Seasonal sediment grain-size dynamics along a cliff-dominated beach in the eastern Mediterranean: the role of cliff erosion, waves and wind

Grain-size of beach sediments and their interactions with wave climate are crucial for modeling cross-shore and longshore sediment-transport processes and the evolution of beach morphology. Although recent studies have emphasized the temporal and spatial variability of beach sediments, these dynamics have been mostly studied in uncliffed coasts. Thus, the spatial and temporal dynamics of beach sediments along cliff-dominated coastlines remain as one of the least constrained aspects of coastal sediment dynamics. Here, we quantify the temporal dynamics of sediment along cliff-dominated beaches in the Sharon Escarpment, the Eastern Mediterranean coast of Israel, based on repeated, seasonal-scale sampling of surficial sediments along two transects, over three years. Total of 104 samples were collected and analyzed for particle size distribution. We found a general periodicity in the beach grain size: winter/spring cliff erosion associated with intense wave storms contributes eolianite clasts (very coarse sand 1-2 mm) and quartz (fine sand 180-220 μm) to the beach. During storms with significant waves >4m, beach sediments are transported northwards alongshore, and deposited all over the beach as the storm ceases. After being deposited, the surficial sediments become finer with time due to the gradual burial of the beach by wind-transported fine sand. Eolian abrasion might also contribute to the observed seasonal finning pattern of the beach sediments by disintegrating eolianite clasts. We stress that cliff erosion, waves and wind control seasonal changes in particle size distribution of sediment along cliff-dominated beaches.