Using Volumetric Estimates of Eolian Sand to Explain the Geography of
Coastal Sand Dunes in Lower Michigan
Alan F. Arbogast, Ashton M. Shortridge, and
Michael E. Bigsby
This study assesses the geography and volume of
coastal dune sand along Lakes Huron and Michigan in Lower Michigan. Dune field
extents were obtained from digital maps of critical dune area and soil parent
material. Volumetric estimates were determined by establishing basal surface
elevations and then calculating the average height of overlying dune deposits
using digital elevation model (DEM) data within a raster GIS framework. Results
indicate that ~ 1.8km3 of coastal dune sand occurs in Lower Michigan, with ~ 95%
located along Lake Michigan due to prevailing westerlies. Most (~ 80%) of eolian
sand is contained within 10 dune fields. Six of these fields are along the
northeastern coast of Lake Michigan where they are associated with embayments
and headlands, suggesting that changing shore angles and sandy bluffs are
important geographical variables. Dune fields along the southeastern shore
generally line the coast for greater distances and contain smaller
concentrations of eolian sand that may be partially derived from debouching
streams. The volumetric difference between the northeastern and southeastern of
Lake Michigan may occur in part because 1) northern coastal surfaces continue to
rebound isostatically, resulting in progressively younger surfaces for dune
growth, and 2) erosion in the southern end of the basin has removed dune
deposits..
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