Evaluation of decadal shoreline changes along the Parnaíba Delta (NE Brazil)
Remote Sensing; Parnaíba River Delta; Digital Shoreline Analysis; Erosion; undeveloped delta
The coastal zone are transitional environments, where continuous changes at different temporal and spatial scales occur, which are related to several processes such as oceanographic, fluvial, climatic and anthropogenic. Continuous monitoring of this environment provides essential information for understand the spatial distribution of erosive/depositional patterns, hence, its development. The main objective of this research was to investigate the Parnaiba River Delta’s shoreline behavior, at short and intermediate time scale, between 1984 and 2017, through 12 Landsat satellite imagens and statistical software (Digital Shoreline Analisys System). At intermediate scale, the results showed that 21% of PRD’s beaches are under intense shoreline retreat, 30% moderate shoreline retreat, 4% are stable, 29% moderate shoreline progradation and 15% under intense shoreline progradation. At short intervals, shoreline variations are directly related to the climatic hydro influence in the drainage basin, specifically with the El Niño and La Niña effects. On both time scales, major erosion trend occurred away from Parnaiba River mouth and predominantly on the west side of the delta, while deposition, or stability, prevailed on the east side. Due to lower anthropogenic impacts, both on coastal zone and the drainage basin area, the natural factors, mainly river discharge and rainfall trends, are likely to be main driving forces of shoreline changes between 1984 and 2017.