Determination of the study period necessary for calculating the equilibrium beach profile and the depth of closure

Abstract

The morphology and hydrodynamic conditions to which a beach is exposed are important for solving many of the problems faced by coastal management (protection and/or regeneration of the coasts). Monitoring and modelling of coastal elements such as depth of closure or equilibrium beach profile has been extensively studied, although on very different time scales ranging from days to decades. However, none of these studies establishes a period of time to adequately characterize these elements, a very important data for the coastal manager. Thus, this article analyses the depth of closure, parameter A of the potential function of the equilibrium beach profile, and the maritime climate in seven profiles located to the north and south of the port of Valencia (Spain) covering a period of 20 years, with the aim of determining the optimum study period for obtaining the described elements. It is important to highlight the complexity of the study area, which includes dynamic sand bars, longitudinal and transverse transport of sediments, as well as actions to expand the Port and nourish beaches during the analysed period. The results obtained show an evident trend towards an asymptote after 5 years for the depth of closure, parameter A and wave height with probability 0.137% and its associated period. Therefore, it is concluded that for the determination of the depth of closure and the equilibrium beach profile, the data collection time must be at least five years to achieve the reliability of the results and actions on the coast. The designers of coastal actions to obtain an improvement in the coastal management can apply these findings worldwide.