Quantification methods for aeolian sand transport on beaches

Abstract

Quantitative prediction of aeolian sand transport rates on beaches is still a difficult task, mainly due to the large spatio-temporal variability inherent to this type of transport. In order to validate new approaches to calculate aeolian transport, in situ field measurements are needed, combined with the knowledge on how to interpret point measurements in this spatio-temporal varying transport field. Despite the various instruments available and techniques to convert measurements to sand fluxes, there is no consensus about which trapping-device or sensor is the optimal one for aeolian sand transport studies. Often, the results of deployments with electronic sensors (optical and impact sensors) and sand traps are not similar. During the last decade, laser particle counter sensors (Wenglor fork sensors) have been used in various studies to obtain rates of aeolian sand transport in the beach-dune environment. The sensor has been tested in wind tunnels and generally seemed to record aeolian transport properly, and field applications of the sensor reported in literature seemed to provide realistic results. However, some strongly deviating results in our own transport measurements by a co-located sand trap and Wenglor sensor array urged us to further look into the detectability of various grain sizes by the Wenglor sensor.