FORESHORE EVOLUTION OF A MIXED SAND AND GRAVEL BEACH: THE CASE OF PLAYA GRANADA (SOUTHERN SPAIN)

摘要

Mixed sand and gravel beaches (MSGBs) present a wide range of sediment sizes, with different levels of gradation and mixing at depth and frequent cross- and alongshore variations. This work addresses the evolution of the foreshore of the beach of Playa Granada (southern Spain), including its response to two significant storms and its behavior after artificial nourishment. To this end, periodic field surveys were carried out over a one-year time interval, mainly consisting of high-resolution topographical measurements and sediment sampling on the beach. We characterized the foreshore's evolution by means of correlation with the maritime climate and the analysis of different wave setup and sediment mobility formulations. The results indicate that the formation of these bars is mainly related to the maximum water elevation attained under low- to medium-energy waves. Furthermore, they further suggest that the evolution of MSGBs occurs in lower spatial and temporal scales compared to sandy beaches.