Does the stream power theory have a physical foundation?

The minimum entropy production principle (mEPP) for flow in a wide rectangular channel shows that the entropy production rate is equal to the unit stream power divided by the product of temperature and flow depth. Only for isothermal, steady, uniform flow is an extremum of the entropy production equivalent to an extremum of unit stream power. For a sediment-carrying channel, minimization of unit stream power provides a linear relation between …