Estuarine Bedforms and Hydrodynamic of the Piranhas-Açu River Mouth, Northeast of Brazil

Estuaries are important transitional areas as scientific as economic and environmental point of view. This study presents estuarine bedforms mapping associated with hydrodynamic data of the Piranhas-Açu River Mouth, where the river splits in three estuaries (Açu, Cavalos and Conchas), on the northern littoral of Rio Grande do Norte State, northeast of Brazil. The methodology used consisted of hydrodynamic and sonographic data acquisition in November of 2010, during the dry season, in spring tide. The main estuarines bedforms identified were: flat bed, small and medium 2D dunes and 3D dunes, produced in a lower regime, at depths range from 1 .5m to 8.0m with average speed flows from 0.2m/s to 1 .0m/s. The average speed flow on flood tide is around 0.5 m/s, and on ebb tide average between 0.8 and 0.6 m/s.