Retrieving sand dune movements using sub-pixel correlation of multi-temporal optical remote sensing imagery, northwest Sinai Peninsula, Egypt

Sand dune movements pose potential hazards against various land use activities in Egypt. To avoid or to minimize the hazards associated with sand dunes, it is critical to determine their rates and patterns of migration at high accuracy and over wide spatial coverage. This is, however, a real challenge using field work and traditional remote sensing approaches. The co-registration of optically sensed images and correlation (COSI-Corr) complements traditional approaches to provide accurate measurements at wide spatial coverage. Applying the COSI-Corr technique to two SPOT 4 panchromatic images acquired above North Sinai, we measured lateral migration of 6.0 to 19.4 m/yr with an average of 7.7 m/yr, and 9.3 to 15.0 m/yr with an average of 11.9 m/yr for the whole barchans dune areas and a selected sample of barchan dunes, respectively. We also detected that the lateral movements along the crest lines of linear dunes ranged from 4.0 to 20.1 m/yr with an average of 6.8 m/yr for the whole area occupied by linear dunes. For a selected linear dune within the study area, the lateral migration of peaks and saddles along the crest lines ranged from 5.5 to 16.7 m/yr with an average of 12.4 m/yr. The lateral migration of both barchans dunes and linear dunes showed high spatial variability. Validation of these results against the previously measured migration rates indicated high degree of accuracy of the technique. In addition, the displacement field produced from the correlation indicated that the direction of sand dune movements occurred towards the east and southeast, which is well aligned with the previously determined sand dune drifting potentials.