Illinois Beach State Park

Overview

Illinois’s last beach-ridge shoreline, Illinois Beach State Park offers recreational and economic opportunities at the state’s northern border along Lake Michigan. It’s home to a dynamic ecosystem where prickly pear cactus blooms in drier areas and swales sustain marshlands. The beach-ridge and interdunal wetlands provide a rare and critical habitat for many species of plants and animals, including multiple threatened or state concern species.

The valuable Beach Ridge Plain at the Illinois Beach State Park is eroding at an unprecedented rate, due primarily to climate shifts and the associated increase in storm activity.

The valuable Beach Ridge Plain at the Illinois Beach State Park is eroding at an unprecedented rate, due primarily to climate shifts and the associated increase in storm activity.

The western shoreline of Lake Michigan exhibits unique habitats and formations due to the slow moving series of coastal dunes, creating the Beach Ridge Plains that characterize this region.
The western shoreline of Lake Michigan exhibits unique habitats and formations due to the slow moving series of coastal dunes, creating the Beach Ridge Plains that characterize this region.
This region exhibits multiple rates of change, from the geologic to short-term anthropologically and climatically-induced.
This region exhibits multiple rates of change, from the geologic to short-term anthropologically and climatically-induced.
The panne wetlands are endemic to the glacially-modified Great Lakes coastal region, and host threatened and endangered flora and fauna.
The panne wetlands are endemic to the glacially-modified Great Lakes coastal region, and host threatened and endangered flora and fauna.
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While water level fluctuations are part of the natural processes in this complex coastal ecosystem, Lake Michigan’s current near record-high lake levels have further worsened erosion rate, and consequently threaten public access, critical infrastructure, and important ecological areas.

The intervention site was located offshore from Hosah Park, where valuable panne habitat was quickly eroding as documented by on-going monitoring efforts.

While water level fluctuations are part of the natural processes in this complex coastal ecosystem, Lake Michigan’s current near record-high lake levels have further worsened erosion rate, and consequently threaten public access, critical infrastructure, and important ecological areas.

The intervention site was located offshore from Hosah Park, where valuable panne habitat was quickly eroding as documented by on-going monitoring efforts.

Purpose

To protect this rare and critical habitat and recreational and economic opportunities along the coast, we set out to design with naturally occurring systems to provide aquatic habitats while slowing erosion without stopping longshore sediment transport (moving parallel to the coastline). This project represents the possibilities of a middle-ground between expensive, intensive capital projects, like armoring and breakwaters, and softer, less expensive, but more maintenance-intensive projects, like annual beach nourishment. It has the potential to work in concert with those methods or alone, which expands the range of possible approaches.
no intervention
traditional intervention

Slow, but not stop, longshore sediment transport in strategic areas

The intervention is a cost-effective way to protect identified nearby critical upland habitats by dissipating high energy waves in targeted areas without disrupting low energy waves that transport sediment behind the feature.

Healthy Port Futures Intervention

Slow, but not stop, longshore sediment transport in strategic areas

Concept

The objective of this pilot project is to reduce the wave energy in the nearshore environment without disturbing longshore sediment movement. The underwater ridges of the design are more adaptive to the natural systems and less noticeable to the public eye than vertical breakwaters.
The ridge field condition is less reliant on the exact calibration on one particular feature, like an emergent breakwater to stop wave energy, and instead gradually allows the wave energy to be dissipated over an extended distance. The ridges are more cost effective, less intrusive, and allow for the nearshore to remain active during daily events while mitigating storm damage.

Design

We were enlisted to develop an innovative, lower-cost, more rapid-response intervention to slow the immediate threat to important ecological areas from the rampant erosion caused by high lake levels. Erosion in the northern portion of the park and sediment deposit in the south built up the unique curvilinear ridge-and-swale topography which supports the upland black oak savannas and the lowland wetlands. However, we know recent shifts in weather patterns and various human influences have rapidly increased the erosional process of this region, erasing what took thousands of years to develop in less than half a century.

Our design was based on a strategy to temporarily capture the benefits of moving sediments while simultaneously reducing erosive wave forces with inconspicuous underwater ridges or submerged habitat reefs.

The submerged ridge reef will create a zone of reduced wave energy without obstructing views of the open water.

The submerged ridge reef will create a zone of reduced wave energy without obstructing views of the open water.

Our design was based on a strategy to temporarily capture the benefits of moving sediments while simultaneously reducing erosive wave forces with inconspicuous underwater ridges or submerged habitat reefs.

The intervention at Illinois Beach State Park consists of a submerged ridge reef, designed to slow sediment moment and protect the valuable terrestrial panne habitat from the erosive forces of waves

The intervention at Illinois Beach State Park consists of a submerged ridge reef, designed to slow sediment moment and protect the valuable terrestrial panne habitat from the erosive forces of waves

Process

We combined physical and computational modeling to test concepts through a process that was nonlinear and iterative, yet rapid. While modern advances in computational modeling open up new possibilities in design, we still find value in working with actual water and sediment to test concepts and simulate conditions on a small scale. We tested different submerged ridge variations against physical simulations of daily, storm, and post-storm conditions. Then, computational modeling helped calibrate the size, scale, and positioning of the design before installation.
We partnered with AnchorQEA, a coastal engineering firm, to develop computational wave modeling and longshore sediment transport approximation (CERC) of the design. The computational modeling went through a series of iterations to tune it to both the site conditions and to meet the outlined goals.
Computational modeling helped calibrate the size, scale, and positioning of the design. AnchorQEA, a coastal engineering firm, worked with HPF to develop a computation wave modeling and longshore sediment transport approximation (CERC) of the design. Below is a draft run that tests the wave heights and orbital velocities with the intervention under typical daily and storm conditions from the northeast direction. Wave Heightsn for daily and storm conditions.
Computational modeling helped calibrate the size, scale, and positioning of the design. AnchorQEA, a coastal engineering firm, worked with HPF to develop a computation wave modeling and longshore sediment transport approximation (CERC) of the design. Below is a draft run that tests the wave heights and orbital velocities with the intervention under typical daily and storm conditions from the northeast direction. Wave Heightsn for daily and storm conditions.
Computational modeling helped calibrate the size, scale, and positioning of the design. AnchorQEA, a coastal engineering firm, worked with HPF to develop a computation wave modeling and longshore sediment transport approximation (CERC) of the design. Below is a draft run that tests the wave heights and orbital velocities with the intervention under typical daily and storm conditions from the northeast direction. Orbital Velocities under daily and storm conditions.
Computational modeling helped calibrate the size, scale, and positioning of the design. AnchorQEA, a coastal engineering firm, worked with HPF to develop a computation wave modeling and longshore sediment transport approximation (CERC) of the design. Below is a draft run that tests the wave heights and orbital velocities with the intervention under typical daily and storm conditions from the northeast direction. Orbital Velocities under daily and storm conditions.
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In concept development, water table experiments were conducted to explore an intervention that would allow for daily beach-building waves while reducing detrimental storm waves. Each iteration went through a series of specific wave conditions meant to glean insight into its response to daily and storm conditions. One of the iterations, a wide, uniform field condition, had promising results in dissipated both storm and daily conditions. Control Run.
In concept development, water table experiments were conducted to explore an intervention that would allow for daily beach-building waves while reducing detrimental storm waves. Each iteration went through a series of specific wave conditions meant to glean insight into its response to daily and storm conditions. One of the iterations, a wide, uniform field condition, had promising results in dissipated both storm and daily conditions. Control Run.
Overall Caption: In concept development, water table experiments were conducted to explore an intervention that would allow for daily beach-building waves while reducing detrimental storm waves. Each iteration went through a series of specific wave conditions meant to glean insight into its response to daily and storm conditions. One of the iterations, a wide, uniform field condition, had promising results in dissipated both storm and daily conditions. Wide Field Condition Run
Overall Caption: In concept development, water table experiments were conducted to explore an intervention that would allow for daily beach-building waves while reducing detrimental storm waves. Each iteration went through a series of specific wave conditions meant to glean insight into its response to daily and storm conditions. One of the iterations, a wide, uniform field condition, had promising results in dissipated both storm and daily conditions. Wide Field Condition Run
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Monitoring

The site will be monitored before and after implementation to test the effectiveness of this lower-cost, lower impact, and more rapid response intervention. The project will provide valuable insight into low-impact interventions, and accordingly, may offer a model for similar coastal areas struggling with eroding shorelines in the region. Michigan State University’s Theuerkauf Lab and ISGS will monitor onshore and offshore areas via high-resolution aerial photography, single-beam survey, and multiple-beam survey to determine the size, shape, location, and elevation of the land, vegetation, and shoreline position for an additional five years after placement. Stantec will place wave buoys to measure the wave conditions windward and leeward of the structure.

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Sean Burkholder
seanburk@design.upenn.edu
Brian Davis
mudlands@virgina.edu
Tess Ruswick
truswick@design.upenn.edu

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