Remote Sensing Approach for Dune Migration Measurement

Recent studies in White Sands National Park have shown groundwater salinity as a contributing mechanism controlling transitions from barchan dunes to parabolic dunes. Although it is known that plant population density influences the transition from barchan to parabolic dunes, there is still lack of understanding on the role hydrogeology plays in this system. In this study we assess the ability of high-resolution spatiotemporal mapping to evaluate dune variation and compare the response to precipitation to guide in situ work for locating IFLs. High-resolution LIDAR acquired from the National Park Service was analyzed together over several years to create difference maps that show trends in dune movement. Difference maps from successive years (i.e., 2007-2008, 2008-2009, etc.) were used to measure 45 points within 3 different dune formation zones that we identified and adapted from Langfords (2009) study (i.e., barchanoid, transitional, and parabolic). Manual measurements of the leading edge of the slip face over different years were made in ArcGIS. The rates of migration were then compared temporally to determine trends in movement and compared to the average annual precipitation. Locations within the park were then selected for well installation and water sampling. Over the span of 2007 - 2010 the LIDAR surveys show the average rates of dune movement consistently descending across the active barchanoid dunes toward the more stabilized parabolic dunes. The rate of movement (m/yr) for 08-09 show an average of 43.6% increase in movement from 07-08 and 25.5% decrease when comparing 2009-2010 to 2007-2008. Dune movement in the parabolic region shows higher feedback (up to 70.48% increase) in response to the system in comparison to both the barchanoid and transitional zones. Compared to 2007 annual precipitation estimated for the region as calculated via PRISM data, White Sands shows a 53.9% increase from 2007-2008 and then 2.4% increase in 2008-2009. Trends in dune movement can be accurately assessed via this method, however additional data, including ground-based measurements, are needed to understand the effect of precipitation. Future analyses would benefit from a better system of weather stations and more frequent LIDAR collection within White Sands National Park.