NSFGEO-NERC: The Origin of Aeolian Dunes (TOAD)

NSFGEO-NERC：风沙丘的起源 (TOAD)

• 批准号: NE/R010196/1
• 负责人: Joanna Nield
• 金额: $ 64.96万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FR010196%2F1
• 关键词: NSFGEO; NERC; Origin; Aeolian; Dunes

Aeolian (wind-blown) sand dunes occupy 10% of the Earth's surface, both in vast desert sand seas and as important natural defences against flooding along coasts. While the environmental conditions that influence the shape, movement and patterns of fully grown dunes have been extensively studied, arguably the most enduring deficiency in our understanding of these landforms is also the most profound: how do wind-blown dunes initiate?Initiation is central to understanding dunes as major geological units, including the response of these landscapes to climatic drivers, environmental change and societal impact. The significance of dune initiation for the wider understanding of wind-blown sandy systems and their contexts, for which the discovery of extra-terrestrial dune fields has added a recent impetus, ensures that the question of initiation has remained prominent throughout the history of desert research. Despite this, existing ideas proposed to explain processes of dune origin have remained largely descriptive and uncorroborated. The persistence of the question regarding dune initiation is not due to an absence of appreciation of its importance but, rather, a lack of the means to tackle this fundamental issue. The critical obstacle to a fully developed understanding of dune initiation is that, until now, measurement of the necessary variables, at the ultra-high spatial and temporal resolutions required to detect small-scale variations in surface conditions and wind-blown sand transport, has been impossible. Recent technological advances in the geosciences both inspire and underpin this proposal, as they now provide the opportunity to meet the demanding requirements of process measurement. Surmounting the abiding problem of dune initiation requires novel approaches in research design and our proposal tackles the issues of measurement at small scales by forging complementary links between fieldwork and physical modelling, as well as an ability to widen the application of detailed process findings through computer modelling. Specifically, this proposal will for the first time examine the key inter-relationships between airflow, surface properties, changes in sand transport and bedform shape that lie behind a meaningful understanding of how nascent dunes emerge. Full measurement of controlling processes and bedform development will be achieved through field monitoring of surface properties and bedform change at extremely high resolution. A key novelty of the fieldwork is that it will be carried out at three carefully chosen locations of known dune development, with each location representing the 'type site' for three different drivers of dune initiation; surface roughness, surface moisture and sand bed instability. The fieldwork will inform experiments undertaken in a bespoke laboratory flume that is designed to enable accurate characterisation of flow very close to the 3D surface of modelled dunes using state-of-the-art imaging techniques. Our field and laboratory dataset will be used to drive a computer model that we will then run to test the sensitivity of dune initiation and growth to different controls in a range of environmental conditions in deserts, coasts and on other planets. Our proposal is built on a new capability to make field observations at the requisite exceptional levels of detail, augmented by closely coupled state-of-the-art laboratory flow simulations, plus the development and application of evidence-based modelling to examine drivers of dune initiation. In concert, this approach represents an unprecedented opportunity to overcome a truly enduring plateau for understanding the origins of one of the major terrestrial landform systems.

风风（风吹）沙丘占据了地球表面的10％，无论是在广阔的沙漠沙海还是重要的自然防御措施，以防止沿海地区的洪水泛滥。虽然已经对影响全成长沙丘的形状，运动和模式的环境条件进行了广泛的研究，但可以说，对我们对这些地形的理解最持久的缺乏也是最深刻的：最深刻的是，风吹出的沙丘如何启动？启动是将沙丘作为主要地质单位的理解，包括对这些园林对这些园林的反应，环境变化，包括对这些园林的反应，环境变化和社会。沙丘启动对对风吹沙系统及其环境的更广泛理解的意义，为此，发现外星沙丘领域的发现增加了最近的动力，可确保在整个沙漠研究史上启动问题一直很突出。尽管如此，建议解释沙丘原产过程的现有思想在很大程度上仍然是描述性的和未经修复的。关于沙丘启动问题的持续存在并不是由于缺乏对其重要性的欣赏，而是缺乏解决这一基本问题的手段。对沙丘开始完全理解的关键障碍是，到目前为止，在不可能在表面条件和风吹式沙子运输中检测小规模变化所需的超高空间和时间分辨率下测量必要变量。地球科学的最新技术进步激发了这一建议，因为它们现在提供了满足过程测量要求要求的机会。克服持久的沙丘启动问题需要研究设计中的新方法，而我们的建议可以通过在现场工作和物理建模之间建立互补的联系来解决小规模的测量问题，以及通过计算机建模扩大详细过程发现的能力。具体而言，该提案将首次研究气流，表面特性，沙子传输变化和床形状之间的关键相互关系，这是对新生沙丘如何出现的有意义的理解。通过现场监测表面特性和极高分辨率的床形变化，将对控制过程和床形开发进行全面测量。现场工作的一个主要新颖性是，它将在已知的沙丘发展的三个精心选择的位置进行，每个位置代表三个不同的沙丘驱动因素的“类型地点”；表面粗糙度，表面水分和沙床不稳定性。该野外工作将为定制的实验室水槽中进行的实验提供信息，该实验旨在使流量能够使用最新的成像技术对非常接近建模沙丘的3D表面进行精确表征。我们的现场和实验室数据集将用于驱动计算机模型，然后我们将运行该模型，以测试在沙漠，海岸和其他行星上的一系列环境条件下，沙丘启动和增长对不同控制的敏感性。我们的建议建立在新的能力之上，以在必要的特殊详细程度上进行现场观察，并通过紧密耦合的最新实验室流动模拟加强，以及开发和应用基于证据的建模来检查沙丘启动的驱动因素。在一致的情况下，这种方法代表了一个前所未有的机会，可以克服真正持久的平稳，以理解主要的地面地形系统之一的起源。

项目成果

Dune Initiation in a Bimodal Wind Regime

• DOI: 10.1029/2020jf005757
• 发表时间: 2020-11-01
• 期刊: JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
• 影响因子: 3.9
• 作者: Delorme, Pauline;Wiggs, Giles F. S.;Valdez, Andrew
• 通讯作者: Valdez, Andrew

Topographic perturbation of turbulent boundary layers by low-angle, early-stage aeolian dunes

低角度早期风成沙丘对湍流边界层的地形扰动

• DOI: 10.1002/esp.5326
• 发表时间: 2022
• 期刊: Earth Surface Processes and Landforms
• 影响因子: 3.3
• 作者: Bristow N

Local Wind Regime Induced by Giant Linear Dunes: Comparison of ERA5-Land Reanalysis with Surface Measurements

• DOI: 10.1007/s10546-022-00733-6
• 发表时间: 2022-08
• 期刊: Boundary-Layer Meteorology
• 影响因子: 4.3
• 作者: C. Gadal;P. Delorme;C. Narteau;G. Wiggs;M. Baddock;J. Nield;P. Claudin

Field Evidence for the Initiation of Isolated Aeolian Sand Patches

• DOI: 10.1029/2022gl101553
• 发表时间: 2023-01
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: P. Delorme;J. Nield;G. Wiggs;M. Baddock;N. Bristow;J. Best;K. Christensen;P. Claudin