Effect of Increasing Antecedent Flows on Equilibrium Bed-Load Transport Rates in a Laboratory Channel with a Sand and Gravel Bed Channel

Abstract

Experiments were conducted in a laboratory flume in which gravel and total bed-load rates were measured continuously using independent methods that allowed evaluation of the effect of four antecedent flow conditions on the transport of bed load under standard flow. It was found that both mean total bed-load rate and gravel transport rates are related to the magnitude of antecedent flow. The changes in mean bed-load rates were attributed to changes in the stability of the coarsest fractions of the bed material, caused by the previous high-flow event. This work indicates that long-term mean bed-load transport rates for a sand and gravel bed are not just a function of grain size and flow rate but also vary with the magnitude of antecedent flow.