Author(s): Junichi Yoshitani; M. Levent Kavvas
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Keywords: No Keywords
Abstract: This paper is about derivation of a stochastic transport equation for the longitudinal migration of a conservative pollutant by unsteady-nonuniform river flows at the scale of a river reach. First, a cross-sectional-area averaged transport equation is derived by integrating the point mass conservation equation over a flow-cross-sectional-area and introducing Fickian diffusion. Second, in order to express stochasticities of flow velocity, lateral inflow, and dispersion at the scale of a river reach, the local-scale cross-sectional-flow-area averaged transport equation is considered as a stochastic differential equation at river reach scale. Third, a deterministic transport equation for the prediction of the evolution of mean pollutant concentration over several kilometers of a river reach is obtained. It is noted from the equation that the nonuniformity of the flow field modifies the mean path of the pollution particles.
Year: 1997