Digital Photogrammetric Change Analysis as

Applied to Active Coastal Dunes in Michigan

 

Daniel G. Brown and Alan F. Arbogast

 

            A pilot study was conducted to investigate the applicability of digital photogrammetric methods to the study and management of dynamic dune systems.  Two sets of panchromatic stereographic aerial photographs taken over Ludington State Park, Michigan, one pair each from 1965 (1:20,000-scale) and 1987 (1:15,000-scale), were obtained from historical archives.  Stereo models were constructed for the stereo-pairs, using post-processed differential GPS ground control points, and digital elevation models (DEMs) were extracted from each at a resolution of 3 metres.  The analysis involved computing differences between the two DEMs at each location, and computing a volume of sediment (sand) flux over the 22-year time period.  Maps of elevation change were then constructed and interpreted to suggest patterns resulting from eolian processes.  Processes of dune development, movement, and “blowout” were identifiable and measurable.  The project illustrates how recent developments in photogrammetry have enhanced capabilities for monitoring geomorphologically sensitive landscapes such as dune fields.