Menu of Coupled Velocity and Sediment‐Discharge Relations for Rivers

Abstract

Nonlinear multiple‐regression analysis is used to derive relations among the velocity, sediment discharge, bed‐form geometry, and friction factor of alluvial rivers. A data base comprising 339 river flows and 608 flume flows is used in the analysis. A hierarchy of formulations involving progressively more interdependencies among velocity, depth, sediment discharge, and bed‐form geometry is developed. Procedures for computing velocity‐ and sediment‐rating curves are presented. A simplified procedure for preparing depth‐discharge relations for streams with strongly, discontinuous rating curves is also presented. Rating curves for four rivers, and computed depths and velocities for two others, are presented. The accuracies of the different methods are evaluated in terms of the mean normalized errors of predicted friction factors, depths, velocities, and sediment discharges. It is concluded that these formulations yield velocity‐ and sediment‐rating curves that are as reliable as is permitted by the accuracy of the available data, which is limited by, among other things, the inherent short‐term temporal variability of stream‐flow properties.