Circulation and salt balance in the São Francisco river Estuary (NE/Brazil)

• Autor(a) principal: Cavalcante,Geórgenes
• Data de Publicação: 2017
• Outros Autores: Miranda,Luiz Bruner de, Medeiros,Paulo Ricardo Petter
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: RBRH (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S2318-03312017000100222
• topic: Circulation; Salinity; Salt transport; Stratification; São Francisco Estuary

ABSTRACT In order to evaluate how river discharge and tidal currents forcing influence the circulation and salt transport within the São Francisco River-Estuary, a two 25 hour surveys campaigns and along-channel profiles were performed in the estuary main channel (18/19 and 25/26 February 2014). The current intensity showed higher asymmetry between flood (v<0) and ebb (v>0) currents in spring tide (-0.6 and 1.1 m/s), as compared to neap tide (-0.4 and 1.0 m/s), which was attributed to the intense buoyancy energy enhanced by the stronger discharge in spring. Overall, salinity presented high stratified conditions and varied between 0.0<S<36.6, and 0.5<S<36.1 from surface to bottom, during spring and neap, respectively. Although river discharge reduced from spring to neap tide partially mixed-highly stratified conditions (type 2b) remained in both periods, with advection and diffusion contributing with 34% and 66% to the net upstream salt flux in spring, respectively, and 56% and 44% in neap tide, respectively, which was attributed to the balance of tidal and baroclinic forcing and river discharge. The dominant downstream advective salt transport in both spring (12.5 kg.m-1s-1) and neap (15.2 kg.m-1s-1) tidal cycles suggests that there is little salt accumulation inside the São Francisco estuary.