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.

风沙（风吹）沙丘占地球表面的 10%，既存在于广阔的沙漠沙海中，又是沿海地区抵御洪水的重要自然屏障。虽然影响完全生长的沙丘的形状、运动和模式的环境条件已被广泛研究，但可以说，我们对这些地貌的理解中最持久的缺陷也是最深刻的：风吹沙丘是如何形成的？将沙丘理解为主要的地质单元，包括这些景观对气候驱动因素、环境变化和社会影响的响应。沙丘的形成对于更广泛地了解风吹沙系统及其环境具有重要意义，而地外沙丘场的发现又增添了新的推动力，确保了沙丘形成问题在整个沙漠研究史上始终保持突出地位。 。尽管如此，现有的用于解释沙丘起源过程的想法仍然很大程度上是描述性的且未经证实的。沙丘形成问题的持续存在并不是因为缺乏对其重要性的认识，而是因为缺乏解决这一根本问题的手段。充分发展对沙丘形成的理解的关键障碍是，到目前为止，以超高空间和时间分辨率测量必要的变量来检测表面条件和风沙输送的小规模变化，已经成为人们关注的焦点。是不可能的。地球科学领域的最新技术进步既激发又支撑了这一提议，因为它们现在提供了满足过程测量的苛刻要求的机会。克服沙丘萌生这一长期存在的问题需要在研究设计中采用新颖的方法，我们的建议通过在实地工作和物理建模之间建立互补的联系，以及通过计算机建模扩大详细过程发现的应用的能力来解决小尺度的测量问题。具体来说，该提案将首次研究气流、表面特性、沙子输送变化和床形形状之间的关键相互关系，这些关系背后是对新生沙丘如何出现的有意义的理解。通过以极高分辨率现场监测表面特性和床形变化，可以实现控制过程和床形发展的全面测量。实地工作的一个关键新颖之处在于，它将在已知沙丘发育的三个精心选择的地点进行，每个地点代表沙丘形成的三个不同驱动因素的“典型地点”；表面粗糙度、表面湿度和砂床不稳定。现场工作将为在定制实验室水槽中进行的实验提供信息，该水槽旨在使用最先进的成像技术精确表征非常接近模型沙丘 3D 表面的流动。我们的现场和实验室数据集将用于驱动计算机模型，然后运行该模型来测试沙丘萌生和生长对沙漠、海岸和其他行星的一系列环境条件下的不同控制的敏感性。我们的建议建立在一种新的能力之上，能够以必要的特殊细节水平进行现场观察，并通过紧密耦合的最先进的实验室流动模拟以及基于证据的模型的开发和应用来检查沙丘的驱动因素进行增强引发。总之，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高原，以了解主要陆地地貌系统之一的起源。

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