Análise da evolução costeira para as praias de Muriú e Jacumã, litoral oriental do Estado do Rio Grande do Norte, Nordeste do Brasil, por meio do DSAS e SMC-Brasil

Abstract

Coastal zones are studied by several areas of science, either because of their socioeconomic importance in the emergence and development of society, or because of the environmental importance of these fragile transitional environments located between continental and marine domains. Currently, demographic growth and the occupation rising of these areas has been the object of higher attention worldwide due to the severity of the damages caused by the rapid changes resulting from the interaction of waves, tides and currents with the coastal morphology. Allied to the lack of planning in the occupation of these areas, there is still a great gap in the studies carried out on the processes and variables inserted in this environment, which exposes to danger the balance between the development of social and economic value activities and the preservation of the unique ecosystems developed in these regions. The study of the coastal zone is based on the observation and analysis of the seasonal changes of these areas that, due to their high environmental sensitivity, are subject to modifications that are often irreversible. In this context, the State of Rio Grande do Norte includes tourist cities equipped with dense coastal infrastructure that over the years presents more and more problems related to the coastal dynamics, especially regarding to erosion of sandy beaches. In this context, the present study aimed to analyze the evolution of Muriú and Jacumã beaches, eastern coast of Rio Grande do Norte, using the Digital Shoreline Analysis System (DSAS) and the Coastal Modeling System (SMC). The use of these tools allowed the analysis of the variation, amplitude and mobility of the shoreline between 1984 and 2014 and the characterization of the bathymetry, wave climate, currents and sediment transport during the 60 years (1948 - 2008). Finally, information from the DSAS and SMC were integrated, providing the volumetric variation between 1984 and 2014.The analysis allowed the identification of deposition episodes (mean of +0.7 m / year) from 1994 to 2004 and erosion episodes from 1984 to 1994 (mean of -0.9 m / year) and from 2004 to 2014 (mean of -0.5 m / year). In addition, it was possible to determine the hydrodynamic characteristics (predominance of east-southeast direction waves and southeast direction currents), as well as morphological characteristics (sediment transport rate of 54,000 m³ / year (SMC) and 64,000 m³ / year (DSAS-SMC)). The study of Muriú and Jacumã beaches allowed to construct a greater understanding of the processes involved in the coastal evolution of these beaches. In addition, it allowed the visualization of the active dynamics and the identification of the sectors of greater sensitivity and susceptibility to changes, thus providing relevant information to the management and maintenance and preservation of the area under study.