Interaction between Flow and Seepage in an Alluvial Channel

Abstract

The hydrodynamics of an alluvial channel was explored in a sloping flume by taking into account the significant impact of upward seepage. In a sand bed channel, Seepage occurs as lateral flow which is an important explicit parameter. To understand the sediment transport and to keep an active river ecosystem in a channel, the configuration of the main flow and seepage flow in a channel is essential. Therefore, to determine the impact of upward seepage on the hydrodynamic of an alluvial channel, experiments were carried out for both the no seepage and upward seepage runs. The 3-D instantaneous flow velocity was measured at a certain depth using Acoustic Doppler velocimeter (ADV) which give crucial outcomes related to the turbulence in flow. Various features of turbulent flow i.e., time-averaged velocity, turbulence intensity and Reynolds shear stresses, were analyzed for the case of no seepage and seepage flow. As per the results the degree of turbulence reduced with upward seepage, indicating less sediment movement. With an upward seepage, the turbulent length scale also diminishes, leading to reduction in energy and momentum transfer due to the size of the larger eddy at the region near to the bed surface, eventually leading to sediment flow due to upward seepage. Civil or hydraulics engineers will get benefit from the findings of this study as per the knowledge of the characteristics of seepage flow which will improve sediment management in natural rivers.