YES-27-D-26: From mobile dunes to the geological record: predicting desertification and sedimentary heterogeneity under environmental change

How does climate transform dune landscapes and how are those changes preserved as heterogeneous sedimentary successions in the geological record?

This interdisciplinary project welcomes applicants from geography, geology, geoscience, Earth and environmental science, geomorphology, sedimentology, geophysics, climate science, ecology, environmental data science, or a related discipline. You do not need previous expertise in both modern dune processes and sedimentary geology, or prior experience of numerical modelling. Structured training will enable you to develop across disciplinary boundaries while building on your existing strengths.

Project overview

Desert margins are among the most dynamic environments on Earth, where wind, sediment supply, vegetation, climate and human land use interact in delicate balance. Small shifts in rainfall, wind regime, grazing pressure or fire can weaken vegetation and release sand, transforming stable, vegetated dunes into fast-migrating landforms. Such activation threatens ecosystems, farmland, settlements and infrastructure, making desertification a defining land-degradation challenge of a changing climate (Mirzabaev et al., 2019).

Migrating dunes also build a geological archive. As dunes, interdunes and sand sheets accumulate, they generate cross-strata, bounding surfaces and spatially variable facies (Mountney, 2012). Yet only part of any living landscape is preserved: erosion, bedform climb, water-table position, sediment supply and subsidence dictate which deposits enter the rock record. Ancient aeolian sandstones therefore contain heterogeneity from laminae and cross-sets to dune, interdune and larger depositional elements. Because migrating dunes routinely erode earlier deposits, these strata are an incomplete, biased record of the former surface, not a simple copy of it.

This interdisciplinary PhD connects these two perspectives. It will first investigate how modern desert-margin dune systems respond to climate and land-use change, then determine how different landscape trajectories generate distinctive three-dimensional sedimentary architectures. By integrating Earth observation, sedimentology and forward modelling, the project will improve prediction of both future landscape vulnerability and the heterogeneous deposits preserved in the subsurface.

The research is built around five connected work packages, allowing candidates to enter through their strongest area and gain training in the others:

• Observe modern landscape change using satellite imagery, drone data, digital elevation models, climate records and GIS to map dune form, vegetation, disturbance and migration over time.
• Read the sedimentary record through facies analysis, sedimentary logging, palaeocurrent measurement, architectural-element analysis and interpretation of outcrop, core or ground-penetrating-radar datasets.
• Quantify multi-scale heterogeneity by describing facies proportions, body dimensions, orientation, connectivity and hierarchical relationships from facies unit to depositional-system scale.
• Link process and stratigraphy by extending a cellular-automaton model of coupled sand transport, vegetation and disturbance (Yan and Baas, 2016), then feeding its outputs into a rule-based forward stratigraphic model (Yan et al., 2024) to reconstruct dune and interdune deposits in three dimensions.
• Test future and geological scenarios by varying wind regime, climate, sediment supply, water-table position and accommodation to identify activation thresholds, preservation biases and diagnostic signatures of change.

Expected outcomes include new understanding of thresholds governing dune activation and migration at vulnerable desert margins; a process-based explanation of how dune dynamics generate stratigraphic architecture; three-dimensional models of facies distribution and heterogeneity; improved recognition of environmental-change signals and preservation bias in ancient successions; and reproducible workflows, presentations and journal publications. An applied strand, examining connectivity where aeolian sandstones act as aquifers or reservoirs for groundwater, hydrocarbons, CO2 or hydrogen storage, can be developed to suit the student’s interests.

Training and development

Training will be tailored to the student’s background and will support progressive development in:

• Aeolian geomorphology, sediment transport and dryland environmental change.
• Sedimentology, facies and architectural analysis, stratigraphic concepts and geological interpretation.
• Field data collection, sedimentary logging, palaeocurrent analysis and, where appropriate, photogrammetry or geophysical datasets.
• GIS, remote sensing, digital elevation analysis and spatial statistics.
• Cellular-automaton and forward stratigraphic modelling, including model design, calibration, sensitivity testing and uncertainty.
• Programming and reproducible research, potentially using MATLAB, Python or R.
• Scientific writing, visual communication, conference presentation and publication.

Supervision and opportunities

The supervisory team offers complementary expertise in aeolian geomorphology and sedimentology, dune and vegetation interactions, climate and environmental analysis, sedimentary architecture, and forward numerical modelling. Regular supervision will help the student integrate these perspectives and shape a coherent PhD around their developing interests.

The project has publication potential in journals including Geomorphology, Sedimentology, Aeolian Research, Earth Surface Processes and Landforms, Nature Geoscience, Computers & Geosciences, and Global and Planetary Change. It will develop transferable skills relevant to academic research, environmental consultancy, geospatial analysis, geological surveys, climate-risk assessment, geoenergy and subsurface characterisation.

Eligibility

Applicants should hold a BSc degree, or equivalent, in geography, geology, Earth or environmental sciences, geophysics, or a related discipline. Applicants from climate science, ecology, environmental data science or other relevant quantitative disciplines are also encouraged to apply.

An interest in environmental change, landscape processes or sedimentary systems is essential. Experience in one or more of GIS, remote sensing, sedimentological analysis, numerical modelling or programming would be advantageous, but is not required. Quantitative confidence and a willingness to develop computational skills are more important than prior experience with a particular software package or programming language.

 

References

• Mirzabaev, A., Wu, J., Evans, J., Garcia-Oliva, F., Hussein, I., Iqbal, M., Kimutai, J., Knowles, T., Meza, F., and Nedjraoui, D., 2019, Chapter 3: Desertification: Special Report on Climate Change and Land of Intergovernmental Panel on Climate Change (IPCC).
• Mountney, N. P., 2012, A stratigraphic model to account for complexity in aeolian dune and interdune successions: Sedimentology, v. 59, no. 3, p. 964-989.
• Yan, N., and Baas, A. C. W., 2016, Environmental controls, morphodynamic processes, and ecogeomorphic interactions of barchan to parabolic dune transformations: Geomorphology.
• Yan, N., Colombera, L., Cosgrove, G. I., and Mountney, N. P., 2024, A 3D forward stratigraphic model of aeolian dune evolution for prediction of lithofacies heterogeneity: Computers & Geosciences, v. 187, p. 105594.