,
South Carolina

10. Study Site: Congaree River & Floodplain
10
N

11. Study Site: Topography
11
N
Elevation [m], NAVD88
38 22

12. • Floodplain channels with
levees
• Range in dimensions of
channels
• Oxbow lakes
• Scroll bars
12
Study Site: Relief
Local Relief

13. Acoustic Doppler Current Profiler:
• During high flow events
13
Study Site: Data collection
Pressure sensors:
• 32 sensors employed in the field

14. Study Site: Data collection
14
N

15. 15
Study Site: Data collection
Waterlevel,detrended[m]
Time

16. Study Site: Data collection
16
N
0.12 0.63
0.08
0.71
0.17
0.71
Pearson Correlation Coefficient

17. Hydrodynamic modeling
High resolution modeling using Delft3D FM Suite

18. • Channelized and overland flow
• 2D or 3D
• Floodplain topography important (e.g. Alsdorf et al., 2007)
• Adequate representation of topographic features
• Computational grid
• Efficient
• Sufficient resolution
• Resolve ‘small’ scale flow dynamics
• Sediment transport
18
Floodplain hydrodynamic modeling

19. Northern Floodplain
Congaree River
Southern Floodplain
Computational Grid
N

20. Computational Grid: Structured Mesh?
N

21. Computational Grid: Flexible Mesh!
N

22. Computational Grid: Flexible Mesh!
N

23. Observation Cross-sections
Computational Grid: Grid Snapped Features
N

24. Computational Grid: Flexible Mesh!
N
Local mesh refinement

25. • Collected data will provide a high level of validation
• Different (artificial) flow scenarios to investigate inundation patterns
• Sediment transport
• Implications for sediment transport
25
Looking forward…

26. 26
Looking forward…

27. Floodplain Circulation Dynamics
Shailesh van der Steeg | University of South Carolina