Analytical Modeling on Dispersion of Nonconservative Pollutant on a Step Increase in Depth Flow

Abstract

Coastal wastewater-discharged effluents are likely to consist of pollutants with different dispersion and decay rates that vary with water depth. Mathematical models using a two dimensional advection-diffusion equation with a point source are presented to study the effects of a cross-stream sudden depth change and decay on mixing and dispersing steady discharge of non -conservative effluents. Analytical solutions are illustrated graphically by plotting contours of concentration, showing snapshots of discharged effluent plumes spreading. The shapes of effluent plumes across the cross-stream depth discontinuity line are significantly different, and thus the concentration at the discontinuity line is formulated to measure how much has effluents dispersed into or out of the shallow nearshore region.