Entrained and Bed‐Load Sand Concentrations in Waves

Abstract

Using various types of basic empirical results, equations are developed for average volumetric concentration of sediment moving as bed load in nearshore wave environments. Laboratory and natural situations have appreciably different dependences of bed‐load concentration on peak flow velocity, with laboratory sediment concentrations being commonly larger than those in nature. Critical examination of published concentration measurements isolates several subsets of near‐bed data for quartz sands which allow the two expressions for bed‐load concentration to be evaluated. Field and laboratory results in separate categories exhibit distinct functional trends and some quantitative magnitudes agreeing with calculated bed‐load concentrations, so that calculation might give a reference value useful for suspended‐load computation. Evidence permits a firm conclusion that laboratory near‐bed processes and suspended sediment concentrations in usual conditions do not pertain to important field situations.