Beach Profile Analysis by Empiric Orthogonal Functions
Keywords:Beach profile, sand bar, waves, sediment transport, field experiments, Eigenvalues, Argentine coast
A set of soundings from a beach profile surveyed during 1980 and part of 1981-1982 in the locality of Pinamar, Province of Buenos Aires, Argentina, has been statistically analysed by means of Empirical Orthogonal Functions in order to isolate their spatial and temporal variations. The first three modes of organization can explain 99.17% of the variations of the profile. It is shown that the second and third temporal autofunctions have, respectively, a significant correlation with the variation of the energy level and with the direction of wave incidence. Analyses indicate that the second mode is associated with the transport of sediment normal to the shore, while the third mode is linked to the longshore transport. The second autofunction also suggests the presence of hinge points, at depth of 0.5 m and 2 m relative to mean sea level, and through which accretional and erosional processes occur out of phase.