Shoreline Salients and Tombolos on the Santa Catarina coast (Brazil): Description and analysis of the morphological relationships

Abstract

Shoreline salients are low triangular landforms, which project seaward as promontories. The term tombolo is applied when this landform is joined to an island or obstacle. This work presents a literature review of salients and tombolos, with a classification of singular landforms, and discusses the relationships between morphological parameters. It also analyses the planform of these features (sigmoid model and parabolic model) on the coast of the State of Santa Catarina in the south of Brazil. Interpretation of aerial photographs and topographical maps enabled the identification of 15 tombolos and 10 salients. The observed proportions and the symmetry of these landforms are directly related to the geological conditions and predominant wave direction. For salience data, regressions between X/B and B/S presented an R2 of 0.79. Regressions between the obstacle depth (d) and the average length of incident waves were obtained, and the results (B∗d / (L2) ∼ S∗d / (L2)) exhibited high R2 values (0.83 and 0.80) for salients and tombolos for data in the literature. The parabolic model was found to be suitable in the analysis of the planform shape of the feature as this model incorporates geometric and dynamic (wave direction) variables.