Unravelling flood history using matrices in fluvial gravel deposits

Experiments carried out in a laboratory flume have shown that the infiltration of sands into gravels is largely controlled by flood magnitude and frequency. Three sets of experiments were used to simulate low flows, small floods and large floods and these showed that at low and moderate flows almost all sand stays close to the surface; however, during large flood events the surface framework particles are entrained, the bed dilates and material falls through the pore spaces and accumulates at the base of the bed. In addition, bed load transport is enhanced when gravels are mixed with sand and heavy and light minerals become separated. These results suggest that the distribution of matrices in gravels carries with it a signal linked to flood history which might be unravelled given careful research.