Two-dimensional vertical model for salt intrusion in estuary

There have been few studies of salt wedge instability under the influence of tidal motion and of the behavior of interfaces and interface instability conditions when tidal waves propagate up the rivers. To clarify these phenomena, it is necessary to use a vertical two-dimensional or three-dimensional numerical model for analysis. In addition, the modeling of tidal wave effects at the upstream boundary is an important issue. Numerical analysis is carried out on the salt intrusion caused by the propagation of a tidal wave, with two-dimensional Reynolds and diffusion equations used as the governing equations under a boundary condition that allows tidal waves to pass through the upstream boundary. It was possible to explain the temporal variation of surface elevation as well as the vertical structure of flow and salinity during hood or ebb tides in the estuary. The location of isohalines changes periodically with variations in tide and depending upon the Froude number.