Evolution of longshore beach contour lines determined by E.O.F. method

Abstract

SUMMARY: Detailed topo-bathymetric levellings were performed biannually for four years at Victoria Beach (Cadiz, Spain) after a beach renourishment carried out in Spring 1991. The subsequent time series were analysed using the Empirical Orthogonal Functions (EOF) method. The evolution of some characteristic longshore contour lines, such as the Highest High Water Level and the Lowest Low Water Level, is studied. The mean coastal line is related to the first spatial EOF mode. Furthermore, an objective criterion for distinguishing between a generalised recession and cyclic accretion-erosion processes due to seasonal sea-swell changes is described, and a uniformly clockwise turn of the shoreline to minimise longshore transport is identified.

Coastline sand waves on a low-energy beach at “El Puntal” spit, Spain

“…This method, also known as the empirical orthogonal function (EOF) method has been widely applied in coastal morphology, mostly focused on cross-shore variability (Winant et al, 1975;Dick and Dalrymple, 1984;Medina et al, 1994), and more recently on longshore variability (Wijnberg and Terwindt, 1995;Muñoz-Pérez et al, 2001;Miller and Dean, 2007). The purpose of the method is to describe coastline changes by using the least number of functions, called eigenfunctions.…”

Long-term evolution of a transgressive migrating dune using reconstruction of the EOF method

“…Losada et al (1991) and Medina et al (1993) also applied this technique to study cross-beach sediment transport, and Larson et al (1999) researched the responses of three beach nourishments on different temporal and spatial scales. Moreover, Muñoz-Perez and Medina (2000) and Muñoz-Perez et al (2001) studied the behaviour of profile changes during a fortnightly tidal cycle and the evolution of longshore beach contour lines, respectively.…”

Decoupling processes and scales of shoreline morphodynamics

“…EOF has been used in a variety of applications in coastal systems. Most have applied the technique to evaluate dominant modes of variability in the crossshore direction (Houser et al, 2008;Wijnberg and Terwindt, 1995;Winant et al, 1975;Yates et al, 2011) while some researchers have used EOF to assess trends and patterns in alongshore variability in shoreline position (Dick and Dalrymple, 1984;Munoz-Perez et al, 2001;Miller and Dean, 2007). In this study, EOF analysis is used to separate the spatial and temporal patterns of the mean-removed shoreline position data.…”