Spatial-temporal dynamics of coastline associated with ebb tidal delta, Cacha Pregos e Ponta dos Garcez, Bahia, Brazil

Abstract

The work investigated the coastline behavior of two beaches contiguous to an ebb tidal delta, in Bahia, Brazil. The spatial-temporal dynamics were evaluated using historical (satellite images) and seasonal (field geoindicators) data. The medium-term qualitative analysis (1984 to 2020) showed that the coastline retreated or prograded due to changes in configuration of inlet bars and the main ebb channel. The medium-term quantitative analysis (2003-2019) highlighted the importance of littoral transport cells on sediments dispersion along the coast. In the short-term analysis (seasonal), during La Niña years (2021-2022), a behavior trend of estuarine and oceanic high variability morphology coastlines was not verified. Additionally, the presence of a medium and short-term sediment reservoir was identified, which causes the sediments to recirculate, mainly on high variability parts. Finally, the Cacha Pregos estuarine beach, with protection structures, showed chronic (irreversible) erosion. The other places, with acute erosion, comprise unoccupied areas, which can recover naturally. The work serves as subsidies for the environmental planning of coastal zones.