This equation will affect only the timing of the return flow and not the total volume. Its volume is estimated from the equations where ETact is the actual evapotranspiration occurring in the soil profile, r is the revap coefficient, and revapst is the revap storage. Routing Component Reach routing operates on a daily time step and requires no iteration. Also, the need for detailed channel cross-section data has been eliminated. Flow rate and average velocity are calculated using Manning's equation.
Travel time is computed by dividing channel length by velocity.
These calculations are computed for full channel depth and a depth of 0.1 times the full depth. The procedure is repeated for a depth of 1.5 times the full depth. Outflow is then adjusted for transmission losses, evaporation, diversions, and return flow. Storage in the reach is calculated from the balance equation. Transmission Losses .