Transient Flow in an Open Channel Bound by Two Step Pumping Stations

Abstract

Pumping stations play a great role in open channel flow applications. After starting pump units in the pumping stations, unsteady flows in the open channel are immediately generated. In this paper, the behavior of unsteady flow in a prismatic trapezoidal channel between two step pumping stations is studied. A mathematical model is constructed to simulate one-dimensional, unsteady, gradually-varied open channel flow in the channel. The soil leakage and evaporation from the water surface along the channel are also involved. The Lax diffusive scheme is applied to solve the proposed model. The model is applied on a real open channel located in China. The accuracy of the model is calculated by varying the scheme grid steps. We also calculate and discuss the water surface elevation, the flow rate and the lateral outflow per unit length, as well as several influential factors at various stages along the channel. In this work, the wave propagation mechanism is clearly presented and analyzed. The computed results show that the water surface profile in the open channel varies continuously over time until it becomes almost constant. Thus, the pumping station operation duties change over time. The accuracy of the results is validated by comparing the computed results with measured data.