3D airflow modelling and dune migration patterns in an arid coastal dune field

Abstract

Mobility patterns within dune fields are driven by wind action, antecedent form and local conditions, which determine their temporal and spatial morphodynamics. This mobility can have considerable impact on human activity and infrastructure, as well as forming an important element of the sedimentary system. Understanding how dune fields migrate over time should form an essential part of future management. Although particularly important in arid and semi-arid locations due to their enhanced sand transport dynamics, research on these systems has received surprisingly limited attention, with studies largely focused on temperate and tropical examples. Here, we utilise 3D airflow modelling, in-situ wind measurements and high resolution topographical measurement of surface features at an arid coastal dune field site in Gran Canaria, Spain. Using the Computational Dynamics (CFD) software OpenFOAM, air flow is simulated over a section of dunes along a northeast-southwest orientation, representing predominant local wind direction. A 3D surface was generated using a 1m resolution LiDAR survey (conducted 2006) to provide an accurate surface topography for CFD model runs. Output from the model provided information on surface airflow, allowing forcing winds to be located on top of the 3D surface. Using a 2008 LiDAR survey we compare the response of the dune field to that forcing and dune migration patterns. Modelled surface wind speed clearly corresponds to the resulting migration patterns of dune migration. Results show, for the first time at thisresolution, that migration patterns and modelled wind flow provides useful information for arid dune studies in coastal regions.