Hydrodynamics of Saco da Mangueira embayment: mechanisms controlling exchanges with the Patos Lagoon estuary

Abstract

The Saco da Mangueira (SM) embayment is a semi-enclosed system connected to the Patos Lagoon through a narrow inlet. This embayment represents an important system for the region, being subject to several human impacts. The objectives of this study are: 1) to investigate the main factors controlling the hydrodynamics of SM embayment; 2) to evaluate the effect of changing the morphology of the inlet where this embayment connects to the main estuary. The TELEMAC model was used to carry out numerical simulations of the Patos Lagoon estuarine area, with special interest in the hydrodynamics of the SM embayment. Modeling results indicate that the dynamics of SM embayment is directly related to the subtidal oscillations in the main access channel and to local wind effects. Salinity inside SM responds to the remote wind with a time lag of 26 h regarding salinity in the estuary. Results from the different morphological scenarios indicate that the construction of a bridge reduces the exchanges with the estuary and intensifies current velocity, resulting in significant morphological changes. Moreover, results considering a wider connection between the two systems as a management alternative for the area, did not improve exchanges.