Evaluating the SandFlow, an acoustic sediment transport sensor

Abstract

The SandFlow is an acoustic device for detecting and measuring aeolian sand transport. It is based on the FlowCapt sensor, an instrument developed to measure aeolian snow transport. This study investigates the performance of the SandFlow in relation to the Saltiphone and the Modified Wilson and Cooke sampler, two devices frequently used in aeolian sand transport. The performance of the SandFlow was tested during three wind erosion events on the Dutch barrier island Terschelling and also in laboratory tests. Results show that the SandFlow adequately registers the periods of aeolian sand transport provided sand transport is sufficiently intense. For low sand transport the SandFlow is less accurate, although the periods with sand transport may still be detected. The sand transport fluxes measured by the SandFlow were lower than those measured by the MWAC although they remained within the same order of magnitude. Laboratory measurements showed that the efficiency of the SandFlow to register sand transport is close to 100% for sand coarser than 300 µm. For finer sand, efficiency decreases rapidly although the instrument remains usable for particles coarser than 150 µm provided appropriate corrections for efficiency are made. This study shows that the SandFlow can be used for aeolian sand transport provided the erosion event is strong enough and the particles are not too fine.