Bedload and channel morphology along a braided, sand-bed channel: insights from a large flume

This paper presents insights from a flume experiment investigating the relationship between rate of bedload transport exiting a reach of a braided, sand-bed channel and the channel's braid intensity. The self-forming nature of the anabranches (sub-channels forming the braided channel) meant there was little direct control over the morphology of the braided channel. A comprehensive dataset was obtained relating rate of bedload transport and a braiding parameter, W/B, used to characterize braid intensity; W = width of actual water flow, and B = flume width. As W/B increased, the rate of bed-sediment transport decreased. However, spatial and temporal variations in sediment transport rate and channel morphology complicate this relationship. The clarity of the relationship improved when values of W/B were determined closer to the location where sediment transport was measured. Local morphologic features, such as sheet flow and antidunes, are shown to influence braid formation and thereby affect bedload transport.