A Data-Driven Morphodynamic Classification of Microtidal Beaches Along the Greek Coast (Eastern Mediterranean)

The 174 beach profiles investigated along the Greek coast are mainly from small, fine-grained, gently sloping, and predominantly south-facing beaches. Dunes are the most common backshore setting (39%), while 30% of profiles are backed by anthropogenic features such as roads or buildings, and 29% have beachrock. For their morphodynamic classification, Multiple Factor Analysis (MFA) and Hierarchical Clustering on Principal Components (HCPC) with k-means consolidation were applied. The first two MFA dimensions summarized exposure/wave conditions and sediment–backshore character, and the clustering results were consistent with overlapping environmental gradients within the surveyed sample. Consolidated HCPC yielded three main operational types (k = 3): exposed high-energy beaches (n = 83), sheltered fine-grained beaches (n = 64), and a smaller sheltered coarse-grained, beachrock-associated group (n = 27). Mean silhouette was 0.370; fixed-plane bootstrap Jaccard values of 0.765, 0.688, and 0.563 indicated unequal stability across Types I–III. Finer partitions (k = 5 and k = 8) provided higher-resolution views that cross-cut the three-type partition. The typology summarizes differences in wave exposure, sediment texture, and coastal setting and provides a basis for targeted monitoring; it does not quantify erosion rates or predict overwash events.