The effect of floodplain roughness on flow structures, bedforms and sediment transport rates in meandering channels with overbank flows: Part II

A series of experiments were conducted to understand the behaviour of flow resistance and sediment transport rate within compound meandering channel whilst changing floodplain roughness. The detailed flow structures with bedforms were reported in Part I of this paper. This second sister paper concentrates on the behaviour of bedforms, sediment transport rate and flow resistance during flood conditions. The bedforms along the meandering channel with various overbank flows are presented and interesting bed features observed. The changing sediment transport rates with various water depths are also shown and the sediment transport rate first decreases and then increases during flood. The initiation of this increase appears closely related to the ratio of the floodplain velocity to the main channel velocity in this configuration. The Manning n values in the meandering are established using both the sediment transport data and the velocity data from Part I. Both the n values are highly correlated. For the floodplain, the flow resistance obtained from the velocity data also highly correlates with that obtained from 2D flow experiment.