Modeling of long-term coastal morphodynamics of the Pomeranian Bight, southern Baltic Sea
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The 12th German-Polish Seminar on Coastal Research
including
6th International COPAF Workshop
Greifswald, 11/12th October, 2012
Modeling of long-term coastal morphodynamics of
the Pomeranian Bight, southern Baltic Sea
Junjie Deng1, Wenyan Zhang2, Joanna Dudzinska-Nowak1, Pawel Terefenko1, Andrzej Giza1,
Jan Harff1, Ralf Schneider2, and Kazimierz Furmanczyk1
1 Faculty of Geosciences, University of Szczecin, Poland, Email junjie.deng@univ.szczecin.pl
2 Institute of Physics, University of Greifswald, Germany
CoPaF ( www.copaf.pl )
Outline
• Area of Investigation
• Method of reconstruction of Paleo-DEM at ca. 1900 AD:
• Dynamic equilibrium shore model
• Inverse modeling
• The comparison with BS-LTMM long term
morphodynamic model that start with this
reconstructed DEM.
• Discussion and Summary
• Prospects of the reconstruction of Paleo-DEM at ca.
1500 AD
Coastal erosion during storm surge at Dziwnów on November 4, 1995
Photo: P. Domaradzki
Area of Investigation Bathymetry of Baltic Sea
by Seifert et al. (2001)
• Sandy coast
• cliff and dune
• Tideless
• Wave-dominated
• Odra River (Leipe et al., 1998)
- Water: 18 km3/yr
- Sediment: 42.5 x104 tons/yr
- No sediments from river
depositing at the coast
(eg.Christiansen, 2002)
• Coastal driving forces:
- Eustatic sea level change (1mm/yr)
by Harff and Lüth (2007)
- Vertical crustal movement
(0 to - 0.5mm/yr)
by Harff and Meyer (2011)
- Wind (wave, storm surge)
15m*15m Recent DEM (UTM 33N)
The purpose to develop new method
• Forward modeling: long term morphodynamic model ( BS-
LTMM) (Zhang et al., 2010ab, 2011, 2012a)
Forward model (BS-LTMM)
Parameterization Prediction(projection)
Validation
DEM1900 AD DEM2000 AD DEM2100 AD
Model
Inverse model Measured Data
Iteration parameter Eustatic sea level
change
DEM1900 AD Model DEM2000 AD Local neotetonic
movement
Sediment
budget analysis Historical map at
1900 AD
Dynamic equilibrium shore model
• Classic Bruun model (Bruun, 1964; 1988) for the retreating
cliff coast by definition of Wolinsky and Murray (2009)
• Submarine profile shape is invariant
• There are no external sediment sources or sinks
• Profile shifts with the same displacement of sea level rise and
coastline retreat
• Dynamic equilibrium shore model
• Submarine profile shape is variable
• There are external sediment sources or sinks
• Profile shifts with the same displacement of sea level rise and
coastline retreat
• The submarine profile shape is approximated by exponential function presented by
(Bodge,1992; Komar and Mcdougal, 1994; Romanczyk et al., 2005), as the limit of
exponential decay might be related to limit of offshore decay of sediment movement,
which is in contrast to the infinite depth of the power law function by Dean (1991)
What’s Dynamic equilibrium shore model ?
Where
Offshore limit of
exponential function
b0 and b1 are
Curvature parameter
0
For the whole retreating coast
Unknown: Because b1 is unknown
Assume: b1=b0
Known:
Numerical process for calculating b1
Inverse modeling Const = 1.0
Const =
b1= b0* const
Const - 0.1
Dynamic equilibrium
shore model
Input
Vexternal > Bathymetrical mass volume
∑(Verosion-Vdeposition) internal
Historical coastline at ca. 1900 AD
(1 : 25 000 Messtischblatt map)
Recent coastline at ca. 2000 AD
From topographic map at the Usedom
Island , and high resolution profiles at
the Wolin island (Maritime Office in
Szczecin)Coastline change(m)
Coastline change (c) for the last 100 years
Recent DEM (UTM33N) and cross shore base lines for the modelingSubaerial sediment mass volume (Vdune)subaerial, Vcliff )
Inverse procedure (Submarine sediment mass volume from b1 = 1.0 b0 to b1= 0.7*b0)
(Vdune)submarine, ∑(Verosion-Vdeposition) internalb1 = 0.7 b0 Paleo-DEM at 1900 AD b1 = b 0
Recent DEM at 2000 AD
• Forward modeling: long term morphodynamic model ( BS-LTMM)
(Zhang et al., 2010ab,2011, 2012a)
Wind, Sea level change and Glacial Isostatic Adjustment movement
Process-based model (BS-LTMM)
Parameterization
Validation
DEM1900 AD Predicted DEM2000 AD
Coastline change
Comparison in
Sediment erosion and deposition
DEM1900 AD Measured DEM2000 AD
Inverse model: Dynamic equilibrium shore model
Sea level change and Neotectonic movementsBS-LTMM model input:
Paleo-DEM Geological Glacial Isostatic
Representative wind Eustatic curve
at ca. 1900 AD map AdjustmentBS-LTMM model input:
Paleo-DEM Geological Glacial Isostatic
Representative wind Eustatic curve
at ca. 1900 AD map Adjustment
Wind data from well validated coupled atmosphere and ocean model by Weisse et al, 2009BS-LTMM model input:
Paleo-DEM Geological Glacial Isostatic
Representative wind Eustatic curve
at ca. 1900 AD map Adjustment
Surface sediment map modified from Bobertz et al. (2006)BS-LTMM model input:
Paleo-DEM Geological Glacial Isostatic
Representative wind Eustatic curve
at ca. 1900 AD map Adjustment
Climatically controlled sea level rise, southern Baltic for the last 8.000 years
(rsl-curve Fischland after Lampe et al., 2007)BS-LTMM model input:
Paleo-DEM Geological Glacial Isostatic
Representative wind Eustatic curve
at ca. 1900 AD map Adjustment
(mm) Dudzinska-Nowak et al. (in prep.)Coastline change comparison between modeled and measured
(a) Difference between Measured DEM 2000 AD and
reconstructed DEM at 1900 AD
Deposition
(b) Simulated bed level Changes by BS-LTMM From
1900 AD to 2000 AD
ErosionSummary and Discussion
• This work shows that the reconstruction method based on the Dynamic
equilibrium shore model and inverse modeling technique results in a paleo-
DEM that serves as a sufficient base for the hindcast simulation of BS-LTMM
by the comparison
• in coastline change
• and sediment erosion and deposition.
• The inverse procedure proves that the paleo-profile shape along the cliff
coast is different from the recent one with a smaller curvature parameter.
• the sea floor abrasion take places further offshore to the depth deeper
then 11m, this coincides with the results by Schwarzer et al. (2003)
• The inverse modeling is an effective method to determine the unknown
parameters, when the variant profile shape is assumed.
• Despite the fact that the Dynamic equilibrium shore model is simplifying the
multi-scale process of coastal morphodynamics, it has the potential to be
used in coastal protection planning, for instance for balancing beach
nourishments.The prospects for the reconstruction of Paleo-
DEM at ca. 1500 AD of Swina gate
• Coastline reconstruction at ca. 1500 AD based on
• OSL dating from Reimann et al. (2011)
• High resolution (15m*15m) DEM of Swina gate area
Fig. 6 Maps showing the ages of the yellow and white dunes at Wolin spit. OSL ages are indicated in ka before 2008, and
radiocarbon ages are indicated in calibrated ka BP.The prospects for the reconstruction of Paleo-
DEM at ca. 1500 AD of Swina gate
• Coastline reconstruction at ca. 1500 AD
Reeve and Spivack (1994)The prospects for the reconstruction of Paleo- DEM at ca. 1500 AD of Swina gate • Coastline reconstruction at ca. 1500 AD based on • High resolution (15m*15m) DEM of Swina gate area
Acknowledgement • Thanks to the CoPaF (www.copaf.pl) project funded by Ministry of Science and Higher Education in Poland for the research. • Thanks to the co-workers in Szczecin University, Poland and Greifswald University, Germany
Model Description (BS-LTMM) (Zhang et al., 2010ab, 2011, 2012a)
Generalize Bruun model
Unknown:
Because b1 is unknown
Assume: b1=b0
Known:You can also read
