Using Argus video monitoring to determine limiting factors of aeolian sand transport on a narrow beach

Aeolian sediment transport on beaches is responsible for dune growth and/or recovery. Models predicting potential aeolian sediment transport rates often overpredict the amount of deposition on the foredune when applied to narrow (<100 m) beaches, pointing to supply limitations. Our goal is to better understand these limitations, especially in the long-term (>years) in order to improve predicted transport volumes and the timing of transport. Here, we used 8 years of Argus video images at Egmond aan Zee, The Netherlands, in combination with routine weather data to delineate 241 limited from 467 unlimited sand transport events to explore supply-limiting factors. Our research shows that the wind is more oriented to the west (shore normal) and is generally stronger for limited transport events. This indicates that the available fetch distance is often less than the critical fetch needed for unlimited transport. This is further confirmed by the timing of the transport events, as limited events often became unlimited during low tide when the beach was the widest and fetch potentially the longest. Our results help understanding the nature of aeolian sediment transport on narrow beaches, which will hopefully lead to better predictions of annual aeolian sediment transport rates.