Developing a Framework for Early Detection of Sand Dune Remobilization: A Case Study in the Parker Dunes, Arizona, USA

Desert sand dunes naturally cycle between mobility and stability; however, modern remobilization can negatively affect surrounding communities. Ongoing research on remobilization focuses on remediation strategies rather than early mobility detection. This dissertation, set in the Parker Dunes of the Sonoran Desert in western Arizona, aims to develop a better understanding of fundamental physical geography processes with the goal of early detection of desert dune remobilization.The first chapter uncovers various dune fields across Arizona that link changes in sediment supply via the integration of river systems. The second chapter uses cosmogenic burial dating to reveal that the Parker Dunes may have formed around 1.9 million years ago due to a significant flood event along the lower Colorado River that would have increased sediment supply. The third chapter uses optically stimulated luminescence dating to show that the Parker Dunes experienced periods of dune remobilization multiple times in the last approximately 48,000 years – the most recent period being about 250 years ago. A combination of increases in sediment supply and long-term drought appear to be key drivers for Parker Dune mobility. The fourth chapter explores the potential of red-orange sand grain coatings to provide insight into desert dune mobility. Aerial and satellite data roughly match high-resolution microscopy findings, suggesting that tracking changes in dune color could help detect when mobility begins to erode grain coatings. The fifth chapter investigates the relationship between drought, vegetation, and sand mobility over 30 years using climate data and remotely sensed imagery. Regression modeling reveals these relationships are complex and that simple conclusions linking vegetation change to dune mobility may be difficult to achieve, at least in the setting of the Sonoran Desert.
Several conclusions can be drawn from this dissertation. First, Parker Dune geochronology reveals that stability can occur during glacial and interglacial phases. Second, some mobility periods appear linked to substantial increases in sediment supply, while others correlate with long-term drought. Third, multiscale observations of grain coatings appear to have greater potential for early mobility detection than vegetation change. Finally, processes within the Parker Dunes are multifaceted, and no simple strategy for early remobilization detection emerged.