Comments:
Dynamic analysis time series of current and sealevel measurements at a location near the middle strait shows that the principal force balance is between the frictional stress and the pressure gradient frocing (swift and Brown, 1983). Hence, the kinematic assumption is confirmed. The computational grid, named gbriv for the Great Bay Estuary system is created using linear equilateral triangles fitted to the shoreline boundary. There are 10223 and 18710 elements. The bathymetric depth contour reveals a center channel running north to south and tidal flats in the southern part of the domain.

M2 tidal forcing is specified as a Dirichlet elevation boundary condition across the northern inlet boundary at the top. The amplitude is 0.83m. The simulation was started with fluid at rest and was terminated after five M2 tidal period (62.10hrs). The simulation setup is given below. All the simulation parameters are summarized in Table below.

Comments:
Time history of the total fluid volume and the cumulative transport across five selected transects as shown in gbriv show the system establishes a dynamic equilibrium rapidly, and mass conservation is thereafter maintained throughout the simulation after the initial tidal period. The maximum normal velocity across the transects increases then decreases as one moves southward with maximum level across the middle strait, while the normal transport across the same transects decreases to maintain mass conservation. Both quantities decreases sharply at the two tidal flat cuts. It is noticed that asymmetry exists between flood and ebb.

Residual transport:

Comments:
Residual transport vectors are directed inward from the top inlet along the shore boundary and the shoreline tidal flats down the upper channel into the lower bay and return outward throuh the deeper channel. gbriv-resq.gif shows there is a counter clockwise gyre around a pit at the middle part of the channel just inside the inlet boundary. This causes residual transport out of the inlet at its middle portion. Simulation results indicates that the residual bottom stress is intensified within the channel especially in the vicinity of the upper boundary inlet and the middle narrow strait. With M2 forcing, the residual sediment transport is observed to be the most intense near the narrow strait directed southward.

Comments:
The above transient solutions are numerically well-behaved and appear to describe the realistic dynamics of the tidal flooding and dewatering process in this complex domain.