Grain-size-selective aeolian sand transport on a nourished beach

The grain-size-selective aeolian processes that take place after a beach no urishment were studied on the island of Ameland in the Netherlands. The bea ch and foredunes were sampled both before and after nourishment. Grain-size distributions of surface and subsurface sand, wind-laid sand and sand in t ransport were analysed. The unreworked fill is only moderately sorted and e xhibits a large spatial variation. Marine reworking results in a decrease o f shell fragments and a decrease in fines on the foreshore, with the except ion of the swash mark. During aeolian sand transport, aeolian decoupling re sults in a backshore with surface lag deposits with moderately sorted sand containing a substantial amount of shell fragments and silt, and patches of sand with less shell fragments. Wind-laid nourishment sand, i.e., the nour ishment sand that is blown to the dunes, contains only small amounts of the se shell fragments and the sand is finer and better sorted than the nourish ment beach sand. However, the nourishment sand that is blown to the foredun es still deviates from the wind-laid native sand; it is more poorly sorted and more negatively skewed. Furthermore, the wind-laid nourishment sand con tains significantly more coarse material, i.e, shell fragments, than the wi nd-laid native sand, which will lead to an increase in calcium carbonate co ntent in the foredunes.