Dilution Discharge Measurement During Flood Wave

Abstract

A severe restriction to dilution discharge measurements is that they are to be applied to steady-flow conditions only. Using a computational model, dilution discharge measurements by constant-rate injection are simulated during unsteady-flow conditions caused by a Gaussian flood wave propagating down a prismatic channel with rectangular cross section. The accuracy of the discharge measurement is deduced from the computational results. The main source causing discrepancies between the actual and measured discharges is the difference in propagation velocities of the tracer cloud and the flood wave. Correction procedures are recommended, since maximum inaccuracies can easily be larger by an order of magnitude than inaccuracies during steady flow conditions.