Eigenfunction Analysis of Decadal Fluctuations in Sandbank Morphology at Gt Yarmouth

Abstract

Empirical orthogonal function (EOF) analysis (or Principal component analysis) has become an established technique for investigating interannual beach level fluctuations. In this paper, EOF techniques are applied to a series of historical bathymetric surveys of a nearshore sandbank system in order to investigate their long term morphological behaviour. The sandbanks cover an area approximately 30km alongshore and 10km cross-shore and lie ~2 kilometres offshore from Gt. Yarmouth which is situated on the East Coast of the UK. Geographical Information Systems (GIS) techniques were used to create digital models of the seabed from historic survey data. The models were analysed using EOF and GIS methods to identify any trends or cyclic behaviour in the morphology of the sandbanks. Evidence of changes in gross sandbank configuration, long term trends and potentially recurrent behavior have been identified, and their significance for current coastal management practice are discussed.