Estudo das variáveis oceanográficas na área de influência do terminal marítimo de passageiros do porto de Fortaleza Praia Mansa, Ceará, Brasil

Abstract

Sedimentation of navigation channels, ditches pipelines and ports often is a key issue in the planning and design of new structures or improvements of existing ones. The sandy shores exposed to moderate or strong waves, siltation associated with sediment movement can create navigation problems, as well as generate considerable costs of dredging. The studied area is in a beach formed in the shadow of a jetty by the effect of wave refraction caused by anthropogenic alteration of the local dynamics. The main dynamic agents that promote change in the shape of the northeastern coast of Brazil are the waves, currents and winds. The Mansa Beach is located in the cove of Fortaleza, Fortaleza, Ceará, construction site of the Passenger Terminal of the Port of Fortaleza (initiated 2012) where was made the monitoring of oceanographic variables, the sedimentology and morphological patterns of beach along the construction period. The main objective of this work is to contribute to oceanographic and sediment data showing the dynamics that should be established after the morphological changes in the Port Basin. Data collection was structured on 4 ground campaigns and 10 two points oceanographic campaigns, performed from February 2012 to February 2014. Exact 100 sediment samples were collected for analysis of particle size and organic matter content and calcium carbonate and played 34 profiles beach spread on land campaigns. In oceanographic monitoring the winds, waves, tides and currents was carried out and surface water samples (130 samples) and bottom (117 samples) collected each hour for a half cycle of tide (13 hours). The method of data processing consisted basically in setting up graphics of short time series (hours and days). As for the beach profiles, some profiles were selected to constitute beach cells that were used for qualitative comparison of the variations over the year 2012. It was concluded in a general manner, that the beach cells C1 and C3 tend to exhibit dissipative characteristics on the beach, while C2 tends to have intermediate beaches characteristics, which is more exposed to the effect the diffracted waves. In sediment terms, the results found an inconsistency in the size fraction described (Terminal’s Environmental Impact Assessment) in the shoreface of Praia Mansa region found in this work to be fine sand and comparative study was presented medium sand. For organic matter content was obtained averaging 0.87% and 4:44% calcium carbonate. The winds were presented at an average speed greater than 4.5m/s. The significant wave height was 0.98m for the exposed area and 04m for sheltered area. The average amplitude of the tide came in 2.05m. The currents were more intense in its E-W component, with predominant direction for W and suspended material had an average concentration of 93mg/L in surface and 83.4 mg/L both at the dry season. In the rainy season the concentration of material in suspension was between 71 and 80mg/L. Results were in general consistent with the values described in the literature.