Sediment Transport Measurements in the Sizewell–Banks Area, East Anglia, U.K.

  1. S.-D. Nio,
  2. R. T. E. Shüttenhelm and
  3. Tj. C. E. Van Weering
  1. Barbara J. Lees

Published Online: 29 JUN 2009

DOI: 10.1002/9781444303759.ch21

Holocene Marine Sedimentation in the North Sea Basin

Holocene Marine Sedimentation in the North Sea Basin

How to Cite

Lees, B. J. (2009) Sediment Transport Measurements in the Sizewell–Banks Area, East Anglia, U.K., in Holocene Marine Sedimentation in the North Sea Basin (eds S.-D. Nio, R. T. E. Shüttenhelm and Tj. C. E. Van Weering), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303759.ch21

Author Information

  1. Institute of Oceanographic Sciences, Taunton TA1 2DW, UK

Publication History

  1. Published Online: 29 JUN 2009
  2. Published Print: 23 DEC 1981

ISBN Information

Print ISBN: 9780632008582

Online ISBN: 9781444303759

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Keywords:

  • sediment transport measurements;
  • bank overlies sandy and shelly sediments;
  • variation of fluorescent tracer concentration with depth in vibrocore;
  • suspended sediment load transport;
  • concentration profiles to the rouse equation

Summary

Sediment transport measurements have been made of the sand fraction of both bedload and suspended load in the Sizewell–Dunwich area, East Anglia, UK, as part of a programme studying the processes of sediment movement near linear sandbanks.

The bedload has been measured using a fluorescent coated sand. Grain-size analyses of pumped samples, taken at times of maximum flow, have shown distributions overlapping those of the top few centimeters of box core samples of the sea-bed. Therefore a coated sand, slightly coarser than the mean of that found on the sea-bed, was used. Three-quarters of a tonne of wetted fluorescent sand was pumped as a slurry down a pipe directly to the sea-bed. Surveys were carried out at 1, 3, 5, 6, 51, 165 and 230 days after injection, with a mean of 150 grab samples being obtained each time. The tracer cloud ranged from 450 to 1050 m long and 50 to 300 m wide. Depth of burial measurements were made using box and vibrocores. By D 231 the mean measured depth was 16·8 cm. The centroid movement shows that in the short term the tracer distribution was dependent on the tidal flow pattern, but in the longer term owed more to wave conditions. Calculated bedload sediment transport rates are relatively low. The maximum rate was 0·040 g cm−1 sec−1 before the tracer had achieved equilibrium with the background sand, slowing to 0·012 g cm−1 after equilibrium appeared to have been reached. During a period when there were high waves, caused by severe predominantly north-east gales, the rate rose to 0·015 g cm−1 sec−1 with the centroid having moved towards the crest of the banks.

The suspended load was measured for one tidal cycle during spring tides at each of five stations. Calculations show that in marked contrast to bedload rates, the suspended sand transport rate was high, with sediment concentrations of 423 mg l−1 at 1·75 m above the sea-bed and 1892 mg l−1 at 15 cm above the sea-bed at Station PS 4. An instantaneous rate of 30·819 g cm−1 sec−1 for the total water column has been measured at maximum flow during a spring ebb tide, and of 12·630 g cm−1 sec−1 during the flood tide. The calculated net suspended sediment transport rate is 5·660 g cm−1 sec−1 but the high rate at this site in the ebb (NNE) direction at this station is probably not typical.