Sahara Dune Sands: Quantifying Celerity, Dust Production, and Provenance

Profile
Profile Display Name:

Thomas Baird

E-mail Address:

thomas.baird.16@ucl.ac.uk

Start Year

2016 (Cohort 3)

Research interests:
Hobbies and interests:
PhD Project
PhD Title

Sahara Dune Sands: Quantifying Celerity, Dust Production, and Provenance

Research Theme

Earth, Atmosphere and Ocean Processes

Primary Supervisor
Primary Institution

UCL

Secondary Supervisor
Secondary Institution

BBK

Abstract

Criticisms of aeolian geomorphological studies often cite temporal and/or spatial scalability issues along with poor integration of geomatic techniques. This thesis seeks to address these issues while investigating sand dune celerity, sand reactivation, dust emissivity, and geological provenance. Firstly, an automated workflow was devised using COSI-Corr and Landsat L1TP products to produce a map of sand dune movement in the Bodélé Depression, Chad. The automated workflow was found to produce highly variable outputs when applied to the Grand Erg Oriental, Algeria caused by the use of mobile features, such as dune crests, as ‘stable’ ground control points in Landsat orthorectification. Secondly, a combination of structure-from-motion (SfM) optical drone mapping, ground-penetrating radar (GPR), and soil pits were used to investigate blowout scour hollows and depositional lobes in the Gonghe Basin, China. A mass balance of the scour hollows and lobes varied between sites. Approximately 50% of eroded material was not present in the depositional lobe, either being deposited in a thin layer that could not be detected by GPR or entrained in the atmosphere as dust. Thirdly, the relationship between satellite imagery source and correlation digital image correlation (DIC) engines were assessed. ASP, MicMac, and COSI-Corr correlation engines were applied to Landsat 5, Landsat 7, PlanetScope, and SPOT-5 imagery of the Gonghe Basin. Overall, no single correlator was found to work well for all satellite imagery, but some were more successful than others. The most appropriate pairings to use when measuring dune migration is dependent on computing power, the timespan being assessed, and the resolution of the data. Finally, the provenance of Saharan dune sands was determined by bulk-petrography, heavy-mineral, and detrital zircon U-Pb geochronology analyses of 44 pre-collected samples. Overall, the samples show homogeneity in their composition across the Sahara with only minor differences being identified.

Policy Impact
Background Reading
Publications
Activities
Conferences and Workshops
  • Windy Day 2016 (October 2016).
  • Windy Day 2017 (November 2017). Talk: Towards a Dune Celerity Map of the Sahara.
  • Windy Day 2018 (November 2018). Talk: More than a Windy Day: Aeolian features of the Qinghai-Tibetean Plateau.
  • 10th International Conference for Aeolian Research (ICARX) (June 2018). Talk: Towards A Dune Celerity Map of the Sahara.
  • DTP Conference 2017 (August 2017). Poster: Shifting Sands of the Sahara.
  • DTP Conference 2018 (September 2018). Organiser: Co-Chair of the Organising Committee.
  • DTP Conference 2019 (September 2019). Talk: Towards A Dune Celerity Map of the Sahara.
  • DTP Conference 2020 (September 2020).
DTP Activities
DTP Activities

Member of the Joint DTP Summer Conference Organising Committee 2018

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