Investigating bluff collapse along Lake Michigan

Four WGNHS staff standing in front of a Lake Michigan bluff. They are spread slightly apart, and the one closest to the camera is speaking and gesturing with his hands.
J. Elmo Rawling III (front) and several other WGNHS staff on the shores of Lake Michigan.

J. Elmo Rawling III, a WGNHS Quaternary geologist, is working with Dr. Lucas Zoet in UW–Madison’s Department of Geoscience to monitor bluff stability to identify what conditions are likely to lead to slope failure in the future.

“We know that the lake level rising can cause the bluff to fail if the toe of the slope is not reinforced or armored. We want to know what other factors are most important. Is it groundwater level or the shape of the slope, or the angle of internal friction? Understanding these things can help county officials set priorities for emergency response,” said Rawling.

The team of scientists at UW and WGNHS has developed and constructed an instrument that can measure the slope before, during, and after it fails. The instrument is called the B.A.D.G.E.R. – Bluff Assessment Data Generating Experiment Recorder. This project was funded by Wisconsin Sea Grant.

Rawling and Zoet installed the BADGER in Racine County.  In December 2016, the BADGER caught a landslide in action. A bluff in Racine County dropped about 500 cubic feet of bluff material onto the shoreline below.

The BADGER measurements will allow Rawling and Zoet to prepare a full assessment of the slope stability. Then they will be able to sort out which factors most influence slope stability and make recommendations on how to assess stability in similar locations. This information will help Racine County manage its slope failure problems.

In 2018, this project was expanded to include improved estimates of slope stability by coupling structure-from-motion (SFM) photogrammetry techniques with groundwater and hillslope modeling. Using drone-based photogrammetry, Rawling and Zoet have produced 10 cm resolution maps of the slopes that will be used to estimate regions that are likely to undergo failure.

For more information, visit the interactive map of Rawling’s research and the UW Sea Grant website.