Open channel Flow Calculation

[rfb3]

Good afternoon, it has been a while since I calculated the flow in an open channel pipe.
I have a 36 inch concrete pipe with 4 inches of flow.
The slope is 1 ft./100 ft.
I currently do not know the velocity of the flow.
Can anyone direct me to an Excel spreadsheet to the best way to determine the flow in this pipe?
Thank you

 

[1503-44]

Manning equation

https://duckduckgo.com/?q=manning+equation&t=brave&ia=about

A black swan to a turkey is a white swan to the butcher.

 

[gbam]

FHWA Hydraulic Toolbox

https://www.fhwa.dot.gov/engineering/hydraulics/software/toolbox404.cfm

 

[bimr]

Free Mannings Calculator #1

Free Mannings Calculator #2

 

[rfb3]

Thank you so much!
Great links