Development and Prediction of Bed Armoring

The major purposes of this study are to use available data to predict: (1) The development of bed armoring; and (2) the final composition of grain size distribution. First, the different factors influencing the incipient motion for nonuniform sediment size distribution are examined. Then, the procedures for simulating the grain size distribution of the armor layer are developed based on modifications of Gessler's procedure and Einstein's hiding factor. Three regression equations are derived to predict the median size, d30 and d84, of the final armor bed, given the initial sediment bed size distribution and flow conditions. A modified Shields diagram for incipient motion for nonuniform sediment sizes is also suggested.