Salgado Paraense's area is cut out by rivers and tide channels and the local dynamics happens according to macrotidal influence with the presence of erosion and progadation processes what generates a dynamic physiography. In this environment is located the island of Maiandeua, the object of study. Due to the socioeconomic and environmental importance of the island, it was aimed to evaluate hydrodynamic and morphodynamic parameters as well as the seasonal variations of the Caixa d’Água, Farol and Princesa beaches, in the rainy and dry period. The results showed that, in the Caixa d’Água and Farol beaches, the current possesses a preferential direction for northeast during almost the whole tide cycle with its parallel and perpendicular components the coast line showing quite similar intensities. In the Princesa beach, however, the preferential direction is northwest, besides it has the larger intensities of currents when compared with the other beaches. In the, Farol and Princesa beaches, the largest current intensities were observed during period with maximum values of 55,6, 69,2 and 111,37 cm/s, respectively. The Caixa d’Água beaches presented the largest turbidity values during the and the high water, with maximum value of 813,67 FTU for the beach during the flood tide of the dry period. In the rainy period, the maximum value of turbidez was 450 FTU, approximately, to the Caixa d’Água and Farol beaches. The bathymetry shows that until 300 m of the coast line the depth varies, approximately, 2 m, however in the next meters there is an abrupt increase of depth, it could reach 13 m. About the bathymetry variation, according to the climatic seasonality, it was showed shallower in the rainy period with difference among the periods of collection of 2 m. The analysis of the variation of the beach profile, measured during neap and spring tide, in the Caixa d’Água beach, showed sedimentary loss of 163,84 m³ among the nine days of measurement. The largest loss happened in the steepest portion of the beach, it showed the significant influence of the variation of tide kind. It is ended that the Caixa d’Água and Farol beaches are under same hydrodynamic and sedimentary processes, and bathymetry and beach profile showed that there are influences in the local morphodynamic of the climatic seasonality and variation of tide kind.
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