ABSTRACT: Calculated wave base in relation to the observed patterns of sediment deposition in northeastern Lake Ontario.

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Abstract

Wave base was calculated from standard formulae utilizing the concept of effective fetch for a portion of northeastern Lake Ontario. Effective fetch, shown to depend significantly on the shape of the water body, varies from more than 70 km in the exposed waters of Kingston Basin to less than 5 km in the interisland area. Wind speeds of 30, 60, and 90 km/h were used in the calculations, representing, respectively, measured velocities of moderate winds experienced during about 10% of the open water period, rare winds but that are sufficiently frequent to be important during the sedimentary history of the lake, and winds that do not occur or occur so infrequently as to have little impact on sedimentary processes. At 30 km/h calculated wave base ranges from 3 to 0 m between protected and open water; at 60 km/h the range is from 6 to 20 m, and at 90 km/h the range is from 8 to 29 m. Comparison with measured sediment cover on the lake floor determined from subbottom acoustic survey shows better agreement with the pattern predicted using 60 km/h winds than to patterns derived from higher and lower wind speeds. The method offers a simple way of assessing the reworking of lacustrine sediment by waves and the focusing of sediment in areas of deeper, quieter water.

Bibliography of Canadian Geomorphology