Impacts of Freeze-Thaw on Cliff Recession at the Calvert Cliffs in Maryland

Abstract

The Calvert Cliffs, which form much of the western coastline of the Chesapeake Bay in Calvert County, Maryland, are actively eroding and destabilizing, creating a critical condition for many homes in close proximity to the slope's crest. In past studies, it has been identified that where waves directly interact with the toe of the slope, wave action controls recession; however, where waves do not regularly interact with the slope toe, freeze-thaw was identified as controling recession rates. This preliminary phase of the project analyzed the recession rate at two study sites along the Calvert Cliffs that are not directly affected by waves. While waves do have the role of removing failed material from the toe, in these regions freeze-thaw is believed to be the dominant factor driving cliff recession. Past recession rates were calculated using historical aerial photographs. These rates were analyzed together with historical temperature data. The investigation found that the recession rate has a positive correlation with freeze-thaw cycles at one site, while no such relationship was observed at the other site, indicating further investigation is needed.