Sediment transport in hyperconcentrated flows in sand-bed streams of volcanic origin

Abstract : This study advances the understanding of sediment transport of bed material discharged in sand bed channels through application of recently developed theoretical concepts related to the effects of high concentration of suspended sediment on rheological properties of the water-sediment mixture. It demonstrates the utility of developing empirical adjustment coefficients for fine material concentration (d sub 50 < 0.0625 mm) that can be used in the Colby method for predicting total bed material discharge from gaging and sediment sampling data commonly available to the engineer. The prototype data set used was collected and reported by the US at four gaging and sediment sampling stations along a 27-mile reach of the Cowlitz and Toutle rivers, Washington, 1 Oct 81 - 30 Sep 82. The data set included stream gaging measurements, bed material samples, and depth-integrated suspended sediment measurements. The modified Einstein method was used to estimate the total bed material discharge, and the fluid properties were varied according to recently developed methodologies that take into account the increase in viscosity and density due to suspended sediment concentration.