ERRORS OF KINEMATIC-WAVE AND DIFFUSION-WAVE APPROXIMATIONS FOR TIME-INDEPENDENT FLOWS IN INFILTRATING CHANNELS

Time-independent (or steady-state) cases of channel flow were treated and errors of the kinematic-wave and diffusion-wave approximations der ived for finite flow at the upstream end. The diffusion-wave approxima tion was found to be in excellent agreement with the dynamic wave repr esentation, with error magnitudes of 0.2% for values of KF0(2) greater -than-or-equal-to 7.5, where K is the kinematic-wave number and F0 is the Froude number. Even for small values of KF0(2) (e.g., KF0(2) = 0.7 5), the errors were typically in the range of 1.3 to 3.7%. The approxi mate analytical diffusion-wave solution performed poorly with error ma gnitudes greater than 30% even for large values of KF0(2). The kinemat ic-wave approximation was also found to be in good agreement with the dynamic-wave representation with errors of about 1.2% for KF0(2) = 7.5 and varying from 15 to 44% for KF0(2) = 0.75.