Profile changes due to a fortnightly tidal cycle

Abstract

Measurements of profile topography, waves and tides from Victoria Beach (Spain) are used in order lo analyze the relationship between beach profile changes and neap-to-spring variation in tidal range. The principal component analysis (PCA) method is used to objectively separate the spatial and temporal modes of variability of the beach profile. It is shown ihat the most important mode of profile variability at Victoria Beach during the period of analysis corresponds to the fortnightly variation of the tidal range. The point of maximum variability is shown to be located between the neap and the spring high waler levels. The maximum difference of levelling at that particular profile point was 0.65 m. Based on previous works, a preliminary conceptual model is presented in which the fortnightly profile variations for reflective beaches are related to the RTR parameter defined by Masselink and Short (1993). It is concluded that, although these changes involve only a small amount of sand, the difference of vertical level at some particular points can be important as in the case of Victoria Beach.