Effect of Floodplain Non-submerged Vegetation on Bed Variation in Meandering Compound Rivers

Scouring and variations of bed topography in meandering river is one of the most interesting issues in river engineering. Vegetation is a significant feature of rivers. Various studies have shown that the presence of vegetation may have an important impact on flow field and river morphology. Due to the complex geometry and hydraulics of flow in natural rivers, physical or mathematical models are often useful to evaluate morphological variations. The purpose of the present study is to investigate the morphological changes in alluvial meandering rivers with compound cross section to gain insight into the physical processes involved. Hence, the bed topography in an alluvial meandering asymmetric compound channel is assessed with vegetated and non-vegetated floodplain conditions. Cylindrical rods of 10 mm diameter were used to simulate rigid vegetation. The rods were installed over the floodplain in two parallel patterns with one row and two rows of vegetation, respectively. The results showed that the point of maximum scour depth was located near the outer bank. Due to high flow velocity entering the bend, the scour depth at section entrance of the bend was greater than other sections. Also, the thalwege was moved away from the interface after planting the vegetation.