Model help:RiverWFRisingBaseLevelNormal
RiverWFRisingBaseLevelNormal
This model is a calculator for disequilibrium aggradation of a sand-bed river in response to rising base level.
Model introduction
This program uses a Chézy formulation and either the Engelund-Hansen relation for bedload in sandy streams or the Parker relation for bedload in gravel bed streams assuming a uniform grain size to solve for the bed evolution, width evolution, and depth evolution in time and space.
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
| Symbol | Description | Unit |
|---|---|---|
| Qbf | flood discharge | m3 / s |
| Qtbf,feed | upstream bed material sediment feed rate during flood | m3 / s |
| Λ | units of wash load deposited in the fan per unit bed material load deposited | |
| If | intermittency | - |
| D | grain size of bed material | mm |
| R | submerged specific gravity of sediment (e.g. 1.65 for quartz) | - |
| L | reach length (downchannel distance) | m |
| Bf | floodplain width | m |
| Ω | channel sinuosity | - |
| λp | bed porosity | - |
| Cz | Chezy resistance coefficient | - |
| Sfbl | initial fluvial bed slope | - |
| dηd / dt | rate of rise of downstream base level (should be positive) | mm / year |
| M | number of intervals | - |
| Δx | spatial step | m |
| Δt | time step | year |
| Mtoprint | number of time steps to printout | - |
| Mprint | number of printouts | - |
| e | rate of downstream base level rise | mm / yr |
| p | number of prints | - |
| i | number of iterations per print | - |
| t | time step | yr |
| y | year the base level change begins | yr |
| Y | year the base level change ends | yr |
| a | coefficient in the Engelund-Hansen 1967 load relation | yr |
| n | exponent in the Engelund-Hansen 1967 load relation | - |
| T | channel-forming Shields number for sand-bed streams | - |
| P | coefficient in the Parker 1979 load relation | - |
| N | exponent in the Parker 1979 load relation | - |
| c | critical Shield number | - |
| G | channel-forming Shields number for gravel-bed streams | - |
| x | downstream coordinate | m |
| Hbf | bankfull water depth | m |
| Bbf | bankfull channel width | m |
| η | bed surface elevation | m |
| Sl | bed surface slope | - |
| qbT | volume bedload transport per unit width | m2 / s |
Output
| Symbol | Description | Unit |
|---|---|---|
| Cf | friction coefficient | - |
| τform * | channel-forming Shields number | - |
| Hn | normal depth at given Qbf and Qtbf,feed | m |
| Sn | normal slope at given Qbf and Qtbf,feed | - |
| Bn | normal width at given Q<bf> and Qtbf,feed | - |
| Frn | normal Froude number at given Qbf and Qtbf,feed | - |
Notes
This program is a companion to the program SteadyStateAg, which computes the steady-state aggradation of a river with a specified base level rise at the downstream end. This program computes the time evolution toward steady-state aggradation.
The calculation assumes a specified, constant Chezy resistance coefficient Cz and floodplain width Bf. The sediment is assumed to be uniform with size D. All sediment transport is assumed to occur in a specified fraction of time during which the river is in flood, specified by an intermittency. If grain size D < 2 mm the Engelund-Hansen (1967) formulation for total bed material transport of sand is used. If grain size D >= 2 mm the Parker (1979) bedload transport formulation for gravel is used. The flow is computed using the normal flow approximation. The reach has downchannel length L, and base level is allowed to rise at a specified rate at the downstream end.
- Note on model running
For the characteristic grain size, a value of < 2 mm will use the Engelund-Hansen relation, whereas ≥ 2 mm will use the Parker relation.
The output yields the bed elevation, width, and depth, the user simply needs to scroll down to find the width and depth values.
Due to the evolution that is occurring in time, the GetData function has been included in this function, and works the same way as in the AgDeg programs
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
