A descriptive sediment movement model has been created for an area of the nearshore zone near Gibraltar Point, Lincolnshire on the basis of evidence from studies of sediments, sandbank and channel morphology, bedforms, tidal currents and sediment tracer experiments. The area is subject to linear tidal currents which have created a system of tidal current ridges, tidal channels and an ebb-tidal delta. Sediment movement associated with these sandbanks and channels was found to have a net northerly drift related to an ebb tidal residual in the Boston Deep, the largest channel in the area. Sediment circulation around the sandbank system was considered to be essentially closed with a large sediment storage element represented by the sandbanks. An area of the foreshore was identified as a possible location for movement of sediment from the nearshore zone to the foreshore zone. Six Woodhead seabed drifter experiments were conducted to assess the validity of the sediment movement model. The net northerly drift of the sediment within the sandbank system was confirmed and was found to extend as far north as Ingoldmells Point. Movement of sediment from the nearshore zone to the foreshore zone was confirmed at the location suggested in the sediment movement model and was also predicted at Ingoldmells Point. The time of stranding of seabed drifters was found to coincide with periods of winds blowing offshore and from the north-east and with, periods of increasing tidal current velocity as the lunar tidal cycle approaches spring tide conditions. Movement of sediment from the nearshore zone to the foreshore zone may also occur under these environmental conditions. A study of the historical development of the sandbanks suggested an overall decrease in the size of tidal current ridges since 1871 which may be related to a decrease in the amount of sediment available for the maintenance of the sandbanks. A ness south of the Skegness Middle sandbank was interpreted as a morphological expression of foreshore adjustment to the migration of sediment from the nearshore zone to the foreshore zone at this location.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:454089 |
| Date | January 1977 |
| Creators | Dugdale, Robert Edward |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://eprints.nottingham.ac.uk/14018/ |
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