Mathematical model study of tidal circulation in Tolo Harbour, Hong Kong: development and verification of a semi-implicit finite element scheme

Abstract

The tidal circulation in Tolo Harbor, Hong Kong, is computed by a newly developed semi-implicit finite element model. The accuracy and efficiency of the unconditionally stable time-stepping scheme are confirmed by a detailed Fourier analysis and extensive tests against analytical solutions of long wave propagation in basins of varying lateral topography and bottom bathymetry. With M//2 tidal forcing at the seaward (open) boundary, the model is capable of reproducing the near standing wave and characteristic circulation in the bay. Computed velocities and elevations are also validated against good quality field data in a verification study. It is found that accurate input tides at the seaward boundary of the model are needed to simulate the propagation of the complex shallow water tides in the study area. The correctly simulated tidal phase lag between the open boundary and inshore is found to be at variance with data in published tide tables.