Erosão Costeira no delta do Parnaíba

Atualizado: Abr 27

Saiu publicado no periódico Ocean and Costal Management (IF=2.482) um novo trabalho no âmbito do inctAmbTropic Fase II intitulado "Evaluation of decadal shoreline changes along the Parnaíba Delta (NE Brazil) using satellite images and statistical methods" de autoria de Thiago Augusto Bezerra Ferreira , André Giskard Aquino da Silva, Yoe Alain Reyes Perez, Karl Stattegger e Helenice Vital, que investiga o comportamento da linha de costa do delta do Parnaíba no período 1984-2017. O trabalho concluiu que a redução na descarga fluvial do rio Parnaíba entre 1995-1999 e 2009-2012 foi a causa principal do recuo erosivo experimentado pelo delta.

Comportamento da linha de costa do delta do Parnaíba entre 1984-2017. Vermelho: erosão. Verde: progradação.


This study investigated changes of the shoreline position in the Parnaíba River Delta (PRD), which is in an underdeveloped and sparsely populated area. The general behavior of the shoreline between 1984 and 2017 was analyzed using 12 Landsat satellite images and the Digital Shoreline Analysis System (DSAS) software. DSAS applied statistical methods, such as Weighted Linear Regression (WLR) and End Point Rate (EPR), to define whether the shoreline was retreating or accreting. Data analysis revealed that, on a decadal time scale (33 years), 52% of the PRD shoreline retreated under erosional conditions, while 48% accreted. Accretion mainly occurred at the vicinities of the river mouth, especially eastward where the highest progradation rate was observed (maximum of 29 m/year). Shoreline retreat, up to 9 m/year, occurred predominantly in the western part of the PRD and away from the river mouth. However, changes of the general behavior of the shoreline (retreat/accretion) were observed at an inter- decadal time scale, which were positively related to variations in river discharge. Variations of river discharge are directly dependent on the rainfall amount along the drainage basin that, in this region, is controlled by climatic conditions such as El Niño and La Niña. Therefore, the reduced river discharge observed between 1995- 1999 and 2009–2012 (El Niño periods), was the major cause the triggered the observed coastal retreat (>6 m/ year) on PRD shoreline during these periods. Consequently, the variability of natural factors, such as river discharge and rainfall, are the main drivers of shoreline changes on PRD, since anthropogenic impacts have hitherto only marginal effects on the delta region and on the drainage basin of the Parnaíba river.

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