Hydrodynamic study of bay beaches – a case study of Itapocorói Bay, Brazil

Abstract

The hydrodynamic understanding of Bay Beaches is an essential feature in the coastal management, since it constitutes the base required to the development of future projects and studies, and has many applications in different areas (e.g. coastal erosion, water quality, ecology, etc). An investigation that could explain the hydrodynamic behaviour, the vortex formation, the circulation pattern of currents and their interaction with the tide and local wind inside the bay beaches, was held on the shores of Itapocorói’s Bay (Alegre and Piçarras), in the north-central coast of Santa Catarina – Brazil. In this context, several campaigns were carried out to measure the tide, current at different depths and study the behaviour of the local wind. These data were used as 3D model forcing to characterize the circulation patterns on the bay and verify the existence of a vortex during the data collection period. Scenarios with different characteristic winds (constant and uniform) were then simulated and the conditions in which these structures formed were determined. The model results have enabled to make a characterization of the general pattern of currents in Itapocorói Bay and revealed the vortex formation in the southern part. Those structures can have clockwise or counter-clockwise gyre depending on the direction of the incident wind. The simulations show a vortex located in the south area of the bay with a counterclockwise gyre when the winds are coming from the South and Southeast quadrant. With northeast winds, sporadic and short vortices with clockwise can be formed.