Bed Resistance and Sediment Transport Experiments inSand, Gravel and Sand-Gravel Antidunes

摘要

Experiments in a 30m-long tilting flume, with sediment feeding rates as high as 1 kgper second, were performed with sand, gravel and two mixtures of these materials.Mobile-bed equilibrium was sought under near-critical flow regimes to resemble thehigh sediment transport capacity of torrential ephemeral streams on theMediterranean area. The flume was equipped with a system to separately measuresand and gravel discharges, so that it was possible to accurately determine themobility of each size-fraction. The main bed features observed were 3D and 2Ddownstream migrating antidunes, in coexistence with alternate bars. We presentpreliminary results for the experimental observations. Bed resistance and grain-related bed shear stress were computed. A comparison is presented with the Meyer-Peter and Muller sediment transport formula, which showed an underestimation trendfor the experimental conditions.