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

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.

This research will generate impact through our project partners in terms of societal, economic, industry and public education.

1) UK school students will benefit from enhanced educational materials developed in collaboration with our project partner The Royal Geographical Society (with IBG). Over 250,000 students take Geography at GCSE level (14-16 year old) in the UK and as many as 55,000 go on to take it at AS or A-Level (17-18 year old) and the number is increasing with an upward trajectory of 17-20% in the last three years. The new A-Level curriculum now includes a deserts module, indicating the relevance and importance of these environments in a changing planet and in the eyes of the general public through education policy. As this topic is new for UK Geography, there is an urgent need to provide materials to teachers.

2) National Park visitors will benefit from information displays, signage boards and fliers that we will develop with our project partners Great Sand Dunes National Park and Gobabeb Research and Training Centre, Namibia. These materials will inform visitors about desert landscapes, dune processes and climate change impact. Approximately 300,000 and 70,000 people visit Great Sand Dunes and Namib-Naukluft National Parks annually. The Namib Sand Sea, within which Gobabeb is situated, has recently been designated as a UNESCO World Heritage Site, so it is particularly important that with an anticipated increase in international visitors we disseminate our research on the very processes that enabled this landscape to develop.

3) Scientists and practitioners, both local and international will benefit from the outcomes of our findings and the potential for their broader application in land management, planetary and climate change scenarios at the dedicated impact workshop that we will hold towards the end of our grant. It will coincide with the biennial ICAR conference, the premier gathering of aeolian scientists that typically attracts ~200 international scientists, along with other interested stakeholders and industrial researchers. Items of broader interest for discussion include modelling of dune encroachment on transport routes and arable land, and dune development for coastal protection.

4) University students in Namibia and the US will benefit from the opportunity to engage with our field campaigns through project partner involvement. Particularly in Namibia there is a lack of students continuing past undergraduate level, and this exposure to an international research project should inspire them to study further. The UK investigators have positive experience of this as part of recent National Geographic funded research. Aeolian dunes are also present on other planetary bodies, and through PP Diniega, an undergraduate or MSc student will be able to develop skills and gain valuable work experience at the Jet Propulsion Lab through an inventory of early-stage bedform development on Mars.

5) Through our project partner Shell International, we will engage with the hydrocarbons industry and ensure that our scientific findings have industrial applications, particularly by improving our understanding of the ancient dune systems which contain offshore oil reserves.

6) More broadly, the general public will benefit from educational materials publicised on our webpage and twitter feed, as well as at Engineering Open House which is held at the University of Illinois and attended by >20,000 people each year. Here we will display exhibits detailing the linkage of our field, laboratory and numerical experiments, and the societal, industrial, environmental and academic application of these results in desert, coastal and planetary systems.