Whole-island wind bifurcation and localized topographic steering: Impacts on aeolian dune dynamics

Alex Smith; Derek W T Jackson; J Andrew G Cooper; Meiring Beyers; Colin Breen

doi:10.1016/j.scitotenv.2020.144444

Whole-island wind bifurcation and localized topographic steering: Impacts on aeolian dune dynamics

Sci Total Environ. 2021 Apr 1:763:144444. doi: 10.1016/j.scitotenv.2020.144444. Epub 2020 Dec 25.

Authors

Alex Smith¹, Derek W T Jackson², J Andrew G Cooper², Meiring Beyers³, Colin Breen⁴

Affiliations

¹ School of the Environment, University of Windsor, Windsor, Ontario N9C 2J9, Canada. Electronic address: absmith9@uwindsor.ca.
² School of Geography and Environmental Science, Ulster University, Coleraine, UK; Geological Sciences, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Westville Campus, Durban, South Africa.
³ Klimaat Consulting & Innovation Inc., 49 Winston Cr, Guelph, Ontario N1E 2K1, Canada.
⁴ School of Geography and Environmental Science, Ulster University, Coleraine, UK.

PMID: 33373783
DOI: 10.1016/j.scitotenv.2020.144444

Abstract

Topographic steering has been observed around Gran Canaria, a high-profile circular island located in the Canary Island Archipelago, Spain, culminating in a complex lee-side wind regime at the Maspalomas dunefield. Maspalomas has experienced rapid environmental changes since the 1960s, coincident with a boom in the tourism industry in the region and requires further examination on the linkages between meso-scale airflow patterns and aeolian processes modifying the landscape. The aim of this work is to simulate mean and turbulent airflow conditions at Maspalomas due to incremental changes in the regional wind direction and to compare these results to the predicted and observed aeolian dynamics taken from meteorological records, a global wind retro-analysis model, and remote sensing data. A Smagorinsky Large Eddy Simulation (S-LES) model was used to identify meso-scale airflow perturbations and turbulence at different locations around the island. Variability in meteorological data was also identified, with sites recording accelerated or retarded velocities and directional distributions ranging between unimodal to bimodal. Using a global retro-analysis model, relatively consistent up-wind conditions were predicted over a period coinciding with three aerial LiDAR surveys (i.e., 2006, 2008, and 2011) at the Maspalomas dunefield. Despite the consistent predicted airflow conditions, dune migration rates dropped from 7.26 m y^-1 to 2.80 m y^-1 and 28% of dunes experienced crest reversal towards the east, or opposite of the primary westerly migration direction during the second time period. Our results indicate that meso-scale airflow steering alters local wind conditions that can modify sediment transport gradients at Maspalomas. Given the rapidity of environmental changes and anthropogenic impacts at Maspalomas, these findings improve our understanding on the aeolian dynamics at Maspalomas and can be used to inform future management strategies. Lastly, the approach used in this study could be applied to other high-profile island settings or similarly complex aeolian environments.

Keywords: Aeolian; Computational fluid dynamics (CFD); Dunes; Remote sensing.