Long-term video monitoring of aeolian activity on a narrow beach

Abstract

The wind transports sand from the beach to the dunes, causing dune growth. This process takes months to years. Predicting Aeolian sand transport on these time scales is difficult, as existing models only use wind speed as a variable under ideal conditions. Aeolian transport on narrow (<100 m) sandy beaches is influenced by several factors, causing the moments of predicted sand transport not always to match with reality. The main aim of this thesis is to clarify the timing of aeolian transport on a narrow beach and the associated key factors. This is done using a video monitoring system and weather data. A strong, cross-shore wind causes limited sand transport, whereby the expected transport based on the wind speed did not result in the expected sand transport on the video images. Unlimited transport only occurs in strong winds when they are alongshore. With unlimited transport with smaller wind speeds, the wind can also be cross-shore, which mainly occurs in summer. The beach width and wind direction are built into a new sand transport model. The model predicted moments of (un)limited sand transport, whose timing was reasonably in line with expectations. According to the model, unlimited transport is rare, but they can potentially make a significant contribution to transport to the dunes. The next step is to test the model at other locations and with in-situ measurements. This improves aeolian sand transport predictions towards the dunes, where it can contribute to protecting the land against marine flooding and to a diverse ecosystem.