Faculty Mentor(s)

Suzanne DeVries-Zimmerman, Geological & Environmental Sciences; Dr. Edward Hansen, Geological & Environmental Sciences; Dr. Brian Yurk, Mathematics

Document Type


Event Date



Interdunal wetlands/slacks develop in the Great Lakes coastal dunes when the wind scours the sand to the water table within a dune. Our previous review of historic aerial photograph/satellite imagery of Saugatuck Harbor Natural Area on Lake Michigan’s eastern shore shows slacks expand in times of higher water levels and contract, sometimes disappearing, with lower water levels, suggesting a link between the slacks’ water tables and those of Lake Michigan-Huron (MH). We extended these studies to Warren Dunes and Ludington State Parks, Leelanau Peninsula, Crystal Lake and Point Betsie using images from 1952–2018. Using QGIS, we drew polygons around three types of slack features, wet sand, standing water and slack vegetation on georeferenced photos, calculating perimeters and areas for each feature on each photo. Wetland perimeters and areas were summed annually for each feature. These values were then totaled on an annual basis (wetland extent) and compared to the Lake Michigan water level curve. Overall the wetland extent in Warren Dunes, Leelanau and Crystal Lake reflects the lake level curve, increasing as water levels rise and decreasing as they fall. Wetland extents at Point Betsie and Ludington follow the lake level curve with the exception of 1965 and 1993 at Point Betsie, and 1993–2012 at Ludington. Possible explanations for these variances include photo quality and/or a rain event(s). Overall this method provides a reliable way to evaluate historic ecohydrological changes in response to fluctuating lake levels. 3-band (red, green, near-infrared) drone imagery has also been used as lake levels rise (2017, 2018, and 2019) to examine the ecohydrological changes occurring in the large slack (>1 ha in size) at SHNA where ridges and pools create a diverse vegetation mosaic. Vegetation quadrat sampling (32 quadrats) was used to ground-truth the image interpretations.


This research was supported by the Department of Geological and Environmental Sciences.