Two-layer hydraulic exchange flow through the Burlington Ship Canal

Abstract

The exchange flow through the Burlington Ship Canal connecting Hamilton Harbour with Lake Ontario is investigated, using a two-layer internal hydraulics model. The summer exchange features an upper layer of polluted Harbour Water flowing from the harbour into the lake, whereas a lower layer of fresh Lake Ontario Water flowing from the lake into the harbour. We predict this exchange, taking into account the effects of both friction and barotropic forcing of multiple frequencies. Predictions of density interface and volume flux compare well with experimental and field data. The interface varies non-linearly with distance along the canal, with and without barotropic forcing. Our results indicate that the exchange flow is highly frictional. The barotropic forcing comprises oscillation modes of different frequency; these individual forcing modes cause the interface and layer velocities to fluctuate significantly in time, but their influence on the time average flows through the canal is minimal.