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

朱莉娅西斯内罗斯博士已被授予美国国家科学基金会博士后奖学金进行研究的巨大沙丘形成的风或水在赖斯大学，休斯敦，得克萨斯州和得克萨斯州A M大学，学院站，得克萨斯州与杰夫Nittrouer博士和瑞安尤因博士，分别。该项目旨在了解巨型沙丘如何在沙漠和河流中移动和运输沉积物。在沙漠中，巨大的沙丘在数千年的时间里迁移和变化，记录了全球气候的变化。在河流中，巨大的沙丘会在几天到几个月的时间内迁移，并对重大的改变植被的事件做出反应，例如极端的洪水。巨大的沙丘也存在于其他世界（例如，在土卫六上，土星的一个卫星），在地球上，它们的沉积物保存在沉积岩记录中，提供了难以接近的古老环境的关键记录。尽管如此，人们对它们的地形结构或多尺度沙丘如何共存知之甚少。这些信息对于提高我们对各种环境中形成的巨型沙丘的理解至关重要。该项目旨在利用西斯内罗斯博士在河流沙丘博士研究期间获得的专业知识，使她能够比较和对比河流和沙漠环境中的沙丘作业。作为一个土生土长的德克萨斯人，她计划利用她在德克萨斯州休斯顿的博士后研究平台，鼓励代表性不足和少数民族的学生设想自己在类似的职业生涯。外展工作建立在西斯内罗斯现有的外展工作的基础上，这些工作旨在了解有色人种年轻女孩对地球科学职业的障碍和看法。为了理解这一点，她将举办为期两天的地球科学夏令营，继续学习如何吸引有色人种的年轻女孩，以支持地球科学的进一步多样性。这项研究的主要目标是通过研究地球上最大和最复杂的沙漠和河流底形的形态动力学，为跨越环境和尺度的底形形态动力学制定一个统一的框架。巨型沙丘通常由较小的沙丘叠加而成，这些沙丘向上攀爬。尽管如此，人们对它们的地形结构和平移、沉积物如何穿过它们的结构以及多种尺度的底形如何共存知之甚少。为了提高我们对巨型沙丘形态动力学的理解，西斯内罗斯博士将分析沙丘形态，并通过部署河流和沙漠沙丘地区的重复调查来确定巨型，复合和简单沙丘的形态动力学。这些调查将在最低的密西西比河，洛杉矶，那里存在简单和巨大的，复合沙丘，并在阿尔戈多内斯沙丘场，加利福尼亚州，其中包括巨大的，复合沙丘。白色沙丘场（NM）的现有数据将用于调查简单的沙丘。这项研究的结果提供了新的表征底形分析技术和方法来量化沉积物通量的研究领域，从而创建一个沙丘形态动力学的研究框架。此外，通过将叠加沙丘的影响与河流中的复合沙丘动力学联系起来，并将这些方法外推到沙漠中，这项研究将解开地球和其他行星上巨型沙丘缓慢移动的形态动力学。这项工作的结果将有助于从行星科学，地貌学，沉积学和工程等学科。该项目得到了地球科学部地貌学和土地利用动力学项目的共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.