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Dry lake patterns

PGR-P-429

Key facts

Type of research degree
PhD
Application deadline
Ongoing deadline
Project start date
Thursday 1 October 2020
Country eligibility
International (open to all nationalities, including the UK)
Funding
Non-funded
Supervisors
Dr Cedric Beaume and Professor Steven Tobias
Additional supervisors
Dr. Lucas Goehring (Nottingham Trent University)
Schools
School of Mathematics
Research groups/institutes
Applied Mathematics
<h2 class="heading hide-accessible">Summary</h2>

Dry salt lakes form in arid valleys which are dominated by evaporation and where groundwater or rivers flow in, but not out. Despite the extreme conditions that often prevail above ground in such places, the water table remains near the surface, giving rise to interesting fluid dynamics. Brought there by the buried water, dissolved salts accumulate at the surface and form a rigid crust decorated by exotic patterns. Such dry lakes occur naturally around the world, such as Sua pan in Botswana, Salar de Uyuni in Bolivia and the lakes in the region of Death Valley in the USA. They are recognised as geological marvels: for example, Badwater Basin in Death Valley receives over a million visitors per year, and Salar de Uyuni inspired the landscape of planet Crait in Star Wars&rsquo; The Last Jedi. In arid locales, human activity can also lead to the formation of dry salt lakes. For example, the Los Angeles aqueduct diverts Owens River and allowed the 280 km^2 Owens Lake to dry into a salt-encrusted plain.

<h2 class="heading hide-accessible">Full description</h2>

<p>When wind blows, the crust erodes and the resulting salty dust gets transported away, contributing to potentially harmful atmospheric dust and to mineral transport to the oceans. The dust produced by Owens Lake, rich in toxic substances like arsenic, has been recognised as a major health hazard to the population and is being watched by the city of Los Angeles. In spite of their environmental impact, the fluid dynamics of dry lakes are not well understood. The formation of crust patterns, including the polygonal ridges, occurs over a timeline of weeks to months and has been described as part of detailed observations of the crust dynamics, but without considering any coupling with the subsurface convection. We will here consider the coupling between the crust and subsurface convection. For this, we will use a model of porous medium convection for the subsurface flow, driven by a vertical through-flow due to evaporation at the surface and by a crust saturated in salt. This model has been recently proposed by Lasser et al. (preprint) and only studied in two-dimensions, where it has provided excellent predictions of pattern sizes. Our three-dimensional modelling will extend these results to predict full patterns and their dynamics within realistic domains.</p>

<h2 class="heading">How to apply</h2>

<p>Formal applications for research degree study should be made online through the&nbsp;<a href="https://eps.leeds.ac.uk/chemistry-research-degrees/doc/apply">University&#39;s website</a>. Please state clearly in the research information section&nbsp;that the research degree you wish to be considered for is &lsquo;Dry lake patterns&rsquo; as well as&nbsp;<a href="https://engineering.leeds.ac.uk/staff/756/Dr_Xiaohui_Chen">D</a><a href="https://eps.leeds.ac.uk/maths/staff/4007/dr-cedric-beaume">r Cedric Beaume</a>&nbsp;as your proposed supervisor.</p> <p>If English is not your first language, you must provide evidence that you meet the University&#39;s minimum English language requirements (below).</p> <p><em>We welcome applications from all suitably-qualified candidates, but UK black and minority ethnic (BME) researchers are currently under-represented in our Postgraduate Research community, and we would therefore particularly encourage applications from UK BME candidates. All scholarships will be awarded on the basis of merit.</em></p>

<h2 class="heading heading--sm">Entry requirements</h2>

Applicants to research degree programmes should normally have at least a first class or an upper second class British Bachelors Honours degree (or equivalent) in an appropriate discipline. The criteria for entry for some research degrees may be higher, for example, several faculties, also require a Masters degree. Applicants are advised to check with the relevant School prior to making an application. Applicants who are uncertain about the requirements for a particular research degree are advised to contact the School or Graduate School prior to making an application.

<h2 class="heading heading--sm">English language requirements</h2>

The minimum English language entry requirement for research postgraduate research study is an IELTS of 6.0 overall with at least 5.5 in each component (reading, writing, listening and speaking) or equivalent. The test must be dated within two years of the start date of the course in order to be valid.

<h2 class="heading">Contact details</h2>

<p>For further information regarding applying, please contact Doctoral College Admissions<br /> e:&nbsp;<a href="mailto:maps.pgr.admissions@leeds.ac.uk">maps.pgr.admissions@leeds.ac.uk</a>&nbsp;t: +44 (0)113 343 5057</p> <p>For further information regarding the project,&nbsp;please contact Dr Cedric Beaume<br /> e: <a href="mailto:c.m.l.beaume@leeds.ac.uk">c.m.l.beaume@leeds.ac.uk</a></p>


<h3 class="heading heading--sm">Linked research areas</h3>