Effects of suspended sediment on river bars

Meles Siele Tewolde

Tuesday 30 june 2015

18:00 - 18:03h

Parallel session: Poster pitches: 7A. Sediment - Erosion

Bars are large sediment deposits in river channels emerging at low flows with wavelength and height scales of the order of channel width and flow depth, respectively. They consist of recurring sequences of erosion holes and deposition fronts and develop due to morphodynamic instability of flat river beds. Bars create problems to river navigation, intakes, and cause bank erosion, making their morphological study and management an important part of river engineering and rehabilitation works. As rivers normally have both fine and coarse sand, studying the development and characteristics of bars should include both bed and suspended sediment processes. However, most theories for bar instability are based on bed load transport, assuming an immediate adaptation of sediment transport to the local flow conditions. Only a few theoretical works focus on the effects of suspended sediment transport on bars. Moreover, experiments showing the effects of suspended sediments are still lacking. This research is conducted to fill this gap. It investigates the effects of both bed load and suspended load transport on bar characteristics based on laboratory investigations and 3D numerical simulations upscaling the flume experiments.