Model help:Avulsion
Avulsion
This model illustrates the realistic looking deltas generated by a stochastic process.
Model introduction
The model assumes that an avulsion happens every time step, the basin is flat-bottomed, and the grid scale is such that one cell is always filled by the river’s sediment with every time step. The model randomly generates angles from the distribution X, moves the mouth of the distributary by these angles around the coastline, and fills empty cells with sediment. A uniform distribution builds a symmetric and radial delta while the normal distribution creates a more lobe-like delta. These river-dominated delta morphologies would change with the inclusion of waves, tides, and other processes.
Model parameters
Uses ports
This will be something that the CSDMS facility will add
Provides ports
This will be something that the CSDMS facility will add
Main equations
- Angular position of the distributary channel after n+1 avulsions
[math]\displaystyle{ \Theta _{n+1} = \Theta _{n} + X_{n} }[/math] (1)
| Symbol | Description | Unit |
|---|---|---|
| X | distribution used in the equation | - |
| Xn | nth realization of X (changes of angle for X distributary after the nth time step) | - |
| Θn | current angle of X distributary before the nth time step | - |
| Θn+1 | current angle of X distributary after the nth time step | - |
Notes
In this model, the angular position of the distributary on the delta is the sum of angular jumps (Xn) that are generated from the distribution X. Regardless of the underlying physics, some probability distribution must represent this change in angle. The precise distribution will not be known, but observations of large deltas suggest that the probability of avulsing somewhere nearby is high, while the probability of larger avulsions is low (Milliman et al., 1987).
Examples
An example run with input parameters, BLD files, 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
- Milliman, J.D., Qin, Y.S., Ren-Meie, E., Saito, Y., 1987. Man’s influence on the erosion and transport of sediment by Asian rivers; the Yellow River (Huange) example. Journal of Geology 95 (6), 751–762.
- Hutton E. W. H., Syvitski, J. P. M., 2008. Sedflux 2.0: An advanced process-response model that generates three-dimensional stratigraphy. Computers&Geosciences, 34: 1319~1337, Doi: 10.1016/j.cageo.2008.02.013.
