A numerical model for water level oscillations in the St. Lawrence estuary, Canada Part I: Tides

Abstract

A two‐dimensional time‐dependent nonlinear tidal model was developed for the St. Lawrence estuary, with two open boundaries. This model is a substantial improvement over two earlier models which did not include the nonlinear terms. The model is run simultaneously, to hindcast the tide on any particular day, using as boundary conditions real data for the five important constituents, namely M₂, S₂, N₂, K₁, and O₁. Coamplitude and cophase diagrams were constructed and compared with known shore‐based gauge observation. This comparison revealed that the model performs quite satisfactory. Further calibration was then carried out by adjusting the bottom friction coefficient. Such a calibration is necessary before the model can be used to simulate tsunami generation and propagation in the estuary. The total water level during the occurrence of a tsunami should include not only the tsunami amplitude, but also the interaction of the tsunami with the tide.

Keywords:

• tide
• modeling
• St. Lawrence estuary
• Canada