MORPHOLOGICAL EVOLUTION OF THE GREAT YARMOUTH SANDBANK & CHANNEL SYSTEM

Anna-Marie Bakare, Richard Simons, Jeremy Morley, Serge Guillas

Abstract


This paper investigates the morphological history of a sandbank system from the 19th century to the present and evaluates the applicability of a new data-driven method for morphological modelling that accounts for multi-dimensional spatial relationships. Trend analyses of point locations, profile transects and contours were carried out to investigate the morphological evolution of the domain, while the spatial regression model is used for modelling. Results from the trend analysis indicate there is a constant northern migration of the sandbank features. Furthermore the physical extents of the banks are increasing in the alongshore direction. There is also a lateral shift in the bank positions, which occurs on a multi-decadal periodicity, and where changing bank configurations coincide with channel formation and disappearance at the 10m contour. Predictions with the spatial regression model show it represents the behaviour inherent in the data and system, demonstrated by the prediction RMSE being less than the mean seabed variability. In addition, the model predicts bed depth to an accuracy of ±0.25m on the top of the banks or where the gradient of the seabed is shallow. However, where there is a large change in depth over a short distance the prediction error is increased.

Keywords


sandbanks; Great Yarmouth; data-driven statistical morphological modelling

References


Bakare, A., Guillas, S., Morley, J. & Simons, R. (2009) A two-dimensional spatial statistical model for morphodynamic seabed modelling and prediction. IN Masaru, M. & Sato, S. (Eds.) Proceedings of Coastal Dynamics 2009: Impacts of human activities on dynamic coastal processes. Tokyo, Japan, 7-11 September 2009, World Scientific. Paper 107.

Cloet, R. L. (1963) Hydrographic Analysis of the Sandbanks in the Approaches to Lowestoft Harbour.Admiralty Science Publications, Number 6. London, Hydrographic Department Admiralty.

Cooper, W. S., Townend, I. H. & Balson, P. S. (2008) A synthesis of current knowledge on the genesis of the Great Yarmouth and Norfolk Bank Systems. The Crown Estate.

Dolphin, T. J., Vincent, C. E., Coughlan, C. & Rees, J. M. (2007) Variability in sandbank behaviour at decadal and annual time scales and implications for adjacent beaches. Journal of Coastal Research, SI 50, 731-737.

Dyer, K. R. & Huntley, D. A. (1999) The origin, classification and modelling of sand banks and ridges. Continental Shelf Research, 19, 1285-1330.http://dx.doi.org/10.1016/S0278-4343(99)00028-X

Horrillo-Caraballo, J. & Reeve, D. (2008) Morphodynamic behaviour of a nearshore sandbank system: The Great Yarmouth Sandbanks, UK. Marine Geology, 254, 91-106. http://dx.doi.org/10.1016/j.margeo.2008.05.014

HR Wallingford (2002) Southern North Sea Sediment Transport Study Phase 2. EX 4526.Wallingford, HR Wallingford.

Huthnance, J. M. (1973) Tidal current asymmetries over the Norfolk sandbanks. Estuarine, Coastal and Shelf Science, 1, 89-99.

Huthnance, J. M. (1991) Physical oceanography of the North Sea. Ocean and Shoreline Management,16, 199-231. http://dx.doi.org/10.1016/0951-8312(91)90005-M

Kenyon, N., H. & Cooper, B. (2005) Sandbanks, sand transport and offshore wind farms, Unpublished Report.

Pye, K. & Blott, S. J. (2006) Coastal processes and morphological change in the Dunwich-Sizewell area, Suffolk, UK. Journal of Coastal Research, 22, 453-473.http://dx.doi.org/10.2112/05-0603.1

Reeve, D., Li, B. & Thurston, N. (2001) Eigenfunction Analysis of Decadal Fluctuations in Sandbank Morphology at Gt Yarmouth. Journal of Coastal Research, 17, 371-382.

Reeve, D. E., Horrillo-Caraballo, J. M. & Magar, V. (2008) Statistical analysis and forecasts of longterm sandbank evolution at Great Yarmouth, UK. Estuarine Coastal and Shelf Science, 79, 387-399.http://dx.doi.org/10.1016/j.ecss.2008.04.016

Robinson, A. H. W. (1966) Residual currents in relation to shoreline evolution of the East Anglian coast. Marine Geology, 4, 57-84.http://dx.doi.org/10.1016/0025-3227(66)90037-5

Stride, A. H. (1988) Indications of Long-Term Episodic Suspension Transport of Sand across the Norfolk Banks, North-Sea. Marine Geology, 79, 55-64. http://dx.doi.org/10.1016/0025-3227(88)90156-9

Sutherland, J., Peet, A. H. & Soulsby, R. L. (2004) Evaluating the performance of morphological models. Coastal Engineering, 51, 917-939. http://dx.doi.org/10.1016/j.coastaleng.2004.07.015

Thurston, K., Vincent, C. & Dolphin, T. (2009) Interactions between sandbanks - The Great Yarmouth Banks, UK. IN Masaru, M. & Sato, S. (Eds.) Proceedings of Coastal Dynamics 2009: Impacts of human activities on dynamic coastal processes. Tokyo, Japan, 7-11 September 2009, World Scientific. Paper 87.

Van Rijn, L. C., Walstra, D. J. R., Grasmeijer, B., Sutherland, J., Pan, S. & Sierra, J. P. (2003) The predictability of cross-shore bed evolution of sandy beaches at the time scale of storms and seasons using process-based Profile models. Coastal Engineering, 47, 295-327.http://dx.doi.org/10.1016/S0378-3839(02)00120-5


Full Text: PDF

Creative Commons License
This work is licensed under a Creative Commons Attribution 3.0 License.