Use of digital photogrammetry and LiDAR techniques to quantify time-series dune volume estimates of the Keeler Dunes Complex, Owens Valley, California

Aeolian dune morphology was characterized quantitatively in three dimensions to map and classify the Keeler Dunes complex (Keeler Dunes) in Owens Valley, California, from 1944 to 2012, providing a spatially and temporally resolved understanding of dune development and evolution during this period. The three-dimensional (3D) quantitative methods applied in this study provide an opportunity to build on previous two-dimensional (2D) work on dunefield evolution at this site (Lancaster and McCarley-Holder, 2013 [LM2013]). The 3D quantitative methods permitted the identification and quantification of two specific regions of the Keeler Dunes not previously described or considered. With the two new regions included in the time-series analysis, the Keeler Dunes are shown to be stable from a volume perspective since the mid-1990s, with a decrease between the late 1970s and mid-1990s. These results differ from the threefold increase reported during the same timeframe using 2D techniques by LM2013. While the Keeler Dunes were found to be stable from a volume perspective, they underwent significant geomorphological changes during this period. As the semi-active and vegetated dune mounds reactivated, depositional aprons of newly mobile sand advanced downwind. Over time, the depositional aprons formed linear dunes (in the northern dunefield) and crescentic dunes (in the southern dunefield) that are still present today. Fundamentally, the quantitative photogrammetric-based approach in this work provides significant new insight into the evolution and origin of the modern Keeler Dunes. In addition, this work underscores the importance of 3D quantitative techniques to fully characterize the temporal evolution of dynamic dunefields.