Table of Contents
International Journal of Oceanography
Volume 2013 (2013), Article ID 315328, 10 pages
http://dx.doi.org/10.1155/2013/315328
Research Article

Effects of Tidal Range Variability and Local Morphology on Hydrodynamic Behavior and Salinity Structure in the Caeté River Estuary, North Brazil

1Universidade Federal de Alagoas, Instituto de Ciências Atmosféricas, CEP 57072-970, Maceió, AL, Brazil
2School of the Environment, University of Technology, Sydney, P.O. Box 123, NSW 2007, Australia
3World Maritime University, P.O. Box 500, S-20 124 Malmö, Sweden

Received 12 April 2013; Accepted 18 July 2013

Academic Editor: Renzo Perissinotto

Copyright © 2013 Geórgenes H. Cavalcante et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Tidal influence and local morphology on circulation and salt transport are investigated in the Caeté river estuary, a well-mixed estuary along the north coast of Brazil. Velocity, temperature, and salinity data were collected in three different locations along the estuary’s main channel, over three single, 13 h tidal cycles. The aim of this study was to investigate the relationship between tidal distortion and salinity by using classical methods of comparison of three cross-channel circulation characteristics, as well as computation of salt flux and vertical mixing. Findings indicate a flood-ebb asymmetry in currents, due to the distinct funneling morphology of the estuary, with shallow marginal areas being dominant towards the estuary head, while both stratification and shear dominate near the estuary mouth. The tidal currents enhanced vertical diffusion in the mid- and lower reaches, explaining the prevailing weakly stratified conditions, while the dominant well-mixed conditions in the upper estuary are a result of a combination of stronger flood currents and negligible vertical saline gradient. The predominant downstream salt transport supports the conclusion that there is little accumulation of salt in the Caeté river estuary. In addition, findings indicate that tidal correlation and Stokes drift are important components in the upper estuary, while tidal correlation played an important role in the middle estuary, with fluvial discharge most important in the lower estuary.