Experimental Observations of the Boundary Layer and Movement in Varying Topography with Unmanned Aircraft

Desert dunes offer unique geophysical interactions, and these aeolian dominant interactions occur over a significant portion of earth surfaces. We pursued whether the movement of desert dunes can be accurately measured using unmanned aerial vehicle (UAV) data and structure-from-motion as well as tracking boundary layer propagation and change in the topography during the boundary layer interaction.  This volatile landscape makes an ideal setup for tracking imagery combined with the effect of atmospheric data.

For the photogrammetry data, three data sets total were collected in 2018, 2019, and 2021 of the Little Sahara dunes in northwest Oklahoma using a DJI Phantom 4 Pro UAV and flown along a set path. A 3D model of the dunes was created using Agisoft Metashape for each year’s data set to output a digital elevation model (DEM) using these images. After acquiring the DEMs, they were analyzed and coordinated in ArcMap. Finally, using ENVI and the add-on CosiCorr, the movement of the dunes could be estimated and shown with a vector field. Viewing transects of the of the same section of the dunes shows noticeable and evident changes over time.

Atmospheric profiles were flown using an M600 with a Young anemometer onboard. The profiles progressed from an upstream location to a downstream location. Each flight was flown remotely from approximately half a mile away, and multiple aircraft were utilized to keep an eye on the flight progress and how close the M600 was to the ground during each flight. The anemometer was sampling at a rate of 10 Hz. The data is promising, despite some noticeable noise, and shows the wind acting as expected – flowing smoothly over the crest before becoming turbulent at the base of the leeward side.