A Numerical Model Simulation of Cross Scale Interaction Between River Plume And Coastal Flows

In this study, an effective three-dimensional numerical model is used for the simulation of both barotropic and baroclinic processes across river-to-ocean scales. The governing equations of the model are based on the hydrodynamic equations and coupled with scalar transport equations. An unstructured grid system is adopted for better fitting of the river banks and coastal shorelines, and the staggered definition for different variables is used to avoid chess accumulated error. Consistent finite volume schemes are adopted to assure mass as well as volume conservations. A semi-implicit Eulerian-Lagrangian algorithm is used to solve the shallow water equations for enhancing computational efficiency. The model was applied to the Danshuei River estuarine system and its adjacent coastal sea, including its three major tributaries: the Tahan Stream, the Hsintien Stream, and the Keelung River. Comparisons between elevations of surface water for both the observed and the predicted results appear to be well. Real time simulations of river plumes were compared with satellite images on the dates during high river flow conditions when the turbid river waters are detectable from space. It is noted that the swaying trend of the model predicted river plume is consistent with the satellite image, which delineates the extent of turbid river water under the high river flow condition obtained on corresponding day.