Model help:CEM: Difference between revisions
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1) Log in to the wiki | 1) Log in to the wiki | ||
2) Create a new page for each model, by using the following URL: | 2) Create a new page for each model, by using the following URL: | ||
* | * https://csdms.colorado.edu/wiki/Model help:<modelname> | ||
* Replace <modelname> with the name of a model from Gary | * Replace <modelname> with the name of a model from Gary | ||
3) Than follow the link "edit this page" | 3) Than follow the link "edit this page" | ||
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{{Model_help_image}} | {{Model_help_image}} | ||
__NOTOC__ | __NOTOC__ | ||
={{PAGENAME}} | <div id="CMT_MODEL_MEMO"> | ||
==<big><big>{{PAGENAME}}</big></big>== | |||
The CEM model, the Coastline Evolution Model, simulates the evolution of a shoreline due to gradients in breaking-wave-driven alongshore sediment transport. The original CEM has been componentized to consist of the longshore transport module (CEM) and a wave input module [[Model_help:Waves|(WAVES)]]. | |||
The CEM model, the Coastline Evolution Model, simulates the evolution of a shoreline due to gradients in breaking-wave-driven alongshore sediment transport. The original CEM has been componentized to consist of the | </div> | ||
<div id="CMT_MODEL_DESC"> | |||
==Extended model introduction== | ==Extended model introduction== | ||
The CEM model assumes that the coast consists of a high percentage of mobile sediment and its other assumptions are more applicable at shoreline lengths of km’s and larger. The model was initially designed to investigate an instability in the shape of the coast caused by waves approaching with ‘high’ angles (with the angle between | The CEM model assumes that the coast consists of a high percentage of mobile sediment and its other assumptions are more applicable at shoreline lengths of km’s and larger. The model was initially designed to investigate an instability in the shape of the coast caused by waves approaching with ‘high’ angles (with the angle between offshore wave crests--i.e. before transformation over approximately shore-parallel contours--and the coast > 45 degrees). <br> | ||
Although a number of wave (and geometry) parameters can be entered, the most vital input control for CEM is the wave climate. The current version of the CEM is driven by simplified directional wave climate controlled by two main input parameters: the asymmetry of the incoming waves angle and the proportion of high-angle waves. This model is not designed to accurately simulate a specific geographic location in detail but rather to more generally represent how a shoreline with highly mobile sediment may respond to varying wave angles. The value in this model is in the breadth it offers in representing how different wave climates can result in different potentially interesting shoreline configurations. Ashton and Murray (2006b) present a more thorough description of the model parameters and theoretical underpinning. | Although a number of wave (and geometry) parameters can be entered, the most vital input control for CEM is the wave climate. The current version of the CEM is driven by simplified directional wave climate controlled by two main input parameters: the asymmetry of the incoming waves angle and the proportion of high-angle waves. This model is not designed to accurately simulate a specific geographic location in detail but rather to more generally represent how a shoreline with highly mobile sediment may respond to varying wave angles. The value in this model is in the breadth it offers in representing how different wave climates can result in different potentially interesting shoreline configurations. Ashton and Murray (2006b) present a more thorough description of the model parameters and theoretical underpinning. | ||
</div> | |||
= | <div id="CMT_MODEL_HELP"> | ||
==Model parameters== | |||
CEM does not need input files from the user, its input is entirely specified in the CMT graphical user interface. | |||
|= | To obtain output from this component make sure you toggle on the output files; as a default they are OFF. | ||
| | |||
= Input Files and directories = | |||
{|{{Prettytable}} class = "wikitable unsortable" cellspacing="0" cellpadding="0" style="margin:0em 0em 0em 0;" | |||
|- | |||
!Parameter!!Description!!Unit | |||
|- | |- | ||
| | |width="20%"| Site prefix | ||
|= | |width="60%"| Part of the input and output file name e.g. the name of the location, or project | ||
|[-] | |width="20%"| [-] | ||
|- | |- | ||
| | | Case prefix | ||
| | | Part of the input and output file name that provides you the opportunity to do different scenario simulations for e.g. the same location, or project | ||
|[ | | [-] | ||
|} | |||
=Run Parameters= | |||
{|{{Prettytable}} class = "wikitable unsortable" cellspacing="0" cellpadding="0" style="margin:0em 0em 0em 0;" | |||
|- | |- | ||
| | !Parameter!!Description!!Unit | ||
|= Longitudinal Slope of the Shelf | |-valign="top" | ||
|[-] | |width="20%"| Run duration | ||
|width="60%"| Number of simulation time steps | |||
|width="20%"| [days] | |||
|-valign="top" | |||
| Shoreface slope | |||
| Longitudinal Slope of the Shoreface | |||
| [-] | |||
|-valign="top" | |||
| Shoreface depth | |||
| Critical threshold depth defining the shoreface | |||
| [m] | |||
|-valign="top" | |||
| Shelf slope | |||
| Longitudinal Slope of the Shelf | |||
| [-] | |||
|- | |- | ||
|} | |||
=Grid= | |||
{|{{Prettytable}} class = "wikitable unsortable" cellspacing="0" cellpadding="0" style="margin:0em 0em 0em 0;" | |||
|- | |||
!Parameter!!Description!!Unit | |||
|-valign="top" | |||
|width="20%"| Number of grid rows | |||
|width="60%"| number of rows in the computational grid | |||
|width="20%"| [-] | |||
|-valign="top" | |||
| Number of grid columns | |||
| number of columns in the computational grid | |||
| [-] | |||
|-valign="top" | |||
| Spacing of grid rows | |||
| spaces of rows in the computational grid | |||
| [m] | |||
|-valign="top" | |||
| Spacing of grid columns | |||
| spaces of columns in the computational grid | |||
| [-] | |||
|- | |||
|} | |} | ||
== | =Output Grids= | ||
{|{{Prettytable}} class = "wikitable unsortable" cellspacing="0" cellpadding="0" style="margin:0em 0em 0em 0;" | |||
{| | |||
|- | |- | ||
| | !Parameter!!Description!!Unit | ||
|= | |-valign="top" | ||
|[%] | |width="20%"| Output directory | ||
|width="60%"| path to output grid files | |||
|width="20%"| [-] | |||
|-valign="top" | |||
| Interval between output files | |||
| Specify how often you want output to be written; ''Notice: files will be really large if you choose to save every timestep''. | |||
| [-] | |||
|-valign="top" | |||
| Depth file | |||
| Evolving land and ocean bottom grid | |||
| [m, grid-stacks in NetCDF format] | |||
|-valign="top" | |||
| Percent_filled file | |||
| Records the fill of the individual cells for the entire grid. | |||
| [%, grid-stacks in NetCDF format] | |||
|- | |- | ||
|} | |} | ||
<headertabs/> | |||
==Coupling parameters== | ==Coupling parameters== | ||
===Uses ports=== | ===Uses ports=== | ||
< | CEM requires wave parameters as supplied by the WAVES component.[[Model_help:Waves|(Model Help of WAVES)]].<br> | ||
CEM requires a sediment flux (bedload) originating from one or more river distributary channels. This is provided by the AVULSION component. | |||
===Provides ports=== | ===Provides ports=== | ||
< | CEM provides an elevation grid of offshore geometry after erosion and deposition is done in every timestep.<br> | ||
The elevation is required for the AVULSION component. | |||
==Main equations== | ==Main equations== | ||
< | * Alongshore sediment transport | ||
::::{| | |||
=== | |width=800px|<math>Q_{s} = K_{2} H_{0} ^ \left ( {\frac{12}{5}} \right ) T ^ \left ( {\frac{12}{5}} \right ) cos ^ \left ( {\frac{6}{5}}\right ) \left ( \Phi _{0} - \theta \right ) sin \left ( \Psi _{0} - \theta \right )</math> | ||
< | |width=50px align="right"|(1) | ||
|} | |||
::::{| | |||
|width=800px|<math>K_{2} = \left ( {\frac{\sqrt{g \gamma}}{2 \pi}}\right ) ^ \left ({\frac{1}{5}} \right ) K_{1} </math> | |||
|width=50px align="right"|(2) | |||
|} | |||
* Predictions of shoreline evolution | |||
::::{| | |||
|width=800px|<math>{\frac{d \eta}{d t}} = - {\frac{K_{1}}{D_{sf}}} H_{b} ^ \left ({\frac{5}{2}} \right ) {\frac{d^2 \eta}{d x^2}} </math> | |||
|width=50px align="right"|(3) | |||
|} | |||
::::{| | |||
|width=800px|<math>cos^ \left ( {\frac{1}{3}}\right ) \left ( \Phi_{b} - \theta \right ) \approx 1 </math> | |||
|width=50px align="right"|(4) | |||
|} | |||
* Alongshore component of the radiation stress | |||
::::{| | |||
|width=800px|<math>S_{xy} = H^2 sin \left ( \Phi - \theta \right ) cos \left ( \Phi - \theta \right ) </math> | |||
|width=50px align="right"|(5) | |||
|} | |||
* Shoreline instability | |||
::::{| | |||
|width=800px|<math>{\frac{d \eta}{d t}} = - {\frac{K_{2}}{D}} H_{0} ^ \left ({\frac{12}{5}} \right ) T^ \left ( {\frac{1}{5}} \right ) \{cos^\left ( {\frac{1}{5}} \right ) \left ( \Phi_{0} - \theta \right ) [ cos^2 \left ( \Phi _{0} - \theta \right ) - \left ( {\frac{6}{5}} \right ) sin^2 \left ( \Phi_{0} - \theta \right )] \} {\frac{d^2 \eta}{d x^2}} </math> | |||
|width=50px align="right"|(6) | |||
|} | |||
* Shoreline adjustment | |||
::::{| | |||
|width=800px|<math>\Delta F = {\frac{\left ( Q_{in} - Q_{out} \right )}{\left ( D_{sf} + B \right ) \Delta W^2}} </math> | |||
|width=50px align="right"|(7) | |||
|} | |||
::::{| | |||
|width=800px|<math>\Delta t \propto \left ( {\frac{K_{1}}{D_{sf}}} H_{0} ^ \left ({\frac{12}{5}} \right ) T^\left ( {\frac{1}{5}}\right ) \right ) \Delta x^2 </math> | |||
|width=50px align="right"|(8) | |||
|} | |||
::::{| | |||
|width=800px|<math>\Delta Y_{bb} = {\frac{\left ( D_{sf} + B \right ) }{\left ( D_{bb} + B \right )}}\Delta Y_{sl} </math> | |||
|width=50px align="right"|(9) | |||
|} | |||
::::{| | |||
|width=800px|<math>W_{c} = W_{0} + \Delta Y_{bb} - \Delta Y_{sl} </math> | |||
|width=50px align="right"|(10) | |||
|} | |||
::::{| | |||
|width=800px|<math>\Delta Y_{bb} = {\frac{\left ( W_{c} - W_{0} \right )}{\left ( 1 - {\frac{\left ( D_{bb} + B \right ) }{\left (D_{sf} + B \right )}} \right )}} </math> | |||
|width=50px align="right"|(11) | |||
|} | |||
::::{| | |||
|width=800px|<math> \Delta Y_{sl} = {\frac{\left ( W_{c} - W_{0}\right )}{\left ({\frac{\left ( D_{sf} + B \right ) }{\left ( D_{bb} + B \right ) } - 1} \right )}} </math> | |||
|width=50px align="right"|(12) | |||
|} | |||
==Notes== | ==Notes== | ||
The parameters: '''Shoreface Slope''', '''Shoreface Depth''' and '''Shelf Slope''' set the initial geometry of the shoreface domain and the shelf domain. Simulations will use the shoreface depth as an effective erosion depth, but deposition can take place to deeper depths if the shoreface is accreting on a deeper shelf. | |||
==Examples== | ==Examples== | ||
Line 83: | Line 186: | ||
<span style="color:gray">''Follow the next steps to include images / movies of simulations:''</span> | <span style="color:gray">''Follow the next steps to include images / movies of simulations:''</span> | ||
* <span style="color:gray">''Upload file: | * <span style="color:gray">''Upload file: https://csdms.colorado.edu/wiki/Special:Upload''</span> | ||
* <span style="color:gray">''Create link to the file on your page: <nowiki>[[Image:<file name>]]</nowiki>.</span> | * <span style="color:gray">''Create link to the file on your page: <nowiki>[[Image:<file name>]]</nowiki>''.</span> | ||
<span style="color:gray">''See also: [[Help:Images]] or [[Help:Movies]]''</span> | <span style="color:gray">''See also: [[Help:Images]] or [[Help:Movies]]''</span> | ||
==Developer(s)== | ==Developer(s)== | ||
Andrew Ashton | [[User:AAshton|Andrew Ashton]] | ||
==References== | ==References== | ||
Ashton A., Murray B.A. Arnault O. Formation of Coastline Features by Large-Scale Instabilities Induced by High-Angle Waves. Nature Magazine. Volume 414. 15 November 2001 <br> | * Ashton A., Murray B.A. Arnault O. Formation of Coastline Features by Large-Scale Instabilities Induced by High-Angle Waves. Nature Magazine. Volume 414. 15 November 2001 <br> | ||
Ashton A.D., Murray A.B. High-Angle Wave Instability and Emergent Shoreline Shapes: 1. Wave Climate Analysis and Comparisons to Nature. Journal of Geophysical Research. Volume 111. 15 December 2006.<br> | * Ashton A.D., Murray A.B. High-Angle Wave Instability and Emergent Shoreline Shapes: 1. Wave Climate Analysis and Comparisons to Nature. Journal of Geophysical Research. Volume 111. 15 December 2006.<br> | ||
Ashton A.D., Murray A.B. High-Angle Wave Instability and Emergent Shoreline Shapes: 2. Wave Climate Analysis and Comparisons to Nature. Journal of Geophysical Research. Volume 111. 15 December 2006.<br> | * Ashton A.D., Murray A.B. High-Angle Wave Instability and Emergent Shoreline Shapes: 2. Wave Climate Analysis and Comparisons to Nature. Journal of Geophysical Research. Volume 111. 15 December 2006.<br> | ||
== | ==Links== | ||
Movies generated with the stand-alone CEM model are documented in the CSDMS movie gallery. | Movies generated with the stand-alone CEM model are documented in the CSDMS movie gallery. | ||
https://csdms.colorado.edu/wiki/Coastal_animations | |||
</div> | |||
[[Category:Modules]] | [[Category:Modules]] |
Latest revision as of 17:19, 19 February 2018
CEM
The CEM model, the Coastline Evolution Model, simulates the evolution of a shoreline due to gradients in breaking-wave-driven alongshore sediment transport. The original CEM has been componentized to consist of the longshore transport module (CEM) and a wave input module (WAVES).
Extended model introduction
The CEM model assumes that the coast consists of a high percentage of mobile sediment and its other assumptions are more applicable at shoreline lengths of km’s and larger. The model was initially designed to investigate an instability in the shape of the coast caused by waves approaching with ‘high’ angles (with the angle between offshore wave crests--i.e. before transformation over approximately shore-parallel contours--and the coast > 45 degrees).
Although a number of wave (and geometry) parameters can be entered, the most vital input control for CEM is the wave climate. The current version of the CEM is driven by simplified directional wave climate controlled by two main input parameters: the asymmetry of the incoming waves angle and the proportion of high-angle waves. This model is not designed to accurately simulate a specific geographic location in detail but rather to more generally represent how a shoreline with highly mobile sediment may respond to varying wave angles. The value in this model is in the breadth it offers in representing how different wave climates can result in different potentially interesting shoreline configurations. Ashton and Murray (2006b) present a more thorough description of the model parameters and theoretical underpinning.
Model parameters
CEM does not need input files from the user, its input is entirely specified in the CMT graphical user interface. To obtain output from this component make sure you toggle on the output files; as a default they are OFF.
Coupling parameters
Uses ports
CEM requires wave parameters as supplied by the WAVES component.(Model Help of WAVES).
CEM requires a sediment flux (bedload) originating from one or more river distributary channels. This is provided by the AVULSION component.
Provides ports
CEM provides an elevation grid of offshore geometry after erosion and deposition is done in every timestep.
The elevation is required for the AVULSION component.
Main equations
- Alongshore sediment transport
[math]\displaystyle{ Q_{s} = K_{2} H_{0} ^ \left ( {\frac{12}{5}} \right ) T ^ \left ( {\frac{12}{5}} \right ) cos ^ \left ( {\frac{6}{5}}\right ) \left ( \Phi _{0} - \theta \right ) sin \left ( \Psi _{0} - \theta \right ) }[/math] (1)
[math]\displaystyle{ K_{2} = \left ( {\frac{\sqrt{g \gamma}}{2 \pi}}\right ) ^ \left ({\frac{1}{5}} \right ) K_{1} }[/math] (2)
- Predictions of shoreline evolution
[math]\displaystyle{ {\frac{d \eta}{d t}} = - {\frac{K_{1}}{D_{sf}}} H_{b} ^ \left ({\frac{5}{2}} \right ) {\frac{d^2 \eta}{d x^2}} }[/math] (3)
[math]\displaystyle{ cos^ \left ( {\frac{1}{3}}\right ) \left ( \Phi_{b} - \theta \right ) \approx 1 }[/math] (4)
- Alongshore component of the radiation stress
[math]\displaystyle{ S_{xy} = H^2 sin \left ( \Phi - \theta \right ) cos \left ( \Phi - \theta \right ) }[/math] (5)
- Shoreline instability
[math]\displaystyle{ {\frac{d \eta}{d t}} = - {\frac{K_{2}}{D}} H_{0} ^ \left ({\frac{12}{5}} \right ) T^ \left ( {\frac{1}{5}} \right ) \{cos^\left ( {\frac{1}{5}} \right ) \left ( \Phi_{0} - \theta \right ) [ cos^2 \left ( \Phi _{0} - \theta \right ) - \left ( {\frac{6}{5}} \right ) sin^2 \left ( \Phi_{0} - \theta \right )] \} {\frac{d^2 \eta}{d x^2}} }[/math] (6)
- Shoreline adjustment
[math]\displaystyle{ \Delta F = {\frac{\left ( Q_{in} - Q_{out} \right )}{\left ( D_{sf} + B \right ) \Delta W^2}} }[/math] (7)
[math]\displaystyle{ \Delta t \propto \left ( {\frac{K_{1}}{D_{sf}}} H_{0} ^ \left ({\frac{12}{5}} \right ) T^\left ( {\frac{1}{5}}\right ) \right ) \Delta x^2 }[/math] (8)
[math]\displaystyle{ \Delta Y_{bb} = {\frac{\left ( D_{sf} + B \right ) }{\left ( D_{bb} + B \right )}}\Delta Y_{sl} }[/math] (9)
[math]\displaystyle{ W_{c} = W_{0} + \Delta Y_{bb} - \Delta Y_{sl} }[/math] (10)
[math]\displaystyle{ \Delta Y_{bb} = {\frac{\left ( W_{c} - W_{0} \right )}{\left ( 1 - {\frac{\left ( D_{bb} + B \right ) }{\left (D_{sf} + B \right )}} \right )}} }[/math] (11)
[math]\displaystyle{ \Delta Y_{sl} = {\frac{\left ( W_{c} - W_{0}\right )}{\left ({\frac{\left ( D_{sf} + B \right ) }{\left ( D_{bb} + B \right ) } - 1} \right )}} }[/math] (12)
Notes
The parameters: Shoreface Slope, Shoreface Depth and Shelf Slope set the initial geometry of the shoreface domain and the shelf domain. Simulations will use the shoreface depth as an effective erosion depth, but deposition can take place to deeper depths if the shoreface is accreting on a deeper shelf.
Examples
An example run with input parameters as well as a figure / movie of the output
Follow the next steps to include images / movies of simulations:
- Upload file: https://csdms.colorado.edu/wiki/Special:Upload
- Create link to the file on your page: [[Image:<file name>]].
See also: Help:Images or Help:Movies
Developer(s)
References
- Ashton A., Murray B.A. Arnault O. Formation of Coastline Features by Large-Scale Instabilities Induced by High-Angle Waves. Nature Magazine. Volume 414. 15 November 2001
- Ashton A.D., Murray A.B. High-Angle Wave Instability and Emergent Shoreline Shapes: 1. Wave Climate Analysis and Comparisons to Nature. Journal of Geophysical Research. Volume 111. 15 December 2006.
- Ashton A.D., Murray A.B. High-Angle Wave Instability and Emergent Shoreline Shapes: 2. Wave Climate Analysis and Comparisons to Nature. Journal of Geophysical Research. Volume 111. 15 December 2006.
Links
Movies generated with the stand-alone CEM model are documented in the CSDMS movie gallery. https://csdms.colorado.edu/wiki/Coastal_animations