Model help:BackwaterWrightParker

BackwaterWrightParker

This is used to calculate backwater curves in sand-bed streams, including the effects of both skin friction and form drag due to skin friction.

Model introduction

This program calculates backwater curves over a sand-bed stream with a specified spatially constant bed slope S. The calculation uses the hydraulic resistance formulation of Wright and Parker (2004) (without the flow stratification correction), as well as calculating the normal depth.

Model parameters

Input files and directories

Run Parameters

About

Parameter	Description	Unit
Input directory	Path to input file
Site prefix	site prefix for Input/Output files	-
Case prefix	Case prefix for Input/Output files	-

Parameter	Description	Unit
bed slope		-
Submerged specific gravity of sediment		-
Median grain size (D50)		-
Grain size such that 90% passes (D90)	grain diameter such that 90% of the distribution is finer	mm
channel width (B)		m
flow discharge (Q)		m3 / s
downstream water surface elevation (k)		m
reach length (L)		m
number of spatial nodes (max of 99)		-

Parameter	Description	Unit
Model name	name of the model	-
Author name	Name of the model author	-
Median grain size (D50)		-

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

Nomenclature

Symbol	Description	Unit
R	sediment specific gravity, R+1	-
B	channel width	m
D	grain diameter such that 90% of the distribution is finer	mm
S	bed slope	-
d	median grain diameter	mm
Q	flow discharge	m3 / s
k	downstream water elevation	m
L	reach length	m
M	number of spatial intervals
τs,min	minimum shear stress due to skin friction
ηd	downstream water surface elevation	m
Frd	Froude number	m

Output

Symbol	Description	Unit
x	downstream coordinate	m
η	bed surface elevation	m
ksi	water surface elevation	m
H	flow depth	m
Hs	flow depth due to skin friction	m

Notes

• Note on input parameters:

If the minimum shear stress due to skin friction τ_s,min, calculation bombs at any point the program will end.

If the height due to skin friction Hs, calculation bombs, the program will assign the last value in the calculations to Hs.

If the H_norm calculation bombs, the value for H_norm is not outputted, but this does not affect the other values that are calculated.

This program requires a given downstream water water elevation, η_d, such that Fr_d < 1, because the flow is assumed subcritical, and the program will alert the user and quit if the condition is not met.

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)

Gary Parker

References

• Wright, S. and G. Parker, 2004, Flow resistance and suspended load in sand-bed rivers: simplified stratification model, Journal of Hydraulic Engineering, 130(8), 796-805.

Links

Any link, eg. to the model questionnaire, etc.