By Chris O’Connor
Outline
 Salter’s Duck
 Dynamics of Sediment Transport
 Results of Numerical Simulations
Salter’s Duck
Salter’s Duck
Water line
Determining the Amount of Energy
Captured
 ρ – water density
 g – gravitational acceleration
 H – wave height
 L – total length of wave engaging members
 E – efficiency of the wave farm
Wave Height Reduction
 Wave energy
dissipation will reduce
sediment transport.
Alongshore Current
• Wave momentum enters water column during
breaking
• Alongshore component drives a current
• → advects suspended sediment
Photo: Jeremy Bryant
Plan view
Alongshore Sediment Flux
waves
alongshore current
Qs
h
x
shore—plan view
C. of nearshore Sediment:
h/t = (-1/D)Qs/x
eros.,
accretion
D
cross section
Alongshore Sediment Flux
Qs = K2 Ho12/5 cos 6/5(o -  ) sin (o -  )
Qs
45°
h
x
shore—plan view
90°
o - 
Numerical Model
•
Discretizes:
h/t = (-1/D)Qs /x,
•
Partly rule-based (wave shadowing)
Numerical Model
•
New wave-approach angle daily
PDF = wave climate
Example: Carolina Capes
Model Setup
Thank you Zack!!
Cross Shore Distance (km)
Initial Condition Coastline
0
20
40
60
80
100
1080
1100
1120
1140
1160
1180
1200
1220
Alongshore Distance (km)
1240
1260
Cross Shore Distance (km)
Results
Change in
Cell Sand
Natural Simulation
0
1
20
1km2 of
accretion
0.5
40
0
60
-0.5
80
100
1100
1150
1200
Alongshore Distance (km)
1250
-1
1km2 of
erosion
Cross Shore Distance (km)
Results
Change in
Cell Sand
Simulation 1
0
1
20
0.5
40
0
60
-0.5
80
100
1100
1150
1200
Alongshore Distance (km)
1250
-1
Cross Shore Distance (km)
Results
Change in
Cell Sand
Simulation 2
0
1
20
0.5
40
0
60
-0.5
80
100
1100
1150
1200
Alongshore Distance (km)
1250
-1
Cross Shore Distance (km)
Results
Change in
Cell Sand
Simulation 3
0
1
20
0.5
40
0
60
-0.5
80
100
1100
1150
1200
Alongshore Distance (km)
1250
-1
Cross Shore Distance (km)
Results
Change in
Cell Sand
Simulation 4
0
1
20
0.5
40
0
60
-0.5
80
100
1100
1150
1200
Alongshore Distance (km)
1250
-1
Cross Shore Distance (km)
Results
Change in
Cell Sand
Simulation 5
0
1
20
0.5
40
0
60
-0.5
80
100
1100
1150
1200
Alongshore Distance (km)
1250
-1
Cross Shore Distance (km)
Results
Change in
Cell Sand
Simulation 6
0
1
20
0.5
40
0
60
-0.5
80
100
1100
1150
1200
Alongshore Distance (km)
1250
-1
Cross Shore Distance (km)
Results
Change in
Cell Sand
Simulation 7
0
1
20
0.5
40
0
60
-0.5
80
100
1100
1150
1200
Alongshore Distance (km)
1250
-1
Cost of Renourishment
 Found all
erosion cells
 Calculated
volume of sand
lost
 Charged $10/m3
to replace
Cost of Additional Renourishment
Simulation
Cost per year in USD
1
11,930,000
2
8,686,000
3
11,260,000
4
9,883,000
5
19,164,000
6
12,042,000
7
14,378,000
Energy Output
Simulation
Energy Output per year
in kWh
Cost of dredging per
kWh in USD
1
2.3*109
0.005
2
2.3*109
0.004
3
2.3*109
0.005
4
4.6*109
0.002
5
4.6*109
0.004
6
4.6*109
0.003
7
6.9*109
0.002
Conclusions
 The wave farm would cause a significant erosion signal
 This erosion could be alleviated by 2-5%
renourishment tax
 Model Limitations
 No diffraction
 Only applicable for sandy coasts