Physical Model of Niagara River Discharge

Development of a physical model study for the Niagara River discharge into Lake Ontario is described. The model is designed on the basis of (distorted) Froude and Rossby similarity and the results demonstrate clearly the effects of rotation on the flow. Important features of the plume are shown to be reproduced by the model, including its anticyclonic (right-turning) flow and the subsequent formation of a near-shore current along the southern coastline. A scaling analysis of the integrated longitudinal momentum equation is suggested as a framework for analyzing this type of flow. This analysis considers three regions of the flow: (1) a near-field, where inertial forces are balanced by pressure and bottom drag; (2) an intermediate-field where the balance is between inertia and buoyancy; and (3) afar-field characterized by nearly geostrophic flow (balance between buoyancy and rotation). This scheme is then tested against conditions characteristic of the Niagara River discharge during spring flows and also with observations from the physical model tests, showing reasonable agreement. One particular result of interest is that the distance at which rotation starts to turn the flow scales approximately with the internal Rossby radius. Results of the study help to distinguish between the relative effects of buoyancy and rotation.