Repeated high-precision topographic surveys of a barchan sand dune at White Sands, New Mexico using ground-based LIDAR

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2005-08

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Abstract

The purpose of this study is to document in detail the geomorphic evolution of a medium-sized barchan sand dune at White Sands, New Mexico. High precision topographic mapping of a selected dune was carried out three times over a one-year period in January 2003, May 2003, and January 2004. The pattern of sand erosion and deposition that took place between each survey was documented. Interpreted sand movement was compared with wind data obtained from the nearby Holloman Air Force Base.

A 3-D laser scanner was used to carry out each topographic survey. Using this device, 238,687, 198,194 and 1,786,496 raw elevation measurements were obtained using 2 to 10-cm spacing. The survey data sets were registered first into a common geometric coordinate, using stakes that were placed along the perimeter as ground control points. Next, the data were transformed into a Universal Transverse Mercator (UTM) geographic coordinate system. Finally, the Minimum Curvature with tension method was used to interpolate the data and generate a 2-cm-spacing digital elevation grid for each survey. The software packages GoCAD and ER Mapper were used for the data visualization and processing.

In mapping the pattern of erosion and deposition multi-band image processing techniques were applied in which the elevation changes at each grid cell were calculated. Areas of the dune that experienced positive (deposition) and negative (erosion) elevation changes between the surveys were highlighted and mapped. In addition, volume of mobilized sand was estimated. The dune maintained a similar shape and increased in size by approximately 150-m3. The dune recycled 5% and 18% percent of its total volume from January 2003 to May 2003 and May 2003 to January 2004, respectively.

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