Flume Experiments to Explore Bedload Transport in Sand and Gravel Mixtures

A series of bedload transport experiments were conducted in a laboratory flume at the University of Hull, UK to explore the effects of sand and gravel mixtures on bedload transport rates. The experiments were designed to observe bedload transport under uniform flow conditions with two different sediment size distributions. A narrow distribution of gravel only and a sediment mixture containing sand and gravel were used and data collected included PIV data, images of the bedload transport and periodic laser scans of bed elevation. The laboratory flume at the University of Hull is 30 cm wide and 6 meters long and the bed slope was set at 1%. Initial analysis of the results indicate an initial period of enhanced transport when sand is added to the gravel mixture, however over a longer period transport rates over the entire period of the experiment did not differ significantly. This poster will present the differences in transport rates observed between the two sediment size distributions. Additionally, preliminary analysis of the bed elevation data will be presented to explore mathematical methods for using the scan data to characterize changes in bed topography and roughness over the time of experiments.