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On the physical oceanography of Burrard Inlet and Indian Arm, British Columbia

University of British Columbia

Measurements of the distributions of temperature, salinity and oxygen in Burrard Inlet and Indian Arm, British Columbia from May 1974 to October 1975 have been analysed to determine features of the large scale circulation in this system. Observations at roughly four-week intervals were supplemented by serial CSTD casts taken over intervals of a few hours, and by 93-day records of near-bottom currents, temperature, and salinity on the Indian Arm sill. Short-term tidal fluctuations in property distributions have been shown to be small compared to seasonal changes. Circulation in the Burrard Inlet - Indian Arm system is basically estuarine: relatively fresh surface waters normally flow down the inlet overlying more saline waters which enter from the Strait of Georgia. Turbulent mixing associated with estuarine and tidal flow through the shallow constrictions at both First and Second Narrows yields surface waters between the narrows which are more saline and cooler than those which would be found in a simpler estuarine environment. In a complementary sense, bottom waters are fresher and warmer. Significant exchange and overturn of deep water in Indian Arm was recorded between October 1974 and April 1975. Intruding waters were shown to have originated west of First Narrows. In one instance exchange of at least 80% of the volume of the Arm, over an interval of 33 days, was inferred from property distributions, compared to exchange estimates of 111% and 74% deduced from the current meter record for the same event. Exchange was shown to be intermittent, with fresh water runoff volume into Indian Arm, tidal mixing (particularly at Second Narrows) and density of Georgia Strait water being identified as some of the controlling factors.

Text

2010-03-10

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http://hdl.handle.net/2429/21731

Oceanography

University of British Columbia

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