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| Titel |
Measurement of sediment settling velocities in a tidal freshwater wetland |
| VerfasserIn |
Eveline C. van der Deijl, Marcel van der Perk, Renske Visser, Eelco Verschelling, Hans Middelkoop |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250107805
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| Publikation (Nr.) |
 EGU/EGU2015-7519.pdf |
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| Zusammenfassung |
| This study aims to determine the settling characteristics of suspended sediment in
the Kleine Noordwaard tidal freshwater wetland in the south-western part of the
Netherlands. This wetland consists of a recently inundated former polder area in the
Biesbosch area, in which water and sediment have been reintroduced since 2009. The
area mainly receives sediment from the Nieuwe Merwede River, a downstream
distributary of the Rhine River. In July, September, and October 2014, water samples
were collected in 30 cm diameter PVC settling tubes near the inlet and outlet of the
area. The settling tubes were transported horizontally to a field laboratory, where
the settling velocity measurements started by placing the settling tube in upright
position within 1 hour after sampling. At logarithmic time increments, 250 ml samples
were extracted from the settling tubes through a valve at a depth of 250 mm below
the top of the tube. The sediment concentrations in the samples were determined
by filtering through 0.45 μm pore size membrane filters. First results show that
the suspended sediment concentrations were low and varied between 10 mg l-1
and 35 mg l-1. In general, the sediment concentrations decreased exponentially
during the measurements with exponents ranging between 0.98 x 10-4s-1 and
1.27 x 10-4s-1. The median settling velocities were rather consistent between the
measurement locations and measurement periods with median settling velocities of
about 0.04 mm s-1 and 75th percentiles between 0.07 mm s-1 and 0.11 mm s-1. |
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