The Relationship between Great Lakes Water Levels, Wave Energies, and Shoreline Damage

Abstract

The latter half of the twentieth century can be characterized as a period of rising water levels on the Great Lakes, with record high levels in 1974 and 1986. Concurrent with these periods of high water level are reported periods of high shoreline damage and property loss. Water levels of the Great Lakes are determined by precipitation, evaporation, river outflow, and groundwater inflow, while wave energy is primarily a function of wind speed, duration, and fetch. A comparison between a recently completed long-term (1956–87) wave climate hindcast and historical lake levels for the Great Lakes shows a strong correlation between periods of high wave energy and high lake levels. Statistical comparison of these two time series indicates an approximately constant correlation from +24 months to −6 months, around a zero lag/lead. The causational link between increasing lake levels and more intense wind-generated waves appears to be related to significant changes in the climatology of Great Lake's basin cyclones....