The erosion on the east coast of Spain: Wear of particles, mineral composition, carbonates and Posidonia oceanica

Abstract

Erosion on sand beaches is a problem worldwide, which together with the shortage of sand justifies the great importance of understanding the processes involved in the regression of the shoreline in order to know and adopt solutions. This study analysed the influence of sediment wear on beaches regression. For this, nine morphological units on Castellón-Valencia and nine on Alicante were analysed. The results of the granulometric and mineralogical analysis and carbonate content, showed that sediments due to different mechanisms of erosion, were worn along the shoreline. This erosion was corroborated by wear obtained in the study of white and blue quartz, where the level of rolling and the particle size were observed. Given the presence of Posidonia oceanica in much of the study area, the mineralogical composition was analysed according to the presence of this seagrass, and it was observed that the closer it gets to the coast the higher the carbonate content. This is an important fact because the increase of CO2 in the atmosphere has increased the capacity of dilution of carbonates by the seawater. All this leads to the conclusion that different wear mechanisms have caused a decrease in the size of sediments, favouring both longitudinal and transverse transport with the consequent movement of the shoreline. The transverse movement increases as the particles size decrease, and when the particles exceed the depth of closure, they do not return to the shoreline, which faces the direct consequence of the backward movement of the coastline.