Avaliação da capacidade de suporte operacional de área de despejo de dragagem portuária no Complexo Estuarino de São Marcos

Abstract

Dredging activities at the Port Complex in São Luís are essential for the continuity of operations and for the increase in port movements. The dredging dump area of Port Complex can be suffering from silting up and compromising the navigation safety, as the site is located within one of the ship anchoring areas within the Estuarine Complex in São Marcos. Therefore, this work aimed to determine the operational support capacity and the silting up rate due to the dredged material built-up from the Estuarine Complex Dump Area. The data for the characterization of hydrodynamics, sediment and particulate matter in suspension were obtained in two hydrographic campaigns carried out for 72 consecutive hours in spring tides in the rainy and dry periods in 2023 in the center of the Dump Area. The Hydrographic Surveys of Bathymetry of the studied area from 2017 to 2023 were released by Maranhão Port Administration Company along with the dredging monitoring reports from Itaqui Port. Dredging data from Ponta da Madeira Maritime Terminal from 2018 to 2023 were obtained from the Brazilian Institute of Environment and Renewable Natural Resources. After statistical treatment of speed data, tide, salinity, dissolved oxygen and temperature collected during the 144 hours of anchoring, from 576 water samples to determine suspended particulate matter and from 20 sediment samples, in the Marine Sciences Institute Facilities, it was possible to state that the Dumping Area has high hydrodynamics with low stratification. The anomaly of the Hydrographic Surveys of Bathymetry data with the data from the dredging reports indicated that the dumping of material occurred with an average of 44,047 m3 month-1 and the area had an erosion rate of 43,230 m3 month-1, indicating slight silting in the period analyzed. However, it is worth highlighting that the deepening dredging in Itaqui, with the removal of more than 312 thousand m3 of material within 16 days in 2022, most likely had a significant influence on the mentioned silting.