A New Formula for the Transport Capacity of Nonuniform Suspended Sediment in Estuaries

A new formula for calculating the sediment transport capacity is developed as a function of the time-dependent Froude number and the particle Reynolds number. Considering the relation between suspension and transport of sediment, a critical condition for suspension is introduced into the formula. The proposed formula provides a consistent formulation for the fractional and total transport capacity of nonuniform sediments and leads to an expression for the mean fall velocity that makes physical sense. The coefficients in the proposed formula were determined with laboratory data of uniform sediment, and it is verified by field data measured from alluvial rivers. The concept of instantaneous equilibrium was proposed so that applicability of the formula extended to estuaries. The results show that the present formula performs well in conditions of laboratories, rivers, and estuaries. This can provide a key parameter or bottom boundary condition for two-dimensional/three-dimensional mathematical models of nonuniform sediment.