Characteristics of the Exchange Flow of the Bay of Quinte and Its Sheltered Embayments with Lake Ontario

Jennifer A Shore

doi:10.3390/w13131857

Abstract

The nature of the exchange flow between the Bay of Quinte and Lake Ontario has been studied to illustrate the effects of the seasonal onset of stratification on the flushing and transport of material within the bay. Flushing is an important physical process in bays used as drinking water sources because it affects phosphorous loads and water quality. A 2-d analytical model and a 3-dimensional numerical coastal model (FVCOM) were used together with in situ observations of temperature and water speed to illustrate the two-layer nature of the late summer exchange flow between the Bay of Quinte and Lake Ontario. Observations and model simulations were performed for spring and summer of 2018 and showed a cool wedge of bottom water in late summer extending from Lake Ontario and moving into Hay Bay at approximately 3 cm/s. Observed and modelled water speeds were used to calculate monthly averaged fluxes out of the Bay of Quinte. After the thermocline developed, Lake Ontario water backflowed into the Bay of Quinte at a rate approximately equal to the surface outflow decreasing the flushing rate. Over approximately 18.5 days of July 2018, the winds were insufficiently strong to break down the stratification, indicating that deeper waters of the bay are not well mixed. Particle tracking was used to illustrate how Hay Bay provides a habitat for algae growth within the bay.

Highlights

Freshwater runoff during heavy rain events and the spring melt naturally flushes bays and lakes but this flushing can often bypass sheltered embayments
Previous observations of the hydrography in middle bay showed that during the summer months when there is a thermocline above the sill in the Glenora Gap, the surface flow is outward through the Gap toward Lake Ontario and there is a backflow at the bottom [5]
Observations and modelling efforts have been used to show that the nature of the flow in middle bay is generally two-layered in summer, with significant inflow from Lake Ontario at depth

Summary

Introduction

Freshwater runoff during heavy rain events and the spring melt naturally flushes bays and lakes but this flushing can often bypass sheltered embayments These flushing events typically bring cooler, more oxygenated water and phosphorus attached to suspended sediment, which results in hydrographic changes and potential algae and bacterial growth due the phosphorus. Models of TP budgets developed for the Bay of Quinte generally assume a two-layer model at the mouth of the bay east of the Glenora Gap while assuming that middle bay, which is shallower, is only one layer and is well mixed [3,6].

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Results

Conclusion