Dinâmica da frente salina no canal norte do Rio Amazonas - Influência da vazão fluvial e da Faixa das Marés (Brasil)

Abstract

Part of the BARRANORTE project, this study analyzes the dynamics of saline intrusion in the Northern Channel of the Amazon River (0°50'N-1°50'N, 48°50'W-50°W). Monitoring the saline wedge helps locate regions with large deposits of sediment and contributes to the improvement of navigational and safety aids and environmental monitoring. Two campaigns were carried out in this study, in June 2006 (maximum fluvial discharge) and July 2007. Data were collected at six stations in 2006 and eleven in 2007, with 12 hours of measurements and a vertical profile taken every hour, covering half a tidal cycle. River flow and tidal data were obtained from the National Water Agency and Brazilian Navy, respectively. Surface winds were estimated using the QuikSCAT(NASA) scatterometer. The variation in the position of the saline wedge in the Northern Channel indicates significant variation on both a seasonal and a tidal cycle. The saline wedge was located 80 km from the mouth of the channel in minimal discharge conditions (data from the AMASSEDS project) and up to 120 km at maximum discharge (present study). Differences in this distance between 2006 (106 km) and 2007 (120 km) were probably related to those in the tidal regime, with data being collected during the neap tide in 2006 (H=2.4 m) and spring tide in 2007 (H=3.7 m). Saline stratification at the mouth of the Amazon varied from a wedge form (slightly stratified) at the neap tide to and partially mixed (highly stratified) at the spring tide