%0 Journal Article
%T Intra-tidal variation of stratification in a semi-arid estuary under the impact of flow regulation
%A Felipe Fac¨® Frota
%A B¨¢rbara Pereira Paiva
%A Carlos Augusto Fran£¿a Schettini
%J Brazilian Journal of Oceanography
%D 2013
%I Universidade de S?o Paulo
%X The Jaguaribe River is the largest semi-arid Brazilian river and represents an important water source for the state of Cear¨¢. The Castanh o Weir, built to regulate the flow of the Jaguaribe, began operating successfully in the 1990s. As a result, the hydrodynamic regime of the estuary has undergone alteration and is no longer subject to the former annual climatological variability of the dry and rainy seasons. This paper introduces an assessment of the changes in the hydrological conditions resulting from the construction of the weir and investigates the structure of the density stratification in the estuary. A field experiment was conducted at the end of the dry season in November 2009, during which salinity and temperature were monitored at different levels for three tidal cycles. The temporal variations in salinity and temperature during the tidal cycles were 16 psu and 1.5¡ãC, respectively. The salinity exhibited a vertical variation of four units, while the temperature variation was much lower. Several stratification indicators were calculated from the observed density: the stratification coefficient, the Brunt-V is l  frequency and the potential energy anomaly. The results showed that the parameters behave similarly, differences being observed only in their relative magnitudes. The vertical structure of the estuary exhibited marked stratification during the ebb tide but vertical homogeneity during both flood and high tide. With the regularized flow existing under present conditions, the estuary exhibits hyposaline and a partially mixed structure for the period studied, despite the typical expectation of a hypersaline and well-mixed vertical structure. O rio Jaguaribe ¨¦ o maior rio do semi-¨¢rido brasileiro, constituindo uma importante fonte de ¨¢gua para o estado do Cear¨¢. Na d¨¦cada de 1990 entrou em opera  o o A ude do Castanh o com o objetivo de regularizar a vaz o do rio Jaguaribe, o qual obteve grande sucesso. Como consequ¨ºncia foi alterado o regime hidrodinamico do estu¨¢rio, o qual atualmente n o est¨¢ mais sujeito a variabilidade climatol¨®gica anual de esta  es seca e chuvosa. O presente trabalho apresenta uma avalia  o da mudan a do regime hidrol¨®gico antes e ap¨®s a constru  o do a ude, e investiga a estrutura de estratifica  o da densidade nos estu¨¢rios. Foi realizado um experimento de campo em novembro de 2009, no fim da esta  o seca, quando a salinidade e temperatura da ¨¢gua foram monitorados em diferentes n¨ªveis durante tr¨ºs ciclos de mar¨¦. A varia  o temporal da salinidade e temperatura durante os ciclos de mar¨¦ foram de 16 psu e 1,5oC, re
%K Hidrodinamica estuarina
%K A ude
%K Barramento
%K Gerenciamento de recursos h¨ªdricos
%K Rio Jaguaribe
%K Cear¨¢
%K Estuarine hydrodynamics
%K Weir
%K damming
%K Water management
%K Jaguaribe River
%K Cear¨¢
%U http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-87592013000100003