Theory 74/River & Floodplain/Channel form
Channel Form Is Strength Against Flow
The claim
River channel form is set by the ratio of bank strength to flow energy, so a cohesive-bank river is narrow and deep where a sandy one is wide and shallow.
01Mechanism
Width adjusts until bank shear equals strength; the ratio determines the equilibrium geometry.
02Prediction
Width-depth ratio should track the ratio.
03Refutation
Geometry tracking discharge alone would remove bank strength.