Bezerra, M.O.M.; Freitas, P.P.;Baltazar, L.R.S.; Rollnic, M., 2013. Estuarine processes in macro-tides of Amazon estuaries: A Study of Hydrodynamics and Hydrometeorology in the Marajo Bay (Pará-Brazilyn: Conley, D.C., Masselink, G., Russell, P.E. and O'Hare, T.J. (eds.)

The work carried out a hydrodynamic and hydrologic characterization in the estuary of the Para River (Marajó Bay), near the Colares and Guaras Islands (pará, Brazil). The goal is to verify the behavior of the semi-diurnal macro-tide in large Amazon estuaries with an emphasis on hydrodynamic and hydrological characterization of the pará River estuary. The work proposed as targets; to investigate the hydrodynamics as to stream and water level, and the physicochemical variations of the water body. The studies were conducted in quadrature and consisted of measurements of streams, salinity, temperature and tidal range. The main results showed that the pará River estuary, as to the hydrological characteristics of the system, showed no significant variations in salinity throughout the water column in most profiles during the surveys. However, in Colares, there was an increase in the salinity over time, ranging from 3 to 5. On the Island of Guarás, the salinity was around 4 in the entire water column. The temperature in both, Colares and Guarás, did not vary, it was always 29°C. These results show that, even during the drought period, with low flow, the effect of river water is one of the main forces of circulation, and even more important than mixing processes generated by the tide. As to the hydrodynamic characteristics of the system, it was found that stream direction during sampling varied widely, and was usually followed by low speeds. Overall, the estuary shows circulation of a very mixed kind, being mainly controlled by river discharge and secondarily by the oscillations of the tide. It is important to continue studies in this region, because the estuarine processes in macro-tides of Amazon estuaries are complex and do not have characteristics in common with other macro-tides estuaries due to the great flows of rivers in the Amazon region.