Rotational water movements in western Lake Erie

Abstract

SummaryPrevious studies of the currents in western Lake Erie have been based on one method of investigation, drift bottles or drift cards. The studies revealed a gyral around Pelee Island. However, later evidence indicated that a much larger area was involved. The hypothesis of a net rotary movement of water in the western basin was confirmed. The force which is believed to produce the rotation is the primary longitudinal seiche which becomes a derived wave in the western basin. The island region acts as a spill-way for the overflowing seiche. The present study employed five different simple techniques to establish the pattern of water movements. 1. Lake level records at three strategic locations in western Lake Erie showed a rise and fall of water level, progressing in a clockwise direction around the basin.2. Wind generated surface currents move to the northeast under the prevailing southwest winds. This was shown by the movement of drift cards. The prevailing southwest winds contribute to the rotation of water in the western basin.3. Isotherms are distorted by the seiche action and the distortion showed a definite movement of water westward through the South Channels, and a northward movement through the island region. Net outflow occurred only through the Pelee Passage.4. Light transmission data, used as a measure of turbidity, showed the deflection of turbid water toward the north and an ingress of clear water from the east. Extremely turbid water was shown to enter the western basin from the Maumee River. The pattern of turbidity in western Lake Erie corresponds closely to the current pattern indicated by the distortion of isotherms.5. The net flow of water into and out of the western basin has been determined using direct current measurements. The net inflow through the South Channels was 57,600 cfs. The inflow plus the average river discharge into the western basin of 184,000 cfs was moved out of the western basin through the Pelee Passage. The net outflow through the Pelee Passage was 209,300 cfs.