Improving coastal resilience planning with respect to long-term water level fluctuations by examining decadal coastal profile behavior at sandy, harbor filet beaches along Lake Michigan in the Great Lakes of North America

Abstract

Resilient planning for coastal hazards requires an understanding of both short-term and long-term coastal change dynamics. Numerous studies have been conducted throughout the Great Lakes of North America on processes and responses associated with short-term coastal changes, such as storms and seasonal fluctuations in lake level; however, few datasets exist that can capture long-term coastal morphodynamics in this region. Lack of data and knowledge creates a barrier for accurately modeling future coastal change, which underpins proactive coastal management. This is particularly problematic at sites adjacent to coastal infrastructure, such as those near harbors. To address this, we utilize a 32-year record of coastal profile change from several sites along the Lake Michigan shoreline of Michigan to examine profile evolution in response to changing lake levels and human disturbance. These data reveal that coastal sites without shoreline armoring can recover from erosive high lake level phases if lake level remains low for an extended period. However, if sites are armored, or if future climate conditions result in more frequent or more extreme lake level fluctuations, full recovery of the coastal profile is unlikely. Managers and decisionmakers can utilize this information to evaluate their site conditions and proactively plan for future coastal changes.