TEMPORAL CHANGES IN LINEAR DUNES LOCATED IN THE SIMPSON DESERT, CENTRAL AUSTRALIA

Linear dunes are characterized by their straight to irregularly sinuous, elongated shape. Typically, the width of a linear dune is only a few tens of meters or less, but the length of an individual dune can exceed tens or even hundreds of kilometers. Linear dunes cover more desert areas on Earth than any other type of dune. They are also the only dune form that has been found on all the terrestrial worlds with an appreciable atmosphere, including Titan, Mars and potentially Venus. Despite their common occurrence, it is still not clear how they form. Previously, we made temporal observations of a single linear dune located in the Simpson Desert of central Australia [Craddock et al., 2015]. Our observations were collected on three separate occasions over an eight-year period from 2006 to 2014 and included measurements of the heights of rebar stakes placed in a gridded pattern, GPS surveys, and photographs. We observed dramatic fluctuations (accumulation and removal) of sand at the dune crests that commonly exceeded a meter per year, compared to fluctuations of only 2-3 cm on the dune flanks and in the interdune corridors. Our results suggested that the linear dunes are actively maintained by vertical accretion, which is contrary to some suggestions that they are inactive or stabilized. These observations were crude, however, and were limited by the quantity and quality of the topographic data derived from the GPS surveys. With the continuing development of UAS (unmanned aerial systems), or drones, and the topographic data that can be derived from photogrammetry techniques using drone imagery, we have begun a new monitoring campaign that includes several dunes in different locations within the Simpson Desert. Our first drone survey took place in April of 2017. New surveys are planned for October 2018. We will present the preliminary observations from these surveys and refine our original interpretations of temporal changes that have taken place. Whereas barchan and other transverse dune forms reflect transportation of sediment, our preliminary observations suggest that linear dunes primarily represent nature’s way of storing sediment.