On the dynamics of mangueira bay-patos lagoon (Brazil)

Abstract

Mangueira Bay is a semi-enclosed system that is very important to the communities living around the city of Rio Grande. It is influenced by multiple and conflicting human impacts. This embayment is connected to Patos Lagoon Estuary through a narrow inlet and its dynamics seem to be related to the dynamics of the estuarine area. This study aims to investigate the mechanisms that control the dynamics of Mangueira Bay under the predominant forcing conditions and evaluate the influence of baroclinic estuarine circulation on the dynamics of the area. The TELEMAC-2D model was used to carry out two- and three-dimensional simulations of Patos Lagoon Estuary. The modeling results indicate that the dynamics of Mangueira Bay are directly related to the dynamics of the main access channel, which are controlled by a combination of remote and local wind effects. A time lag occurs between the excursion of salt in Mangueira Bay and the excursion of salt in the main channel, with salinity penetrating in the embayment when winds from the SW become weaker. Marked horizontal stratification is present throughout the embayment, with salinity gradients changing direction as a function of ebb and flood currents. The area where the embayment connects to the main channel presents higher salinity variability and vertical stratification, while the inner limits are less affected by the dynamics of the channel.