Abstract
Recent extremes in water levels throughout the Great Lakes have driven large shoreline changes. In response to excess precipitation, Lake Michigan water levels rose two meters between 2013 and 2020, from record low values in 2013 to record high values in 2020. This water level change led to widespread shoreline damage to property, beaches, and infrastructure. Measurement and analysis of shoreline changes from LiDAR surveys and aerial photography in response to fluctuating water levels show that the shoreline changes are not well described by existing models developed for ocean coasts. Motivated by this disagreement, a new Great Lakes Shoreline Model was developed and applied to several Lake Michigan beaches. This reduced complexity shoreline model is based on the concept of water level disequilibrium, where changes in the water level enhance wave-driven shoreline changes. The model was calibrated and validated using satellite-derived shoreline position time series inferred from newly available SmallSat imagery, using a custom shoreline detection algorithm that was developed for this application. Application of the Great Lakes Shoreline Model to several beaches highlights the improvement afforded by the model over existing ocean-focused models. Future work seeks to generalize the model parameters in order to enable blind model applications that can in turn be used to design more resilient shorelines, and to link long-term changes in Great Lakes wave climate with potential shoreline evolution.
Bio
Dr. Troy runs the Great Lakes Coastal Processes Laboratory at Purdue University (https://troylabpurdue.org/ ). Dr. Troy received his B.S. from the University of Illinois and his M.S. and Ph.D. from Stanford University, working in the Environmental Fluid Mechanics Laboratory. With a primarily observational approach, research projects at Purdue have focused on physical processes in the Great Lakes, including turbulence and mixing, internal waves, large scale circulation and dispersion, boundary layers, convection, shoreline erosion, and thermal stratification. Dr. Troy teaches water courses in a range of topics, including elementary fluid mechanics, environmental fluid mechanics, basic water science, limnology, and surface water transport processes. He is now co-leading the Great Lakes Special Initiative at Purdue University.