Three-dimensional Stability Analysis of Bluffs Along the Lake Michigan Shoreline in Eastern Wisconsin
Year: 2019
Type: dissertation
Abstract: The water level in Lake Michigan has been rising since 2013. Historically, erosion of \nthe bluffs along the shoreline has increased during times of lake level increase. Erosion \nbegins at the bluff toe and progresses upslope, potentially damaging infrastructure at the bluff \ncrest. The factors controlling stability for the three bluff types, distinguished by height and \nretreat type, were investigated using Scoops3D, a three-dimensional limit equilibrium \nstability model. The bluff types can be summarized as follows: 25 m height with parallel \nretreat, 40 m height with complex retreat, and 15 m height with complex retreat. For each \nstudy site, high-resolution (10 cm) elevation models were created from photographs collected \nby drone using Structure from Motion, and steady state groundwater models were developed \nusing MODFLOW. These were used as inputs for Scoops3D along with physical properties \nof the sediment reported in the literature. Unstable areas were verified through comparison to \nthe photographs at all sites and a repeat drone flight at one study site. Slope angle and \nrelative strength of the sediment appeared to be the most significant factors controlling \nstability, while the pore water pressure from the depth below the water table acted as a \ndestabilizing agent. Increases in the water table, even for short periods, cause previously \nstable areas to become unstable. Scoops3D was able to capture the retreat type associated \nwith each bluff type, and the relative location of unstable areas along the bluff face suggest \nthat the upslope progression of erosion reaches the crest of shorter bluffs faster than taller \nbluffs.
Author: Russell Krueger
Language: English
Topic: Coastal and Marine Dynamics
Subfield: Earth-Surface Processes
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2955016872