Researching erosion along Lake Michigan

This blog post was written by UW-Madison undergraduate student Lindsay Summers, who worked at WGNHS as a social media and geology Assistant for two years before graduating in 2023. Includes March 2024 update from Elmo Rawling, Chelsea Volpano, and Mel Reusche.

A small group of mature trees on the very edge of a relatively short bluff. Roughly half of the land underneath their roots has been eroded away, leaving their roots exposed.
Trees on the edge of a bluff at Point Beach State Forest near Two Rivers, WI. “A year ago these tree roots were covered up,” said researcher Chelsea Volpano. (Photo by Lindsay Summers)

Being from Cleveland, Wisconsin, my entire childhood was spent along the coast of Lake Michigan. Not only did the beach inspire my love for geology, but all of the roads, houses, and activities in my hometown evolved around the coast and the bluffs. When I was 13 years old, an important road that my family used almost every day along the coast of Lake Michigan had to be moved away from the bluffs due to dangerous coastal erosion. This construction project took a lot of time, energy, and resources—something I’m sure other locals remember vividly. But I had the same questions at 13 that I have now:

How much will erosion affect Wisconsin communities in the future? And what’s being done about it?

In 2021, while a student at UW-Madison, I had the chance to learn more about this issue. I met with project leader J. Elmo Rawling III, a geomorphologist at WGNHS, and UW-Madison PhD candidate Chelsea Volpano during their fieldwork regarding onshore erosion and nearshore sand transport to find detailed answers to these questions. The record high lake levels in 2020 caused a major increase in shoreline erosion, which prompted thousands of dollars in damages to homes and communities. High lake levels and shoreline erosion also cause sand to be deposited in harbors along the Wisconsin coast, which becomes an expensive, labor-intensive issue when the lake level drops.

Gathering data by boat

Looking down a Lake Michigan beach on an overcast day. Away from the water's edge, the beach is lined with sandy bluffs.
The shoreline along Point Beach State Forest in Two Rivers, WI. (Photo by Lindsay Summers)

The research project on shoreline erosion had started at Point Beach State Forest near Two Rivers, mainly because, as Chelsea explained, “it is a big accumulation of sand on a natural shoreline.” For this reason, Chelsea and Elmo are studying similar processes at a second location in Port Washington since it also has a natural coastline. A considerable number of shorelines on the coast of Wisconsin have been altered by humans for various reasons, which can affect the movement of water and sediment. Since the sites in Point Beach State Forest and Port Washington are in their natural states, they are ideal for this research.

The data collection process for this project is not only done in striking locations—it’s also very interesting and fairly simple to understand, with no prior knowledge in geology required. First, a boat (either a kayak that Chelsea uses when it’s warm, or a small remote-controlled one during cold weather) containing a Single Beam Echo Sounder equipped with a highly accurate GPS unit sends out a ‘ping’ at 10 times per second. The time it takes for the ‘ping’ to hit the bottom of the lake and come back is then recorded, along with the GPS location, using software created by Chelsea and UW-Madison Instrument Technologist Neil Lord. The laptop recording the pings rides in the boat, connected to the GPS and sonar. To perform the data collection survey, Chelsea steers the boat in a grid pattern along the shore for 1 km, using evenly spaced flags to mark where to turn (see the illustration below). Then, after data collection is finished, Chelsea creates a visual of the bathymetry (a map of the depths of the lakebed) for analysis.

A diagram illustrating the path the remote-control boat takes along the shoreline to collect data. It travels away from, parallel to, and towards the beach in an S-shaped pattern, taking 90-degree turns at each direction change.
The remote-controlled boat drives in a grid pattern along the path of the arrows, turning 90° at every green flag (green triangles) to collect bathymetry data.
Looking toward Lake Michigan from a beach. The silhouette of a researcher is standing on the beach and steering a small remote-control boat on the water. The sun is low in the hazy sky, leaving a sunlit path to the horizon.
Chelsea Volpano operating the remote-controlled boat at Point Beach State Forest near Two Rivers, WI. (Photo by Lindsay Summers)
An open laptop with a data recording program faintly visible on its screen and a sandy beach visible in the background.
The laptop recording the data collected by the sonar and GPS. (Photo by Lindsay Summers)
A small orange boat about two feet long with scientific recording instruments attached to it. It sits on a beach with the edge of the lake behind it.
The remote-controlled boat: sonar is suspended underwater, the computer attaches to the front, and the GPS unit is on top. (Photo by Lindsay Summers)

As of March 2024, the team has conducted several surveys that document high lake level and low wave energy conditions. According to Chelsea, “There’s not a lot of volume moved during low lake levels, but we do see the reorganization of nearshore bars. This is pretty interesting because the bars can dampen the impact of large waves on the coast, depending on where they’re located.”  One goal is to capture data after a large storm in order to understand how the location of sand bars affects coastal erosion in multiple situations and conditions, especially since storms can cause the most damage. Unfortunately, while attempting to gather post-storm data, the connection to the boat was lost (and then found!). In the long-term future, the goal is to do similar research at other locations along the Wisconsin coast, and also create a model for bluff erosion so that more people can understand the specific effects that erosion can have on bluffs.

The future of bluff erosion

A sandy Lake Michigan beach on calm day. A dead tree lays on the beach a short distance from the camera, and just beyond the tree a person is setting up a surveying tripod. The sun is giving everything a golden tinge.
A Lake Michigan beach survey. (Photo by Chelsea Volpano)

Another important topic of discussion, especially when it comes to water levels, is climate change, so I made sure to ask Chelsea how she expects climate change to affect lake levels. She explained that it is difficult to predict lake levels very far into the future, but based on historical records it will likely continue to fluctuate. However, “With climate change, the general expectation is that these cycles will become more frequent and occur more quickly. So we might go from low to high very quickly. We see extensive erosion when lake level changes quickly, so with climate change we’ll probably be dealing with coastal erosion more consistently,” explained Chelsea via email. In other words, like many matters regarding climate change, its effects will make the pre-existing situation more drastic and harder to manage. But luckily, the more we know about coastal erosion from this research project, the more prepared we will be if erosion happens more frequently.

Currently, the bluff erosion near the road that the residents of Cleveland frequently use poses no threat to drivers. However, since this erosion continues to persist and happen more consistently, it will inevitably become a threat again in the future. Furthermore, it will likely require more expensive and time-consuming plans to adapt to it, including movement of the road itself along with the houses surrounding it. This recurring and costly problem is familiar along the Wisconsin coasts of Lake Michigan and Lake Superior. With the information being gathered from this research project, erosion events and the effects they have on shorelines will become more predictable, and hopefully less impactful.

Learn more about this ongoing research