MULTITEMPORAL ANALYSIS OF TOPOGRAPHIC STRUCTURE TO ASSESS DUNE FIELD RESILIENCE AT WHITE SANDS, NEW MEXICO

Recent advancements in terrain analysis paired with a growing library of repeat topographic surveys provides new opportunities to monitor surface change and to characterize topographic evolution and landscape resilience. The gypsum-sand dune field at White Sands National Park has been surveyed nine times with high-resolution aerial LiDAR since 2007. This campaign has provided important insight into dune field dynamics and presented new challenges in the reduction of complex spatiotemporal topographic information. We formalized dune field topographic structure to map and characterize dunes at White Sands from June 2007 to January 2020. We evaluated changes in dune morphometry and dynamics with precipitation, temperature, and wind conditions to better understand dune field morphodynamics and to characterize dune field resilience. Over the 13 years, average dune height, area, surface area, volume, width, length, and shape parameters did not change significantly. Migration rate and sand flux peaked in excess of 6 m yr^-1 (sand flux >17 m² yr^-1) in 2009 with slower periods averaging less than 3 m yr^-1 (sand flux <8 m² yr^-1) from 2007 to 2008 and 2010 to 2018. We also observed significant dune mass loss from 2008 to early 2009 and mass gain from early to late 2009, which we attribute to easterly winds beveling lee slopes which were rebuilt by typical southwesterly winds. The dune field therefore appears to be strongly dependent on seasonal southwesterly winds for its sediment supply. White Sands experienced six months with relatively high winds from 2010-2014, and four months between 2010 and 2012 where monthly precipitation exceeded 10 times the decadal average (>500 mm compared to <50 mm from 2005 to 2021). We posit that the reduced flux from 2010 to 2018 relates to high precipitation from 2010 to 2012. The formalization of dune topographic structure presents new opportunities and questions for quantifying dune field resilience.