Advances in Measurement Techniques for Estimating Sand Dune Movements

Sand dunes move in different magnitudes and directions. The measurement of dune movements has followed two approaches: field and remote sensing techniques. Field techniques rely on establishing markers on and around dunes to measure monthly or seasonal dune displacements. Although field techniques are reliable, they provide measurements on targeted dune(s) at limited temporal intervals. The traditional remote sensing techniques involve comparing multi-temporal aerial photographs or satellite images to regularly measure dune movements over wide spatial coverage. However, the atmospheric conditions and imaging geometry of acquiring satellite images along with labor bias through tracing dune boundaries may affect the accuracy of these measurements. To overcome the shortcomings of both field and traditional remote sensing techniques, the automatic correlation of optical images represented an advanced technique to measure dune movements with sub-pixel accuracy on a field scale. Similarly, the multi-temporal InSAR coherence change detection technique has been developed to detect small changes in dune surfaces. However, none of the previous techniques were able to constrain aeolian processes associated with dune movements. With the comparison of 3D LiDAR images, it is now possible not only to determine the 2D dune movements, but also to estimate the volumetric changes associated with these movements.