Open Channel Flow (mannings equation)

[Stacyg]

A trapezoidal channel with side batters 1:1 and Manning's n value of 0.025 has a bed slope of 0.0045 m/m. When the depth is equal to the bottom width the discharge is 7.5 m^3/s. Calculate the bottom width to the nearest 0.01m.

Using mannings equation

V= 1/n.R^2/3.S^1/2

S=0.0045 n=0.025 Q=7.5

Q=V.A V=Q/A

I don't know where to start I know how to use the equation and we have been shown how to use some graphs for the solution of mannings formula but I'm not sure on using them.
Any help would be great thanks

 

[civilGuy20]

Hey,

I guess you may have found the answers you are looking for. But just in case you are still searching go to http://flowsizer.com" they have a nice clean mannings calculator that will get you the answers to those equations