The Channel That Carried 5.69 Cubic Meters per Second
Hydraulic radius is not automatically equal to flow depth. Manning discharge depends on area, wetted perimeter, roughness, and slope.
Topic: Fluid Mechanics Hydraulics
The Faster Pipe Section That Lost 16 kPa of Pressure
A horizontal pipe can still lose static pressure when the flow accelerates because velocity head increases.
The Pipe That Halved Its Diameter and Quadrupled Its Velocity
Halving pipe diameter reduces area to one-quarter, so constant-flow velocity becomes four times larger.
The Tank Gauge That Read 58.9 kPa at 6 m
Zero velocity does not mean zero pressure. A static water column develops pressure that increases with depth.