Field Evaluation of Two Traps for High-Resolution Aeolian Transport Measurements

Abstract

Two traps were developed to provide short-duration, high-resolution measurements of vertical and horizontal variability in aeolian mass flux. One trap is oriented vertically to monitor variation in mass flux with elevation above the bed, and the other is oriented horizontally to record the variation in mass flux with distance from an upwind boundary. Both traps are partitioned into multiple compartments, each equipped with a separate electronic weighing system that provides a 1-Hz record of transport into that compartment. Data from an experiment conducted at Oceano Dunes, CA were used to compare trap performance. It was found that the average transport rates measured during nine runs spread over three days differed by only about 4%, and the grain size-distributions of the trapped samples were found to be virtually identical, indicating the traps had comparable relative efficiencies, despite their different physical configurations. Larger differences in measured transport existed at the shorter time scales of individual runs and portions of runs. However, detailed examination of the transport records revealed that these differences were attributable to small-scale spatial variability in the transport field. It was concluded that the traps performed well and have comparable efficiencies, however, small-scale variability in the transport field was identified as a significant issue for short-term measurements of aeolian transport.