RUBBLE RIDGES

ILLINOIS BEACH STATE PARK, IL

WATERFRONT | RESILIENCE/CLIMATE ADAPTATION | MONITORING

Status: Constructed, Ongoing Maintenance

Awards:
ASLA Honors Planning Award (2020)


The Rubble Ridges are an innovative coastal resilience pilot project constructed in 2021 at Illinois Beach State Park and Hosah Park in Zion, IL.  This project, developed from our team's research, aims to protect rare terrestrial habitats from accelerated coastal erosion by incorporating in-water habitat features. The project was a collaborative effort between the Illinois Department of Natural Resources and the USACE Chicago District, funded by the EPA Great Lakes Restoration Initiative and monitored by NOAA.

Illinois Beach State Park, the state’s last beach-ridge shoreline, provides recreational and economic opportunities at Illinois’s northern border along Lake Michigan. It hosts a dynamic ecosystem, with prickly pear cactus in drier areas and marshlands in swales. The beach-ridge and interdunal wetlands offer critical habitats for many species of plants and animals, including several threatened or of state concern.

To protect these rare habitats and the recreational and economic opportunities along the coast, we aimed to design a system that leverages natural processes to create aquatic habitats and slow erosion without disrupting longshore sediment transport. This project seeks a middle ground between expensive, intensive capital projects like armoring and breakwaters, and softer, less costly but more maintenance-intensive projects like annual beach nourishment. It can work in conjunction with these methods or independently, broadening the range of coastal protection strategies. Although large water level fluctuations are part of the natural processes in this coastal ecosystem, near record-high levels of Lake Michigan from 2018-2021 exacerbated erosion, threatening public access, critical infrastructure, and important ecological areas.

The Rubble RIdges' underwater ridges are more adaptive to natural systems and less visible than vertical breakwaters. A three-ridge system, as opposed to a submerged breakwater, is easier to construct, uses smaller stones, and provides potential in-water habitats for fish. The project's objective is to reduce wave energy in the nearshore environment without disrupting longshore sediment movement. Erosion in this landscape is both a critical threat and a fundamental process. Our concept is based on the paradox that we could achieve better long-term outcomes with less control by working with natural erosion processes.

We combined physical and computational modeling to test concepts through a nonlinear, iterative, yet rapid process. Modern computational modeling opens new design possibilities, but we still value testing concepts with actual water and sediment to simulate conditions on a small scale. We tested different submerged ridge variations against physical simulations of daily, storm, and post-storm conditions, and used computational modeling to calibrate the size, scale, and positioning of the design before installation.

The site will be monitored before and after implementation to assess the effectiveness of this lower-cost, lower-impact, and rapid-response intervention. The project aims to provide valuable insights into low-impact interventions, potentially serving as a model for similar coastal areas facing erosion challenges. Michigan State University’s Theuerkauf Lab and ISGS will conduct high-resolution aerial photography, single-beam surveys, and multi-beam surveys to monitor the onshore and offshore areas, determining the size, shape, location, and elevation of the land, vegetation, and shoreline position for five years post-placement.


Learn more:
Press:


    Client: Great Lakes Protection Fund

    Collaborators:
    Illinois Department of Natural Resources- Coastal Program
    Illinois State Geological Survey
    Illinois Natural History Survey
    Great Lakes Resiliency Initiative
    National Oceanic Atmospheric Administration
    USACE Chicago District
    Zion Park Service


    return to WORKS
    PROOF PROJECTS LLC