ON RESIDUAL TRANSPORT IN SHALLOW TIDAL BASINS

Abstract

In the paper the influence of some physical and numerical effects on computations of residual transport in shallow tidal basins is analysed. Investigations deal with: i) the Coriolis acceleration, ii) the specification of the tidal forcing, iii) the diffusion coefficient, iv) a time weight in a standard implicit numerical scheme. The analysis has been carried out by means of intratidal mathematical models with reference to three schematic basins, with the tide being the only forcing of the system. These are typical conditions in which critical environmental events like anoxia occur. Usual assumptions in mathematical modeling of 2D flows in shallow basins regarding the above effects are tested both in the short and long term. The different importance of that effects depending on both the time scale of processes and the basin morphology is shown. Results are presented in terms of turbulence-time-averaged circulation patterns, Lagrangian residual circulation patterns, distributions of relative differences induced in the latter by including or not the investigated effects, and convection-dispersion of a passive solute.