The influence of vegetated alternate bar on flow resistance in an alluvial straight channel

Abstract

Alternate bars significantly affect river characteristics, especially bed roughness and flow resistance. Additionally, the presence of vegetation on the bar surface impacts river hydrodynamics and morphology significantly. However, the details on their impacts are insufficient for us to interpret. This study analyzes the interaction of vegetation and alternate bars with the flow resistance in an alluvial river. The study aims to investigate the bed roughness parameters of Darcy’s friction factor and Manning’s roughness coefficient that impacted from vegetated alternate bars. The study was based on experimental analysis. A straight flume channel 10 m long and 1 m wide was used with bed material of uniform sediment size 0.8 mm. The measurement was made based on the seven cross-sections created along the channel. The obtained results revealed that the friction factor and Manning’s roughness coefficient were significantly increased on the vegetated alternate bar compared with the other areas in the channel. Thus, the resistance of flow increased around the vegetated alternate bar as the bed roughness increased.