Downstream Velocity Increases: (Bradshaw Model)
Discharge and load quantity ↑
HR ↑ as channel width&depth ↑
Slope Gradient ↓ (thus, slope effect < HR)
Roughness: ↓ particle size, ↓ roughness ↓ friction, ↑ efficiency ↑ velocity
(Friction = channel bed + banks + vegetation + sediment load + friction from water)
Generally, downstream:
↑ discharge, HR ↑ , ↓ water in contact with wetted perimeter, ↓ friction, ↑ velocities, ↑ efficiency