Hydrodynamic and sediment suspension modelling in estuarine systems: Part I: Description of the numerical models

A fully-3D finite difference baroclinic model system for hydrodynamics and fine suspended sediment transport is described. The hydrodynamic model is based on the hydrostatic and Boussinesq approximations, and uses a vertical double sigma co-ordinate with a staggered grid and a semi-implicit two-time level scheme. In addition to the momentum and continuity equations, the model solves two transport equations for salt and temperature and an equation of state to include the baroclinic effects. The simulation of cohesive sediment transport processes is performed solving the 3D-conservative advection–diffusion equation, in the same grid used by the hydrodynamic model. Flocculation, erosion and deposition of sediments on the bottom are represented by means of empirical formulations parameterized by field data. The models were tested and calibrated by simulating tidal flows and suspended sediment transport in several estuaries (two applications are described in Part II). The results show good agreement between the numerical predictions and the corresponding field measurements.