Numerical Modelling of Hydrodynamics and Morphodynamics at ...

Numerical Modelling of
Hydrodynamics and Morphodynamics
at Port Stephens, NSW, Australia
Angela Wenping Jiang
PHD Candidate

Objectives
To determine the interrelated morphodynamics
of flood-tide deltas and adjacent shorelines.
‣ Dominant hydrodynamic y processes governing g flood-tide
delta/shoreline morphodynamics;
‣ Existing sediment transport pathways and sediment
budgets;
‣ System response to extreme events;
‣ System response to climate change driven variations in
environmental forcing parameters (e.g. Sea level rise).
2

Study Site
Port Stephens is classified as a tide-dominated dominated estuary that is
locatedonawavedominated on a wave-dominated coast.
Flood-tide
delta
Port Stephens
Port Stephens (photo courtesy of DECC)

Methods
A process-based
2DH
numerical modelling approach
Hydrodynamic
Simulation
(MIKE 21 HD)
Wave Transformation
and Calculation
(MIKE 21 SW)
Sediment Transport
Calculation
Erosion/Accretion
4

Model Setup_ Mesh
5

Calibration and Validation
JB4
JB2
JB3
JB1
SB1
Port Stephens (photo courtesy of DECC)
SB2
SB4
SB3
Tomaree
6

Comparisons of Predictions and
Measurements - HD
1
0.5
[m]
0
-0.5
-1
0.5
0.4
m/s
0.3
0.2
0.1
0.0
400
300
Deg gree
200
100
0
6/03/08 7/03/08 8/03/08 9/03/08 10/03/08
Water levels (above), current speeds (middle) and directions (below) at
JB3: measured (blue) and modelled (pink)
7

Statistical Analyses
RMS (m)
RMS/max.
Variation
Correlation
Coefficient
Water 0.07-0.16 3.5-9.3% 0.97-0.98
Level
Current 004-0 0.04-0.0808 10.1-20.21-20 2 % 063-0 0.63-0.90
Velocity
Overall, good agreements between measurements and
model predictions have been achieved.
8

Comparisons of Predictions and
Measurements - SW
Hs [m]
05 0.5
0.4
0.3
at JB4:
HMeasured 02 0.2
(blue) and
0.1
Significant wave height
modelled (pink)
0.0
6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00
04-04-2008
0.6
05 0.5
0.4
Significant wave height
at SB4:
Measured (blue) and
modelled (pink)
Hs [m]
0.3
02 0.2
0.1
0
7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00
23-07-2008
9

Model Applications
Model experiment
Tides
HD
Wind
Ocean
waves
SW
Wind
Tide only
√
Tide and wind
shear
Tide and ocean
waves
Tide, ocean and
local waves
√
√
√
√
√ √ √
* Average wave conditions: Hs=1.63 m, Tp=9.57 sec, predominant wave
direction=SSE (Lord and Kulmar 2000)
* Moderate wind: southerly and westerly, speed=7.2 m/s
10

Dominant hydrodynamic processes at
Jimmy’s Beach
Zone1
Zone2
Zone3
Zone4
Zone5
Zone6
Zone7
11

Results _ Tides
12

Ocean Waves
14

Ocean Waves
15

Wind Waves
16

Comparisons s of Peak Currents
Mean currents during peak flood tide
02 0.2
0.1
0
-0.1
0.3
Zone1 Zone2 Zone3 Zone4 Zone5 Zone6 Zone7
Mean currents during peak ebb tide
0.2
0.1
0
-0.1
Zone1 Zone2 Zone3 Zone4 Zone5 Zone6 Zone7
17

Wave Orbital Velocity
1
08 0.8
m/s
0.6
0.4
Particle_bed
Particlel_surface
0.2
0
Zone1 Zone2 Zone3 Zone4 Zone5 Zone6 Zone7
18

Conclusions
Flow patterns along Jimmy’s Beach are
spatially variable.
Under SSE average wave and moderate wind
conditions:
‣ Nearshore
flows are dominated by
ocean-wave
and tidally
induced
flows.
‣ Locally generated wind waves and
wind shear appear to be relatively
insignificant.
19

Future Work
‣The effects of storm events
‣Sediment transport in swash zone
20

Acknowledgements
‣Australian Research Council
‣NSW Department of Environment and Climate
Change (DECC)
‣Great Lakes Council
‣Port Stephens Council
‣Jimmy’s s Beach Restoration Society Inc.
‣Manly Hydraulics Laboratory (MHL)
‣Australian Bureau of Meteorology (BOM)
‣Field data processed by Tim Austin, Dan Harris and
Gen Pezzimenti.
Thank you!