One of the most applied models for the characterization of sandy beaches is the Wright and Short (Morphodynamic variability of surf zones and beaches: A synthesis) Beach State Model (BSM) that empirically relates dissipative, intermediate and reflective beach types to wave conditions and sediment characteristics. Here we utilize the Delft3D-4 modelling system and create an idealized morphodynamics model to explain beach morphological changes under varying wave conditions. The model accounts for the 3D hydrodynamics and sediment transport processes and is capable of simulating both erosive upstate and accretive downstate sequences. Under an energetic condition, the profile develops into an alongshore-uniform dissipative two-bar profile. Under low wave-energy condition, the morphology develops downstate, leading to initiation and evolution of rip currents following onshore movement of the bar. The bar-formation process starts with sediment erosion at the point with maximum suspended load transport by undertow and sediment deposition on the offshore side of the breakpoint. Later, the sandbar develops as a result of sediment transport convergence of wave asymmetry and the undertow and moves offshore.

The aragonitic skeletons of massive corals (Scleractinia) are commonly used as biological and paleoenvironmental archives based on their annual density banding. In case of high-resolution proxy studies, however, taxon-specific biases related to the skeletal architecture of the selected coral species can occur, which may impact the resulting skeletal growth chronologies. This study focusses on the quantification of high-resolution skeletal density records in the massive starlet coral Siderastrea siderea from a nearshore reef environment at the southern coast of Belize (western Caribbean Sea) by using two-dimensional grid-scanning americium-241 (241Am) gamma densitometry. Multiple linear sample pathways were systematically selected through central corallite areas (i.e., around the columella) and the corresponding walls (synapticulotheca) of contemporaneously formed corallites in S. siderea. By following this approach, annual density banding (or distortions in its formation) can be identified and related to the general architectural elements and/or to variations in the longitudinal alignment of corallites. The demarcation of high-density bands is often more clearly developed in the corallite walls than around the columella. Therefore, future high-resolution linear skeletal density chronologies should be established based on the more robust corallite walls to reduce such biases in density banding of S. siderea corals.