Dinâmica sedimentar do sistema estuarino-lagunar da Ilha do Guajirú - Itarema/CE

Abstract

The west coast of the State of Ceará is marked by the presence of estuarine-lagoon systems associated with sandy barriers. These environments are complex physical systems, formed on flat coasts and with high accumulation, which are subject to natural changes and of anthropic origin due to their strategic location and, consequently, the countless socioeconomic activities practiced there. The sedimentation of these systems is directly linked to the various sources of sediment, such as: beaches, sea, barriers, erosion of the basin in which the system is inserted in addition to the processes that occur within the system itself. In addition to the contribution, they also contribute to the sedimentary dynamics, the hydrological conditions, having winds, tides, waves and river flows as the main agents. The objective of this research is to map the sedimentological facies of the estuarine-lagoon system of Ilha do Guajirú in the municipality of Itarema, located 220 km from Fortaleza. First, two campaigns were carried out (drought and rainy season) for sediment collections. These were processed in the laboratory, using granulometric analysis and determination of calcium carbonate (CaCo3) and organic matter (OM) contents. For statistical analysis of these data, the Granulometric Analysis System - SAG was used. Subsequently, these data were plotted in a Geographic Information System (GIS) environment for making sedimentary cover maps using the IDW interpolation method. The results showed similar sedimentation patterns in the dry season and in the rainy season. However, during the dry season, the highest presence of selected sediments was observed in high energy environments. Higher granulometry sediments were associated with channel beds and smaller granulometry sediments associated with mangrove margins. The highest levels of CaCo3 were found in the secondary channels of the locality of Portos dos Barcos, associated with fragments of shells and shells of marine animals. The highest levels of OM were found nearby, in mangrove areas and in regions where there is the greatest anthropic activity. This research works as a subsidy for future research and for the adoption of environmental management in this region, which suffers from the influence of human activity, making conservation actions and sanitation measures necessary, especially in the port region.