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Woods Hole +
This entry, with the name 'Coastline Evolution Model' should replace the 'Murray model' currently listed. Thanks Albert! +
United States +
Andrew +
WHOI +
Ashton +
260 Woods Hole Rd MS 22 +
02543 +
Massachusetts +
Model developer +
Yes +
No but planned +
Single Processor +
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17:30:29, 20 February 2009 +
Collaborations are underway within Duke Un … 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.n the US and abroad are in various stages. +
https://csdms.colorado.edu/pub/models/doi-source-code/cem-10.1594.IEDA.100100-0.1.tar.gz +
In one application, the rate of change in … In one application, the rate of change in the model has been calibrated to a state data set averaging shoreline change over 50 years (from the North Carolina Department of Transportation; see Slott et al., 2007). Numerous other shoreline change data sets are available, based on surveys of various sorts, aerial photography, and recently LIDAR (e.g. Lazarus and Murray, 2007).tly LIDAR (e.g. Lazarus and Murray, 2007). +
See answer above; many shoreline data sets … See answer above; many shoreline data sets exist. Comparing model results to detailed records of coastline change will become more appropriate as the model is used to investigate shoreline change in more detail in a particular location and time period.</br></br>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).he actual system (see Murray, 2003; 2007). +
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). +
The input parameters to a model run consis … The input parameters to a model run consist of an initial shoreline, a wave file, and a set of configuration parameters. The initial shoreline is stored within a custom binary formatted-file. Since CEM has been used for abstract simulations of coastline evolution, the initial model condition consists either of a mostly-smooth shoreline with initial perturbations to the shoreline position (generated by a tool provided with the model), or using a shoreline that resulted from a previous model run. The wave file consists of a set of wave approach angles and wave heights that are used during the model run. This wave file is also generated by a tool provided with the model, and takes as input the statistical distribution of wave-approach angles. Finally, basic model parameters (e.g. number of time steps to simulate, etc.) are specified within an XML-formatted text file. An example is provided with the model.le. An example is provided with the model. +
The evolution of the coastline is governed … The evolution of the coastline is governed by a continuity equation; the rate of horizontal shoreline change in the local cross-shore direction is proportional to the divergence of alongshore sediment flux. Alongshore sediment transport is computed via the common CERC formula, which relates alongshore sediment flux to breaking-wave approach angle and breaking wave height. Breaking-wave characteristics in each shoreline location are calculated by starting with the deep-water height and propagation direction (obtained for each time slice from the input wave file), and refracting and shoaling the waves over assumed shore-parallel contours until breaking occurs. The CERC equation also involves an empirical constant K, which can be configured by the model user. Other equations for sediment flux can easily be substituted. See Ashton and Murray (2006a) for details.See Ashton and Murray (2006a) for details. +
Kilometers to hundreds of kilometers. Numerically, the model can be discretized with much smaller spatial resolution. However, the assumptions of approximately shore-parallel shoreface contours becomes unreasonable at scales smaller than kilometers. +
The model handles complex-shaped coastline … 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.See Ashton and Murray (2006a) for details. +
The output of the model consists of snapsh … The output of the model consists of snapshots of the coastline during its evolution. The model can be configured to write the resulting coastline at any point during the simulation. The output format of the coastline file is a custom binary formatted-file (the same format as the initial model input). Also, for convenience using with other software tools such as MATLAB, an ASCII-based file of the coastline shape can be written too. The model can also directly generate JPEG-formatted pictures of the coastline shape at any time during the simulation.e shape at any time during the simulation. +
Post-processing software is sometimes nece … Post-processing software is sometimes necessary: In some instances (if not just using the JPEGs generated by the model code), some post-processing of the results is desired, e.g. to compare the position of the shoreline between two different times. The model code comes with simple tools to perform simple post-processing. The model also outputs the shoreline in an ASCII format and further post-processing may be achieved using tools such as MATLAB.ay be achieved using tools such as MATLAB. +
A continuity equation, representing the co … A continuity equation, representing the conservation of sediment in the nearshore zone, relates gradients in alongshore sediment flux to horizontal shoreline changes, given a depth over which erosion or accretion are distributed—the depth of the shoreface. This treatment embodies the assumption that cross-shore sediment fluxes across base of the shoreface are small compared to gradients in alongshore flux. However, cross-shore sediment fluxes landward of the shoreline, associated with overwash, are treated, allowing barriers to migrate and maintain elevation relative to a rising sea level. See Ashton and Murray (2006a) for a full treatment of these model dynamics.</br></br>The material underlying the shoreline and shoreface converted to mobile sediment as it is exposed by shoreline erosion. The lithology is parameterized by two quantities that can vary across the model domain: the maximum weathering rate (which occurs when the shoreface is bare of sediment) and the composition of the resulting sediment (percentage coarse enough to stay in the nearshore system. See Valvo et al. (2006) for a full explanation of how underlying geology is treated.</br></br>Where beach nourishment is deemed by the user to be occurring, if the gradients in sediment flux would cause the shoreline to erode landward of a pre-determined location, sediment is added at the rate required to prevent such shoreline change. Hard structures are treated as if the lithology has a maximum weathering rate of 0.hology has a maximum weathering rate of 0. +
Years to millenia. Typically, the model is … 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.)re implicitly averaged out in this model.) +
Active +
2,011 +
The Coastline Evolution Model (CEM) addres … 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.ough beach nourishment or hard structures. +
A. Brad +
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Binary +
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0.36 +
20 Mb +
Coastal +
coastline +, model +, spatial scales ranging +, addresses predominately sandy +, time-scales ranging +, ranging from years +, scales ranging +, addresses predominately +, years to millenia +, spatial scales +, coastline evolution model +, coastline evolution +, ranging from kilometers +, hundreds of kilometers +, kilometers to hundreds +, wave-dominated coastlines +, ranging +, coastal evolution + and cem +
As code +
coastal evolution +
Single +
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16:36:06, 6 June 2025 +
13 +
Coastline evolution model +
Box 90230 +
27708-0230 +
false +
BSD or MIT X11 +
days +
Through CSDMS repository +
https://github.com/csdms-contrib/cem +
Landscape-Scale +
2000 +
Project manager +
Matlab +
Note: if using the JPEGs automatically generated, the answer to the visualization question is 'no.' +
