Finite-Difference Modelling for a One-Dimensional Rectangular Estuary

A numerical method for the analysis of dispersion of pollutants in a one-dimensional rectangular estuary within a tidal cycle is presented. The finite-difference method is used to obtain a solution for the partial differential equation. An explicit scheme using multi-step procedure is adopted for solving the problem. It is shown that an analytical method is capable of predicting the dispersion of a slug load in the estuary as long as the effect due to the open boundary is negligible. However, the finite-difference method is required to study the dispersion effect of a continuous or variable pollutant source subjected to variable tidal velocity. The model developed is also applied in determining the effect of salinity intrusion within a tidal cycle due to different fresh water flows.