Thomas Baird

Earth, Atmosphere and Ocean Processes

UCL

BBK

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.

• Baird, T., Bristow, C., and Vermeesch, P. (2019) Measuring Sand Dune Migration Rates with COSI-Corr and Landsat: Opportunities and Challenges Remote Sensing DOI: https://doi.org/10.3390/rs11202423
• Davis, J., Grindrod, P., Boazman, S., Vermeesch, P., and Baird, T. (2019) Quantified Aeolian Dune Changes on Mars Derived from Repeat Context Camera Images Earth and Space Science DOI: https://doi.org/10.1029/2019ea000874
• Boazman, S., Davis, J., Grindrod, P., Balme, M., Vermeesch, P., and Baird, T. (2021) Measuring Ripple and Dune Migration in Coprates Chasma, Valles Marineris: A Source to Sink Aeolian System on Mars? Journal of Geophysical Research: Planets DOI: https://doi.org/10.1029/2020JE006608
• Pastore, G., Baird, T., Vermeesch, P., Bristow, C., Resentini, A., and Garzantia E. (2021) Provenance and recycling of Sahara Desert sand Earth-Science Reviews DOI: https://doi.org/10.1016/j.earscirev.2021.103606
• Baird, T., Bristow, C., Luo, W., Du, E., Bryant, R., Mitchell, T., and Vermeesch, P. (2021) Blowout Morphometrics and Mass Balances Frontiers in Earth Science DOI: https://doi.org/10.3389/feart.2021.669440