HYDRODYNAMIC DATA FOR WESTERN-PORT, VICTORIA

Hydrodynamic data were obtained in Western Port to provide information about the tides and flow conditions and to estimate the bed friction coefficient and evaluate other constants necessary for calibrating a mathematical hydrodynamic model. The data collection and analysis program included meteorological data to compute wind shear at the water surface; tidal amplitude and phase from tide gauges placed at eight locations within the bay; current speed and direction profiles across seven traverse lines bounding major segments of the bay; drogue tracking over various ebb cycles in the Western and Eastern Entrances; and dye-dispersion studies during conditions of flood and ebb phases of spring and neap tides. Dye-dispersion studies were actually carried out in 1968 and the data have been used in this study. The lunar semidiurnal tide is the principal driving mechanism for the waters of the bay. Tidal range increases towards the head of the bay to a maximum of about 1.3 times the range at the entrance. Tidal lag at the head of the bay is about 2 hours. In most channels the depth-mean velocity attains a maximum of 0.6 m/sec; however, local topographic effects have a strong influence on both the velocity field and tidal lag. Under pure tidal motion there appears to be a clockwise circulation around Phillip Island and possibly French Island. Winds stronger than 10 m/sec are related to anomalous tides throughout the bay and also appear to exert a significant influence on the net circulation around the islands. © 1979.