SHORELINE CLASSIFICATION AND EROSION CHARACTERIZATION ON THE ILLINOIS COAST OF LAKE MICHIGAN USING SYNTHETIC APERTURE RADAR

Among the most dynamic sections of the Laurentian Great Lakes is a 450 km stretch of shoreline at the southern extent of Lake Michigan, which runs along the coast of Illinois. The great expanse of open water north of this area allows for the buildup of energy that is then released along the Illinois coast through near-shore currents, waves, and winds resulting in high rates of shoreline erosion. Shoreline erosion can lead to dangerous and costly damage to coastal infrastructure. The Illinois coast of Lake Michigan shares this in common with coastal environments around the world, inland and oceanic alike.

The traditional methods for measuring shoreline change with fine spatial or temporal resolution tend to be labor-intensive and may be difficult to deploy in the time immediately surrounding large erosional events such as storms or ice formation. Additionally, traditional shoreline measurements often rely on ground-based measurement points that are subject to erosion, accretion, or other modes of change over time, particularly over the winter. In such a situation, remotely sensed data may provide complementary and even improved data quality and density. Optical satellite data has been used extensively to monitor shoreline change, but its use can be limited due to cloud cover, particularly during winter months. The lack of data coverage from optical satellites during winter is particularly problematic as there are many open scientific questions about the erosional dynamics along the shoreline of high latitude bodies of water in response to ice.

We use Synthetic Aperture Radar (SAR) data to delineate a section of shoreline in Illinois Beach State Park, over the course of several years and through all seasons to investigate seasonal variations in erosion. The shoreline at our study site has experienced more than a hundred feet of retreat in the past decade resulting in potentially significant impacts to wetland ecology and park infrastructure. Using SAR data, we classify the land-water boundary through time and use this classification to establish erosion trends at this site and the surrounding area to investigate the erosional dynamics. SAR data analysis allows us to extend the spatial coverage of previous ground-based measurements and complements existing optical satellite data, which are used to confirm our findings.