EAR-PF: Morphodynamics of giant dunes in wind and water

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Dr. Julia Cisneros has been granted an NSF EAR Postdoctoral Fellowship to conduct research on giant sand dunes formed by wind or water at Rice University, Houston, TX and Texas A&M University, College Station, TX with Dr. Jeff Nittrouer and Dr. Ryan Ewing, respectively. This project seeks to understand how giant sand dunes move and transport sediment in deserts and rivers. In deserts, giant dunes migrate and change over thousands of years, recording the variability in global climate. In rivers, giant dunes migrate over days to months and respond to significant landscape-altering events, such as extreme floods. Giant dunes exist also on other worlds (e.g., on Titan, a moon of Saturn), and here on Earth, their deposits are preserved in the sedimentary rock record providing key records of inaccessible and ancient environments. Still, little is known about their topographic structure or how multiple scales of dunes may co-exist. This information is vital to improve our understanding of giant dunes formed in various environments. This project seeks to use the expertise gained by Dr. Cisneros during her PhD investigation of dunes in rivers, allowing her to compare and contrast dune operations across both rivers and desert environments. As a native Texan, she plans to use her postdoctoral researcher platform in Houston, TX to encourage underrepresented and minoritized students to envision themselves in similar careers. The outreach work builds on Cisneros’ existing outreach efforts that seek to understand the barriers and perceptions young girls of color feel towards careers in the Geosciences. To understand this, she will run a two-day summer Geoscience Camp in order to continue learning how to engage young girls of color in support of gaining further diversity in the Geosciences.This study’s primary objective is to develop a unifying framework for bedform morphodynamics that spans environments and scales through studying the morphodynamics of Earth’s largest and most complex bedforms in deserts and rivers. Giant dunes commonly comprise smaller, superimposed dunes climbing up the large dunes stoss. Still, little is known of their topographic structure and translation, how sediment is transported across their structure, and how multiple scales of bedforms can coexist. To improve our understanding of giant dune morphodynamics, Dr. Cisneros will analyze dune morphology and identify the morphodynamics of giant, compound and simple dunes through deploying repeat surveys of river and desert dune areas. These surveys will be conducted on the lowermost Mississippi River, LA, where simple and giant, compound dunes exist, and in the Algodones Dune Field, CA, which comprises giant, compound dunes. Existing data of the White Sands Dune Field, NM will be used for investigation of simple desert dunes. Results of this study provide both research fields with new characterization bedform analysis techniques and methods for quantifying sediment flux, thereby creating an investigative framework of dune morphodynamics. Further, through relating the influence of superimposed dunes to compound dune dynamics in rivers and extrapolating those methods to deserts, this study will unlock the slow-moving morphodynamics of giant dunes on Earth and other planets. The results of this work will contribute to disciplines ranging from planetary sciences, geomorphology, sedimentology, and engineering. This project received co-funding from the Geomorphology and Land-use Dynamics program in the Earth Science division.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.