Barrier Island Dynamics Using Mass Center Analysis: A New Way to Detect and Track Large-Scale Change

A geographic information system (GIS) was used to introduce and test a new
method for quantitatively characterizing topographic change. Borrowing from classic
Newtonian mechanics, the concept of a body’s center of mass is applied to the geomorphic
landscape, and the barrier island environment in particular, to evaluate the metric’s potential
as a proxy for detecting, tracking and visualizing change. Two barrier islands along
North Carolina’s Outer Banks are used to test this idea: Core Banks, uninhabited and
largely-undeveloped, and Hatteras Island, altered by the presence of a protective dune
system. Findings indicate that for Core Banks, the alongshore change in the center of
mass is in accord with dominate littoral transport and wind conditions. Cross-shore change
agrees with independent estimates for the island migration rates. This lends credence to our
assertion that the mass center metric has the potential to be a viable proxy for describing
wholesale barrier migration and would be a valuable addition to the already-established
ocean shoreline and subaerial volume metrics. More research is, however, required to
demonstrate efficacy.