Mass Exchange Between Hamilton Harbour and Lake Ontario

The mass exchange between Hamilton Harbour and Lake Ontario waters through the Burlington Canal is important for estimating the dissolved oxygen budget of the harbour. Lake-harbour exchange is caused by either the oscillatory flow in the canal during isothermal conditions or the densimetric flow during thermal stratification. During the study period (September 1975), the canal water was found to be quasi-isothermal; consequently oscillatory flow existed. A computational method was developed to estimate the exchange based on excursion distance travelled for each limnological episode, and the final flow in each direction was checked with dissolved solids budget. An average of 2.04 × 10⁶ m³.d^?1 (24 m³.s^?l) of harbour water is estimated to flow into the lake, while 0.73 × 10⁶ m³.d^?1 (8 m³.s^?1) of lake water flowed toward the harbour during September 1975. This accounts for the total and net daily exchange of 0.98% and 0.48% of harbour volume, with net exchange being toward the lake. The total and net exchanges were respectively 8 and 4 times the natural drainage during the study period. On a monthly average, more water leaves than enters the harbour. The lake-harbour exchange is considered important for maintaining and even improving the existing harbour water quality. The harbour dilution factor was estimated as 0.0019 per day for the present study.