Model:CEM: Difference between revisions
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|Phone=919 681-5069 | |Phone=919 681-5069 | ||
|Fax=919 684-5833 | |Fax=919 684-5833 | ||
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{{Model identity | {{Model identity | ||
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|One-line model description=Coastline evolution model | |One-line model description=Coastline evolution model | ||
|Extended model description=The Coastline Evolution Model (CEM) addresses predominately sandy, wave-dominated coastlines on time-scales ranging from years to millenia and on spatial scales ranging from kilometers to hundreds of kilometers. Shoreline evolution results from gradients in wave-driven alongshore sediment transport. At its most basic level, the model follows the standard 'one-line' modeling approach, where the cross-shore dimension is collapsed into a single data point. However, the model allows the plan-view shoreline to take on arbitrary local orientations, and even fold back upon itself, as complex shapes such as capes and spits form under some wave climates (distributions of wave influences from different approach angles). The model can also represent the geology underlying the sandy coastline and shoreface in a simplified manner and enables the simulation of coastline evolution when sediment supply from an eroding shoreface may be constrained. CEM also supports the simulation of human manipulations to coastline evolution through beach nourishment or hard structures. | |Extended model description=The Coastline Evolution Model (CEM) addresses predominately sandy, wave-dominated coastlines on time-scales ranging from years to millenia and on spatial scales ranging from kilometers to hundreds of kilometers. Shoreline evolution results from gradients in wave-driven alongshore sediment transport. At its most basic level, the model follows the standard 'one-line' modeling approach, where the cross-shore dimension is collapsed into a single data point. However, the model allows the plan-view shoreline to take on arbitrary local orientations, and even fold back upon itself, as complex shapes such as capes and spits form under some wave climates (distributions of wave influences from different approach angles). The model can also represent the geology underlying the sandy coastline and shoreface in a simplified manner and enables the simulation of coastline evolution when sediment supply from an eroding shoreface may be constrained. CEM also supports the simulation of human manipulations to coastline evolution through beach nourishment or hard structures. | ||
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{{Start model keyword table | {{Start model keyword table | ||
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{{Model keywords | {{Model keywords | ||
|Model keywords=coastal evolution | |Model keywords=coastal evolution | ||
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{{End a table | {{End a table | ||
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{{Model technical information | {{Model technical information | ||
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|Memory requirements=20 Mb | |Memory requirements=20 Mb | ||
|Typical run time=days | |Typical run time=days | ||
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{{Input - Output description | {{Input - Output description | ||
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|If above answer is yes=Matlab | |If above answer is yes=Matlab | ||
|Other visualization software=Note: if using the JPEGs automatically generated, the answer to the visualization question is 'no.' | |Other visualization software=Note: if using the JPEGs automatically generated, the answer to the visualization question is 'no.' | ||
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{{Process description model | {{Process description model | ||
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|Describe time scale and resolution constraints=Years to millenia. Typically, the model is run with timesteps on the order of a day. However, the assumptions that the shoreface progrades or erodes while maintaining its cross-shore shape prevents model results from being interpreted as meaningful over time scales shorter than years to decades. (Storm and post storm cross-shore shifting of sediment within the shoreface causes shoreline fluctuations on event timescales that are implicitly averaged out in this model.) | |Describe time scale and resolution constraints=Years to millenia. Typically, the model is run with timesteps on the order of a day. However, the assumptions that the shoreface progrades or erodes while maintaining its cross-shore shape prevents model results from being interpreted as meaningful over time scales shorter than years to decades. (Storm and post storm cross-shore shifting of sediment within the shoreface causes shoreline fluctuations on event timescales that are implicitly averaged out in this model.) | ||
|Describe any numerical limitations and issues=The model handles complex-shaped coastlines, such as cuspate-capes and spits. However, where the shoreline curvature becomes extreme (radius of curvature comparable to the cross-shore shoreface extent), as at the ends of spits, the assumptions of a locally rectilinear coordinate system break down, and sediment is conserved less rigorously locally. See Ashton and Murray (2006a) for details. | |Describe any numerical limitations and issues=The model handles complex-shaped coastlines, such as cuspate-capes and spits. However, where the shoreline curvature becomes extreme (radius of curvature comparable to the cross-shore shoreface extent), as at the ends of spits, the assumptions of a locally rectilinear coordinate system break down, and sediment is conserved less rigorously locally. See Ashton and Murray (2006a) for details. | ||
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{{Model testing | {{Model testing | ||
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However, to date the model has been used chiefly for relatively abstract explorations of how coastline evolution works: how emergent coastline structures such as capes, spits, and alongshore sand waves form and interact; how heterogeneity in underlying geology affects coastline evolution; how scenarios of changing storm and wave climates would affect coastline change; and how human manipulations alter large-scale coastline change). Ashton and Murray (2006b) compared robust model predictions concerning the way local wave climates vary along a coastline with emergent structures (capes and flying spits) to hindcast wave climates along actual shorelines. As opposed to testing whether model parameters can be adjusted to reproduce observations in detail, testing a robust prediction like this, which does not depend on the formal details of the model ingredients, can falsify the hypothesis that the interactions in the model capture the basic aspects of the interactions that are important in the actual system (see Murray, 2003; 2007). | However, to date the model has been used chiefly for relatively abstract explorations of how coastline evolution works: how emergent coastline structures such as capes, spits, and alongshore sand waves form and interact; how heterogeneity in underlying geology affects coastline evolution; how scenarios of changing storm and wave climates would affect coastline change; and how human manipulations alter large-scale coastline change). Ashton and Murray (2006b) compared robust model predictions concerning the way local wave climates vary along a coastline with emergent structures (capes and flying spits) to hindcast wave climates along actual shorelines. As opposed to testing whether model parameters can be adjusted to reproduce observations in detail, testing a robust prediction like this, which does not depend on the formal details of the model ingredients, can falsify the hypothesis that the interactions in the model capture the basic aspects of the interactions that are important in the actual system (see Murray, 2003; 2007). | ||
|Describe ideal data for testing=See answer above and Ashton and Murray (2006a, b). Data sets spanning large spatial scales are most appropriate, and if model behaviors are going to be compared to shoreline change, long temporal scales are best (see ‘limitations’ above). | |Describe ideal data for testing=See answer above and Ashton and Murray (2006a, b). Data sets spanning large spatial scales are most appropriate, and if model behaviors are going to be compared to shoreline change, long temporal scales are best (see ‘limitations’ above). | ||
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{{Users groups model | {{Users groups model | ||
|Do you have current or future plans for collaborating with other researchers?=Collaborations are underway within Duke University (an interdisciplinary project involving human shoreline manipulations) and Woods Hole Oceanographic Institution (where the model is being used to explore delta dynamics). Various collaborations involving researchers in the US and abroad are in various stages. | |Do you have current or future plans for collaborating with other researchers?=Collaborations are underway within Duke University (an interdisciplinary project involving human shoreline manipulations) and Woods Hole Oceanographic Institution (where the model is being used to explore delta dynamics). Various collaborations involving researchers in the US and abroad are in various stages. | ||
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{{Documentation model | {{Documentation model | ||
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* Murray, A.B., 2003, Contrasting the goal, strategies, and predictions associated with simplified numerical models and detailed simulations, in Prediction in Geomorphology, Dick Iverson and Peter Wilcock Eds, Geophysical Monograph 135, American Geophysical Union, 151-165. | * Murray, A.B., 2003, Contrasting the goal, strategies, and predictions associated with simplified numerical models and detailed simulations, in Prediction in Geomorphology, Dick Iverson and Peter Wilcock Eds, Geophysical Monograph 135, American Geophysical Union, 151-165. | ||
|Manual model available=No | |Manual model available=No | ||
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{{Additional comments model | {{Additional comments model | ||
|Comments=This entry, with the name 'Coastline Evolution Model' should replace the 'Murray model' currently listed. Thanks Albert! | |Comments=This entry, with the name 'Coastline Evolution Model' should replace the 'Murray model' currently listed. Thanks Albert! | ||
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{{CSDMS staff part | {{CSDMS staff part | ||
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|IRF interface=Yes | |IRF interface=Yes | ||
|CMT component=Yes | |CMT component=Yes | ||
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{{Start coupled table | {{Start coupled table | ||
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{{CSDMS coupled models | {{CSDMS coupled models | ||
|Animation model name=Avulsion | |Animation model name=Avulsion | ||
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{{End a table | {{End a table | ||
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{{End headertab | {{End headertab | ||
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