cepd03 coastal sediment transport 6
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8/10/2019 CEPD03 Coastal Sediment Transport 6
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Coastal Sediment Transport
CEPD03
Lecture 6
Prof. Dano Roelvink
Dr. Jan van de Graaff
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Contents
• Overview of problems
• Bed shear stress by waves and current
• Sediment transport by waves and current
• Longshore sediment transport• Coastline changes
• Cross-shore sediment transport
• Dune erosion• Sedimentation in channels and trenches
• Stability of channels and inlets
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Cross-shore transport
• Example comparison Delft3D with Delta
Flume test
• Hs= 1.4 m, Tp = 5 s
• Barred profile
• Lots of measurements
• Prototype conditions
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Delft3D
• Process-based model
• 2Dh, 2DV or 3D
• This application 2DV
• Based on wave and roller energy balance,3D shallow water equations, 3D advection-diffusion equation
• Hydrodynamics and concentrationsreasonably well modelled
• Sediment transport rate difficult
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Initial profile
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Velocity
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Sediment concentration
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Example:
hindcast of
Delta Flume
test with
Delft3D
0 20 40 60 80 100 120 140 160 180 2000
0.5
1
1.5HRMS
0 20 40 60 80 100 120 140 160 180 2000
2
4
6
DEPTH
0 20 40 60 80 100 120 140 160 180 200
-0.2
0
0.2
0.4
0.6ETA
0 20 40 60 80 100 120 140 160 180 200-4
-2
0
2
4x 10
-5STOTX
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Concentration profiles
0 1 2 3 4 50
2
4CONCX100
0 1 2 3 4 50
1
2CONCX102
0 1 2 3 4 50
1
2CONCX115
0 1 2 3 4 50
1
2CONCX130
0 1 2 3 4 50
0.5
1CONCX141
0 1 2 3 4 50
0.5
1CONCX145
0 1 2 3 4 50
0.5
1
CONCX160
0 1 2 3 4 50
0.5
CONCX170
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Velocity profiles
-0.2 -0.1 00
2
4 RTFX100
-0.2 -0.1 00
1
2 RTFX102
-0.2 -0.1 00
1
2 RTFX115
-0.2 -0.1 00
1
2
RTFX130
-0.2 -0.1 00
0.5
1
RTFX141
-0.2 -0.1 00
0.5
1
RTFX145
-0.2 -0.1 00
0.5
1
RTFX156
-0.2 -0.1 00
0.5
1
RTFX160
-0.2 -0.1 00
0.5
RTFX170
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Dunes as coastal protection
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Dune erosion
• Fast process
• Dominated by undertow that brings sand
offshore
• Development of steep ‘scarp’
• Undercutting by waves followed by
slumping of scarp• Eventually rather flat equilibrium profile
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Dune erosion behaviour
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Behaviour in time
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Scale laws
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Scale series
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Equilibrium profile Vellinga
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Distance dune foot-limit profile
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Dutch dune erosion method
• Scarp 1:1
• eq. profile acc.
to 8.4.1
• ends at 8.4.2
• seaward slope
1:12.5
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sensitive parameters
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Applying method
• Put equilibrium profile over existing profile
• compute area eroded and area accreted
• if eroded>accreted: shift seaward• if accreted>eroded: shift landward
• find location where eroded=accreted
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Tide and storm surge
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Exceedance frequency
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UCIT
• Universal Coastal Intelligence Toolkit
• Developed at Delft Hydraulics
• Matlab environment• Includes data, analysis tools and models
• Integrated environment
• Open• Easy to extend
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Overview of JARKUS profiles
-1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4
x 105
3.5
4
4.5
5
5.5
6
x 105
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Momentary CoastLine MCL
XmklLZK
: 100.3457 m tov RSP-lijn
-1000010002000300040005000
-30
-20
-10
0
10
20
30
GLW
Xmkl
Kustdwarse afstand [m]
H o o g t e l i g g i n g [ m
t o v N A P ]
MKL zone
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Trend in MCL = TCL
Xtkl(LZK) : 93.8311 m tov RSP-lijn
BKL : 89 m tov RSP-lijn
1965 1970 1975 1980 1985 199060
70
80
90
100
110
120
130
140
150
Jaren
K u s t d w a r s e a
f s t a n d [ m ]
Momentane Kustlijnen en de te Toetsen Kustlijn (met 95% betrouwb.int.)
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Dune erosion computation
A : 471.9604 m 3 /m1
T : 137.9377 m 3 /m1
P : -108.7258 m tov RSP-lijn
R : -118.2268 m tov RSP-lijn
-800-600-400-2000200400600800
-20
-15
-10
-5
0
5
10
15
20
A
Kustdwarse afstand [m tov RSP]
H o o g t e l i g g i n g [ m t o
v N A P ]
Raai: 4000 Jaar: 1987 Methode: Leidraad Duinafslag - nu (-) Norm: 1 10
-4
per jaar
afslagzonedepositiezone
P
R
kernzonebeschermingszone zeezijde