Model help:DeltaBW: Difference between revisions
No edit summary |
mNo edit summary |
||
Line 513: | Line 513: | ||
==Links== | ==Links== | ||
* [[ | * [[Model:DeltaBW]] | ||
[[Category:Utility components]] | [[Category:Utility components]] |
Revision as of 15:16, 24 May 2011
DeltaBW
This is used to Calculate evolution of long profile of a river ending in a 1D migrating delta, using a backwater formulation.
Model introduction
This program calculates bed surface evolution for a narrowly channelized1D fan-delta prograding into standing water using a backwater formulation, as well as calculating the final water surface of the system and the mass balance of sediment in the system.
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
- Critical water depth
[math]\displaystyle{ H_{crit} = \left ( q_{w} ^ 2 / g \right ) ^ \left ( {\frac{1}{3}} \right ) }[/math] (1)
Symbol | Description | Unit |
---|---|---|
qw | water discharge / width | m2 / s |
If | intermittency | - |
Cz | dimensionless Chezy resistance coefficient | - |
D | grain size of sediment | mm |
R | submerged specific gravity of sediment | - |
λp | bed porosity | - |
qtf | sediment input rate | - |
at | coeff in total bed material load relation | - |
nt | exponent in load relation | - |
τsc * | critical Shields stress in load relation | |
εd | water surface elevation of the lake | m |
ηsl | initial elevation of top of the foreset | m |
ηbl | initial elevation of bottom of the foreset | m |
Sfl | initial fluvial bed slope | - |
Sb | subaqueous basement slope | - |
sfl | initial length of fluvial zone | m |
sfmax | maximum length of fluvial zone | m |
Sa | slope of foreset face | - |
Δt | time step | days |
M | number of fluvial nodes | - |
Mtoprint | number of steps until a printout is made | - |
Mprint | number of printouts after the initial one | - |
Hi | initial depth at top of foreset deposit | m |
Hcrit | depth for Froude-critical flow | m |
Ui | initial flow velocity at top of foreset deposit | m / s |
τsi | initial Shields stress at top of foreset | m / s |
Hni | normal depth associated with initial slope | m |
Cf | friction coefficient | - |
dt | time step | s |
dxbar | dimensionless spatial step | s |
τsn | normal Shields stress associated with qw and qtf | |
Sn | normal slope associated with qw and qtf | |
Hn | normal depth associated with qw and qtf | m |
Frn | normal Froude number associated with qw and qtf | |
x | downstream coordinate | m |
η | bed surface elevation | m |
Sl | bed slope | - |
qb | volume bedload transport per unit width | m2 / s |
H | water depth | m |
τ | shear stress | N / m2 |
sbb | reach of the alluvium bottom | m |
sss | reach of the alluvium top | m |
etaup | upstream bed surface elevation | m |
etatop | bed surface elevation of the top of the forest | m |
etabot | bed surface elevation of the bottom of the forest | m |
q | flood discharge | m2 / s |
I | flood intermittency | - |
Q | upstream bed material sediment feed rate during floods | m2 / s |
D | grain diameter | mm |
Cz | coefficient in the Chezy rlation, Cf | - |
n | exponent in the load relation | - |
T | critical shields stress in load relation | - |
E | elevation of the top of the forest | m |
e | initial elevation of the bottom of the forest | m |
f | initial fluvial bedslope | - |
b | subaqueous basement slope | - |
s | initial length of the fluvial zone | m |
m | maximum length of the fluvial zone | m |
S | slope of the forest face, Sa | - |
R | submerged specific gravity | - |
L | bed porosity | - |
k | coefficient in the Manning-Strickler relation | - |
a | coefficient in the total bed material load relation | - |
r | coefficient in the Manning-Strickler relation | - |
M | number of fluvial nodes | - |
t | time step | days |
p | number of prints | - |
i | number of iterations per print | - |
Output
Symbol | Description | Unit |
---|---|---|
qbT | total volume gravel bedload transport rate per unit width summed over all sizes | - |
v | flow velocity | m / s |
τsg | shield stress | kg / (m s) |
Notes
This module is a calculator for 1D Subaerial Fluvial Fan-Delta with Channel of Constant Width. This model assumes a narrowly channelized 1D fan-delta prograding into standing water. The model uses a single grain size D, a generic total bed material load relation and a constant bed resistance coefficient. The channel is assumed to have a constant width. Water and sediment discharge are specified per unit width.The channel is assumed to have a constant width. Water and sediment discharge are specified per unit width. The fan builds outward by forming a prograding delta front with an assigned foreset slope. The code employs a full backwater calculation.
- Note on model running
A uniform grain size is assumed, and the same choice of Manning Strickler or Chézy is posed to the user.
The fan builds outward by forming a prograding delta front with an assigned foreset slope.
If the flow becomes supercritical, the backwater calculation will fail, so the program automatically alerts the user and exits.
The initial depth at the top of the foreset must be greater than the critical water depth Hcrit; if it isn't the program will alert the user and exit
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