Erosion on the Illinois coast of Lake Michigan is a significant economic burden for municipalities trying to preserve the recreational value of beaches and coastal infrastructure. Loss of the shoreline also endangers sensitive ecosystems and habitats. At the same time, sand accumulation along harbors results in dredging costs and adversely affects recreational and commercial boating.

These are the reasons why scientists are interested in mapping coastal sand distributions and patterns of movement. Researchers in the ISGS Coastal Geology group deploy various technologies and methods to better understand the complex processes driving morphologic changes across beach, dune, wetland, and estuarine systems. Field data inform models of coastal change and help coastal managers best preserve Illinois’ coastline through science-based decisions.

Technical support

ISGS researchers provide technical support to the Illinois Department of Natural Resources’ Coastal Management Program (CMP). Data products include models of shoreline evolution and habitat vulnerability, which have helped inform shoreline-protection decisions at Illinois Beach State Park. This site is home to the last remaining natural beach shoreline areas in Illinois, which are threatened by ongoing coastal erosion. Shoreline losses have implications for many endangered plant and animal species, particularly those inhabiting the rare coastal wetland habitat types that exist there. Rates of erosion and habitat loss increased dramatically with the rising lake-level conditions of 2013–2020. Ongoing ISGS efforts to understand the associated dynamics of sediment transport are not only an important component to understanding and preserving valuable coastal ecosystems, but they also inform the evaluation of coastal carbon budgets and hydrologic models.

Research methods

Studying sediment dynamics and linking these to hydrodynamic processes, such as strong storm events, provide a context for changes to the coastal environment, its habitat distributions, and damage to recreational facilities and other infrastructure. The ISGS Coastal Geology group evaluates coastal change over a variety of temporal scales, from studying the impacts of individual events on the coastal zone to assessing multi-decadal patterns of change.

Historic shoreline and coastal habitat changes have been reconstructed from aerial photographs dating as far back as the 1930s. Drone and high-precision Global Positioning Systems (GPS) technologies are used to create high-resolution digital terrain models of the beach environment. Monitoring beach sites by repeat surveys provides information for elucidating the cause-and-effect relationships within the interplay between lake hydrology (e.g., waves and currents), shoreline infrastructure, and beach evolution.

The researchers also deploy a 27-foot research vessel to map lake-bottom depths using sonar technology. Repeat surveys thereby allow the tracking of sand by way of mapping patterns in lake-floor elevation change.

Aside from actively monitoring portions of the Illinois Coast for topographic and bathymetric changes, ISGS coastal scientists collect sediment samples and image the subsurface using geophysical methods, such as ground-penetrating radar. These efforts are aimed at reconstructing coastal depositional architectures, which tell the story of the region’s geologic evolution. Such initiatives help scientists understand groundwater flow, the history of human occupation, and past climate changes and also provides a context to better predict future environmental changes.

Projects

Recent and ongoing projects include:

• Sustainable nearshore management solutions to prevent critical habitat loss at Illinois Beach State Park
• Quantifying the annual carbon budget from a rapidly eroding freshwater coastal wetland using field and model data
• Mapping geomorphic changes along Great Lakes coastlines with small, unmanned aerial systems
• Coastal geomorphic response to seasonal lake level rise in the Laurentian Great Lakes
• High-resolution monitoring of Illinois Lake Michigan waves and currents to improve coastal models and public safety
• Sediment transport associated with nearshore sediment placement
• Bluff retreat and nearshore response to rising lake levels
• Mapping the subsurface architecture and age structure of the Zion Beach-ridge Plain using reflection geophysics and sediment core data
• Evaluating the role of coastal infrastructure design on Chicago beach response to lake-level changes from historical aerial photographs and coastal LiDAR datasets
• Mapping sediment distributions across the Chicago nearshore zone using marine seismic surveying and coring methods
• Assessing the impacts of winter ice on the beach system and addressing the potential for littoral sediment losses using precision surveying methods

Data from various projects on coastal geology are available on the ISGS Illinois Geospatial Data Clearinghouse. Drone data collected from the Illinois State Beach Park are available in the clearinghouse at this location. Two story maps, A Vanishing Coast and A Dynamic Shoreline, illustrate from a drone’s viewpoint how researchers monitor the coast at Illinois State Beach Park.