# Open-channel flow estimate
# Scope: Manning uniform flow in a supplied rectangular channel; SI n carries time/length power.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

width = 1 m
depth = 0.3 m
slope = 0.001
roughness = 0.015 "Manning n numerical value in SI convention"

area := width*depth [m^2]
radius := area/(width+2*depth) [m]
flow := area*(radius/(1 m))^(2/3)*sqrt(slope)/roughness*(1 m/s) [m^3/s]

check flow capacity target: flow >= 0.15 m^3/s

scenario alternative: width = 0.8 m