DUNE DISTRIBUTION ALONG THE LAURENTIAN GREAT LAKES: THE EFFECTS OF WIND AND WAVES

State and provincial databases were used to map the distribution of dunes along the 15,700 km shoreline of the Laurentian Great Lakes. Local geology controls the availability of sand and, hence, exerts the primary control on the distribution of sand dunes. Given adequate sand supply, the development of dune complexes is controlled by onshore wind and wave energy. Data from airport or NOAA meteorological stations were used to construct Fryberger and Dean (1979) drift potential diagrams for 41 locations along the coast. “Prevailing” winds in the region are from the southwest, and the most extensive dune complexes (eastern shores of Lake Michigan and Lake Huron) occur where westerly onshore winds intersect sandy shorelines. Most strong wind events in the region are associated with extratropical cyclones. Local winds rotate as cyclones pass through the region and often depart from the prevailing westerly direction. Where onshore storm winds are amplified by long fetch due to lake orientation, there is high onshore drift potential, even along northern, southern or western shores. Hence dunes develop where there is adequate sand supply. Erosion associated with storm waves can locally increase sediment supply. Wave roses along with dominant wave period histograms were derived for Great Lakes shore lines from NOAA buoys in order to further understand this effect.