Experimental study on near-bed flow turbulence of sinuous channel with downward seepage

The presence of a small seepage velocity in streams and rivers induces transfer of mass and momentum near the sediment boundary, causing bank failure and instability of hydraulic structures. This experimental study is intended to report near-bed hydrodynamics and morphological characteristics under the impact of downward seepage. A laboratory investigation was conducted in a sinuous rectangular alluvial channel with rigid sides and movable uniform sand bed. From the distribution of Reynolds shear stress (RSS), the transverse or radial motion of the sediment across the bend was identified. High values of RSS in the outer region relate to higher momentum flux, eroding the outer bend. The contribution probability of ejection and sweep events are highest in the bend region. For seepage, the contribution probability of the events has increased. Moreover, the altered flow with seepage affected the transport of sediment and caused noticeable modifications along the channel bed. With seepage, the erosion rate has been enhanced along the outer bend of the channel.

Automated summary

The experimental study reveals that under seepage, there are significant changes in the near-bed hydrodynamics and morphological characteristics, with increased momentum flux in the outer region leading to intensified erosion in the outer bend.