Model help:AgDegNormalGravMixHyd
AgDegNormalGravMixHyd
This is a module that calculates the evolution of a gravel bed river under an imposed cycled hydrograph.
Model introduction
The module calculates the evolution of a gravel bed river under an imposed cycled hydrograph.
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
A list of the key equations. HTML format is supported; latex format will be supported in the future
Notes
This program computes the time evolution of the long profile of a river of constant width carrying a mixture of gravel sizes, the downstream end of which has a prescribed elevation. In particular, the program computes the time evolution of the spatial profiles of bed elevation, total gravel bedload transport rate and grain size distribution of the surface (active) layer of the bed.
The flow is specified in terms of a hydrograph repeated a specified number of times annually, rather than a constant flood discharge and an intermittency.
The river has constant width. The upstream point, at which sediment is fed, is fixed in the horizontal to be at x = 0. The vertical elevation of the upstream point may change freely as the bed aggrades or degrades.In the program it is assumed that all gravel reaching the topset-foreset break is captured in the delta.
The reach has constant length L, so that the downstream point is fixed in the horizontal at x = L. This downstream point has a user-specified initial elevation ηdI.
Gravel bedload transport of mixtures is computed using the Parker (1990) surface-based formulation. Sand and finer material must be excluded from the grain size distributions before implementing this relation.
The grain size distributions of the sediment feed, initial surface material and substrate material must be specified. It is assumed that the grain size distribution of the sediment feed rate does not change in time, the initial grain size distribution of the surface material is the same at every node, the grain size distribution of the substrate is the same at every node and does not vary in the vertical. These constraints are easy to relax.
The program does not store the vertical and streamwise structure of the new substrate created as the bed aggrades. As a result, is cannot capture the case of aggradation followed by degradation. Again, the constraint is easy to relax, but at the price of increased memory requirements for storing the newly-created substrate.
In performing the calculation, the following control parameters must be specified: M = number of spatial intervals, so that the spatial step length = L/M. dt = time step length; Mtoprint = number of time steps to a printout; Mprint = number of printouts in the calculation.
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: http://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
Key papers
