Brine discharges into shallow coastal waters with mean and oscillatory tidal currents

The development of a mathematical model on the cumulative effects due to brine discharges into shallow coastal waters with a flat seabed is conducted in this study. The model incorporates the effects of tidal currents, which are commonly encountered in the natural coastal environment. The tidal currents are represented by a small constant component, V (normally referred as residual or drift current), plus a periodic part, U-0 sin omega t. Anisotropic eddy dispersivities in the alongshore and cross-shore directions are also incorporated. The convergence to the quasi-steady state for the salinity excess due to the continuous brine input has been studied for the first time. The application of the mathematical model to assess a hypothetically practical discharge is also performed. Model predictions for representative velocity ratios of v (=V/U-0) are obtained. In general, the placement of the outfall further offshore has been shown to reduce the shoreline impact as expected. A comparison of the results between constant and time-dependent dispersivities has been conducted. (C) 2008 International Association for Hydraulic Engineering and Research, Asia Pacific Division. Published by Elsevier B.V. All rights reserved.