Aeolian Sediment Flux Derived from a Natural Sand Trap

Van der Weerd, A.J. and Wijnberg, K.M., 2016. Aeolian sediment flux derived from a natural sand trap. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 338–342. Coconut Creek (Florida), ISSN 0749-0208.In 2011, a mega-nourishment (the ‘Sand Motor’) was constructed along the Dutch Coast. Since it is a pilot project, its evolution is closely monitored. This paper presents first results on the temporal variation in aeolian sediment transport across the nourishment, based on (a) the rate of infill over a 4 year period of a small lake in the nourishment, (b) one year of semi-hourly collected video imagery and (c) four year of hourly-averaged wind data. It appeared that, apart from approximately the first half year, the infill occurred quite linearly over time at an average rate of about 1.9·104 m3/yr. The rate of infill in the first half year period was equivalent to an annual rate of 8.4·104 m3/yr. From the combination of video image data and wind data, it was derived that aeolian sand transport (by saltation) was only observed at hourly averaged wind speeds of at least 7 m/s. The monthly frequency of occurrence of above 7 m/s wind speed, was reasonably well correlated with monthly frequency of occurrence of aeolian transport (r=0.79). Nevertheless, when hourly wind speed exceeded 7 m/s, transport was only observed about 23% of the time, indicating the importance of supply limiting conditions for aeolian transport from the Sand Motor.