Coastal evolution analysis between the years 1984 and 2014 on a stretch of rio grande do norte eastern coast, northeast Brazil

Abstract

Coastal areas plays an important role in socioeconomic development on all continents and for this reason, more and more the anthropic pressure rises in these areas. This gradual and disorderly growth causes an increase in environmental vulnerability in these areas, putting at risk both the preservation of the environment and activities of socioeconomic interest. This occurs because, in coastal zones, there are ecosystems of high environmental sensitivity that show significant changes in short intervals of time. In this context, the State of Rio Grande do Norte (RN), which has tourist cities equipped with dense coastal infrastructure have presented problems with the coastal dynamics over the last decades. In light of this, this study aimed to develop methods in Geoprocessing that allowed the evaluation of the evolution of the shoreline in a stretch of sandy beach of 12 km on the eastern coast, thus providing some of the necessary information for the management and maintenance of these areas. For this, were used satellite images of the Landsat series of four different decades (1984, 1994, 2004 and 2014), which, though uses of automatic techniques, allowed the definition of shoreline evolution over 30 years. These shorelines were used in the statistical modules of Digital Shoreline Analysis System (DSAS) to generate four different analyzes (1984 to 1994, 1994 to 2004, 2004 to 2014, and 1984 to 2014) that were evaluated about the change rate, amplitude and mobility of shoreline. The analysis showed deposition episodes (mean of +0.7 m / year) from 1994 to 2004 and episodes of erosion from 1984 to 1994 (mean of -0.9 m / year) and from 2004 to 2014 (mean of -0.5 m / year). Such succession of depositional and erosional events shows a relative stability for this sector of the eastern coast; however, there is a clear erosive trend (mean of -0.5 m / year) that shows that the coastal erosion, although not as significant as in other areas of the state, requires attention in the sectors where there is urban infrastructures built.