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| Volume 104(1) 2004, pages: 71-86. | | Niels Vinther, Christian Christiansen, Jesper Bartholdy, Carlo Sørensen & Lars Chresten Lund-Hansen: | Sediment transport across a tidal divide in the Danish Wadden Sea | | Water and sediment transport were measured and calculated during
a two months period on three locations at a 3 km long tidal divide
in the Danish Wadden Sea. The water transport was flood dominated
in the largest channel, almost neutral in the smaller channel
and ebb dominated on the tidal flat. The tidal currents were short
and strong during flood tide and long lasting but weak during ebb
tide at all three stations. This tidal asymmetry caused the net sand
transport across the tidal divide to be flood directed on all three stations.
During a storm surge the currents were ebb-directed persistently
for 21 hours despite large variations in water level. Grain-size
distributions infer that the net sand transport converges to the
northeast, indicating a recent north-eastward (flood directed) migration
of the tidal divide. The suspended sediment transport during
a tidal cycle is generally directed towards the north but on few
special occasions the suspended sediment transport is southward
directed because of resuspension of a nearby-located ephemeral
blanket of sediment. The net temporal suspended sediment transport
may be directed opposite the actual water transport during a
tidal period. Depending on sediment availability, identical episodes
of wind conditions showed different patterns of sediment transport.
The results are the first published results from in situ measurements
of transport of water and sediment across a tidal divide and are important
in terms of understanding water and sediment transport
patterns in estuaries. | | >> download as pdf |
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