Alterações morfológicas e evolução da carcinicultura no Sistema Lagunar de Guaraíras - RN

This paper presents a spatio-temporal analysis of the Guaraíras Lagoon System (Rio Grande do Norte State, Brazil) focusing on its morphological changes and the shrimp farming expansion over the last 32 years. The local history is marked by an abrupt transition of its ecosystem about hundred years ago, that has transformed its ecological, morphological and socio economic characteristics till current days. The investigation was based on the complete collection of Landsat 5 TM and Landsat 8 OLI imagery, from 01/01/1985 to 10/31/2016. Data processing was performed using Google Earth Engine platform (cloud computing) and ArcMap 10.2.2 software. Eight mosaics - adopting reduced cloud coverage (minimum Cloud Score) at four-year intervals - were generated to compose RGB colored images using spectral bands: SWIR, NIR and Blue. Such combination highlighted shorelines and contrasted bodies of water. Areas computed by supervised classification were compared to the areas computed by orthophotos vectorization (2,0 m spatial resolution). The results pointed an intense erosive process at the inlet channel at an average retreat rate of 6.84 m/year (measured on the region of greatest change). It could also be observed an expressive expansion of the shrimp farming activity around the entire lagoon system at an average growth rate of 30.3 ha/year. Currently it covers a total area of 1,528.1 ha.