In summer, the temperature difference between Hamilton Harbour and Lake Ontario drives a
two-layer exchange flow through the Burlington Ship Canal. Warmer Hamilton Harbour
water forms the upper layer in the canal before floating out onto the surface of Lake Ontario,
while cooler lake water forms the bottom layer in the canal prior to sinking into the harbour's
hypolirnnion. During periods of exchange flow, large amounts of water are exchanged
between the harbour and the lake, thus an understanding of this phenomenon is necessary to
determine the water quality of either body. In the summer of 1996, an extensive field study
was conducted to obtain a better understanding of exchange flow dynamics in the Burlington
Ship Canal.
Acoustic Doppler Current velocity Profiler (ADCP) and Conductivity-Temperature-Depth
(CTD) profiles measured during 5 drifts along the canal from a boat on July 25, 1996 were
analyzed in the present study. Differential Global Positioning System (DGPS) was employed
to determine surface location within the canal. Density in the canal was calculated from
temperature and conductivity using a lakewater equation of state. A hyperbolic tangent
function was fit to each of the velocity and density profiles in the ship canal. This fit provided
a convenient way of characterizing the density and velocity of each layer, the interface
location, and thickness of the interface. Flows into and out of Hamilton Harbour were
estimated by integrating the velocity profiles with respect to depth. By forcing control
locations at the ends of the Burlington Ship Canal, a line was calculated as an initial estimate
of the interface profile using the measured flow for each layer and the density difference. As a
first approximation, the line provides a reasonable fit to the data. However, unsteadiness in
the flow limits the validity of the concept of hydraulic control and other aspects of steady 2-
layer hydraulics. Predictions of the interface fit should be extended to account for unsteady
effects. In addition, barotropic and frictional effects should be considered.
All of the drifts, except for one where mixing was caused by the passage of a large ship
through the canal rather than exchange flow, exhibit similar mixing patterns. The bulk
Richardson number associated with velocity, J8 = 0.30, and the bulk Richardson number
associated with density, Jη = 0.25. These values compare very favourably with published
values of J from theoretical, numerical and experimental work. In the Burlington Ship Canal,
mixing may be predicted once the background flow is known. Unfortunately, steady, 2-layer
hydraulics cannot provide an accurate estimate of the background flow. [Certain scientific formulae used in this abstract could not be reproducted.]
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/8220 |
| Date | 11 1900 |
| Creators | Greco, Susan Lavinia |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Relation | UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/] |
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