Offshore Aeolian Transport Across a Beach: Carrick Finn Strand, Ireland
Keywords:Wind speed, aeolian transport, beach, dune, sand size, sediment traps, surface moisture, Carrick Finn Strand, Ireland
This study examined cross-shore differences in wind speed and aeolian sediment transport rate in relation to beach surface conditions in the lee of a 6 m high dune during 2 days of offshore- winds at Carrick Finn Strand, Ireland. Near-surface wind speed, surface moisture, carbonate content and mean grain size increased in the offshore direction; sediment sorting became slightly poorer. The rate of sediment transport was small from the dune top out to a distance of about 20 m and then increased rapidly to about 40 m seaward of the dune. The rate decreased seaward of this location early each day due to a great increase in surface moisture content. Greater rates of transport occurred seaward of this location later in the day and arc attributed to drying of the beach surface and increased wind speeds.
Rates of offshore aeolian transport on the beach in the lee of the dune are affected by shore-parallel zones differing in wind speed, surface moisture and sediment characteristics that change in location through time. These zones include a Lee-of-Dune Zone, where no aeolian entrainment occurs because of low wind speeds: an Erosion Zone, located sufficiently far from the dune that wind is effective in entraining and removing sediments: a Transport Zone where erosional losses are replaced by inputs from upwind; and an Accretion Zone on the moist portion of the foreshore.