Scroby Sands, a major nearshore sandbank on the East Anglian coast of the U.K., is constantly changing its configuration and alignment with the surrounding sandbanks and nearby coastline. This study investigates the hydro dynamical and morphological processes occurring over this complex area and provides an insight into the future morphological development of the Scroby sandbanks region. Numerical modelling, using the TELEMAC finite element system (version 5.5), is used to investigate the relative importance of waves, tidal currents, and storm surges in modifying this sandbank system and to understand the sand transport pathways and bed-evolution under a variety of hydrodynamic conditions around the sandbanks. To enhance model's performance, calibration and validation tests were conducted; field measurements of waves and tidal currents in the study area are analysed to help understand the spatial distribution of the hydrodynamic characteristics of the area. Analyses of recent and historical charts, and recentlysurveyed swathe bathymetries, are conducted to validate the morphodynamic model and to improve understanding for the morphology evolution of the study area. The model demonstrates that waves, especially northerly waves associated with a storm surge, enhance the net sand fluxes and the bed-evolution by 'stirring' the sand, while the asymmetrical tidal currents play an important role in transporting the sand. The model identifies Caister Ness as an area of sand flux convergence and a source of sand for the nearshore sandbanks (McCave, 1978), and suggests that the sand is moving to the sandbanks along features < 10 m in water depth (Caister Shoal to Cockle Shoal to Scroby Sands to Corton Sand to South Cross Sand). The relatively stable position of the -10m ODN contour on the historical charts since 1846 indicates that the regional tidal current stream dynamically maintains Scroby in its present configuration, although the exact configuration and central position of the shallowest part of Scroby varies over the time due to waves and storms. A steady increase in the area and volume of Scroby above -5 m ODN, where the major sand transport occurs, suggest a linear morphological trend rather than the recurrent cycles which were proposed by Robinson (1966) and Reeve et al. (2001a; 2001b).
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:437656 |
| Date | January 2007 |
| Creators | Park, Hyo-Bong |
| Publisher | University of East Anglia |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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