Supplement - DEM of Difference Geomorphic Change Detection

Using the 2013 OSMP lidar DEM and the newly created site DEMs, DEMs of difference (DODs) were calculated for each Site to show how the landscape has changed over a period of time (James et al. 2012). Because of differences in datums, datasets created here were offset from the 2013 dataset. As such, we selected five points on DODs in areas thought to be stable (e.g., bedrock outcrops), avoiding edges of rasters, as these values are not an accurate representation of the datum shift. The five points were then averaged and DODs shifted accordingly such that DODs could be interpreted as deposition (positive values), no change, or erosion (negative values). Artifacts within the Structure from Motion data made some absolute change values unreasonable. Therefore, to aid in visual interpretation of erosion and deposition, we chose to use relative change by normalizing the ranges of DOD values with the equation: “((DOD dataset – minimum value)/ (maximum value- minimum value)) - 0.5”. These values were interpreted from -0.5 (erosion) to 0 (no change) to 0.5 (deposition). DODs can be found in this repository.