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Title: Airflow and sediment transport dynamics in an arid coastal dunefield
Author: Smith, Alexander Begg
ISNI:       0000 0004 7653 0729
Awarding Body: Ulster University
Current Institution: Ulster University
Date of Award: 2017
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Aeolian dynamics, responsible for dune form and dunefield evolution, are controlled by multiple scale airflow perturbations and resultant geomorphic processes. These include modification of airflow by the underlying dune bedforms, at the micro-scale, to airflow perturbations caused by regional surface features extending into the internal boundary layer (e.g. anthropogenic development and topography), at the meso-scale. In situ studies, in aeolian geomorphology, often focus on spatially limited experiment sites measuring airflow dynamics at the landform scale. Larger scale perturbations, of regional airflow dynamics, are often neglected or little understood. This thesis aims to integrate a variety of spatial and temporal scales to identify varying levels of airflow perturbations on the Maspalomas dunefield, Gran Canaria, Spain. The goal of this research is, therefore, to provide a comprehensive understanding of the airflow modifications occurring at Maspalomas and how these in turn effect the evolution of the dunefield. Aeolian dynamics, identified at the dune and dunefield scales, were analysed by combining both in situ measurements and computer modelling. Airflow perturbations are measured and modelled at various scales across the Maspalomas dunefield, Gran Canaria, Spain. Field validated model results then allow for the identification and analysis of airflow perturbations including velocity, directionality, turbulence intensity, and complex coherent flow structures, difficult to measure in the field. At the dune form scale, high density three-dimensional anemometers measure airflow across a variety of dune shapes. In general, airflow velocity accelerates up the stoss slope before flow detachment at the crest and highly turbulent conditions in the lee. At the dunefield scale, large scale urbanization has greatly modified regional wind patterns. Across the dunefield intensified/retarded, deflected, and turbulent flow can be attributed to the successive anthropogenic development at Maspalomas. At the island scale, approaching air flow bifurcates leading to extensive steering around the islands lateral coast. In the lee-side locations, highly turbulent conditions persist due to the influence of the upwind canyon topography. The integration these various spatial/temporal scales provide significant insights on the multiple controls of regional airflow dynamics and their resultant influence on the geomorphic evolution of Maspalomas. Our results indicate that multi-scale anthropogenic and topographically induced airflow perurbations have a direct control on the geomorphic evolution of the Maspalomas dunefield.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available