Author(s): Xiaotian Chen; Kairong Wang; Qiwei Zhang; Yong Li
Keywords: Sediment carrying capacity; One-valued; Dual-valued; Accretion; Erosion; Deposition
Abstract: As a dependent function, sediment-carrying capacity has two corresponding values for one representative independent parameter. Its dual-valued feature reflects mutual-controlling relationship between flow and the suspended and bed materials, and the law governing the inter-exchange between flow and alluvial channel as well. It is indicated that the riverbed under siltation will be covered with finer and finer particles while the riverbed under erosion will be covered with coarser and coarser particles, i. e., armoring, so the dual-valued relationship could be more reasonable than the one-valued ones. With the data measured on the physical models and in the field, the authors modified the velocity formula established by Sha (1985) by introducing a parameter of sediment concentration. Furthemore, they established formulas for critical accretion and erosion by introducing the concept of effective velocity. These formulas can cope with sedimentation problems regardless of whether the flow is low-or hyper-concentrated. Especially, the formulas can describe better the feature of the Lower Yellow river under erosion for a relatively clear oncoming flow. The formulas are validated through the comparison of the field data measured on the lower Yellow River with the present theory.