Sediment supply and relative size distribution effects on fine sediment infiltration into immobile gravels

We present results and analyses from flume experiments investigating the infiltration of sand into immobile clean gravel deposits. Three runs were conducted, each successive run with the same total sediment feed volume, but a 10‐fold increase in sand feed rate. The highest sand feed rate produced less sand infiltration into the subsurface deposits than the other two runs, which had approximately equivalent amounts of sand infiltration. Experimental data, combined with simple geometric relations and physical principles, are used to derive two relations describing the saturated fine sediment fraction in a gravel deposit and the vertical fine sediment fraction profile resulting from fine sediment infiltration. The vertical fine sediment fraction profile relation suggests that significant sand infiltration occurs only to a depth equivalent to a few median grain diameters of the bed material.