Bathymetric flow rectification in a tropical micro-tidal estuary

• Published in: Estuarine, coastal and shelf science Vol. 235; p. 106562
• Main Authors: Salas-Monreal, David, Riveron-Enzastiga, Mayra Lorena, de Jesus Salas-Perez, Jose, Bernal-Ramirez, Rocio, Marin-Hernandez, Mark, Granados-Barba, Alejandro
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 05.04.2020
• Subjects: Current rectification; Cyclonic recirculation; Hydrographic variability; Jamapa river estuary; Shallow micro-tidal estuaries; Veracruz reef system; Hydrographic variability; Jamapa river estuary; Current rectification; Cyclonic recirculation; Veracruz reef system; Shallow micro-tidal estuaries
• ISSN: 0272-7714; 1096-0015
• DOI: 10.1016/j.ecss.2019.106562

Temperature, salinity and current velocity data were recorded during the two principal atmospheric seasons affecting the tropical micro-tidal estuaries in the western Gulf of Mexico. Tropical micro-tidal estuaries in the western Gulf of Mexico share many characteristics, among them a narrow connection between the estuary and the adjacent continental shelf. Therefore, samples were taken during the dry (April 2009) and the rainy (July 2009) seasons, in order to elucidate the effect of the narrow connection between the estuaries and the continental shelf on flow dynamics. Due to the similarities between the tropical micro-tidal estuaries located in the western Gulf of Mexico, the Jamapa River estuary, a shallow estuary, with a narrow connection with the continental shelf and a ~5 m wide navigational channel, was used as a case study. During the dry season (April 15–17th, 2009) there was a surface horizontal displacement of the salinity and the temperature front of ~2 km, while during the rainy season (July 22–24th, 2009) the salinity and temperature gradients were mainly observed in the vertical at ~1 m depth. In this particular case, there was a marked difference between the northern and southern part of the estuary, due to the presence of a second river discharge (Arroyo Moreno), which discharges always stays in the northern part of the estuary (shallow area) owing to the influence of the navigational channel on fluid dynamics. Finally, a cyclonic recirculation was observed at the estuary mouth area. According to model outputs, the recirculation was observed when the ratio between the mouth and the estuary width were below 0.4, otherwise (>0.4) the recirculation was not observed. This should be a general behavior for all tropical micro-tidal estuaries located in the western Gulf of Mexico. •Tropical micro-tidal estuaries in the western Gulf of Mexico share many characteristics, among them a narrow connection between the estuary and the adjacent continental shelf. Here an analysis of widthoftheestuarymouthestuarywidth showed that when these value was below 0.4 there was a cyclonic recirculation induced by lateral constriction. Otherwise, the cyclonic recirculation was not observed.•Insity data at the Jamapa River estuary, used as a case study of a tropical micro-tidal estuary, showed the influence of the tides up to a distance of 4 km upstream, as well as the influence of the diurnal and the Msf tidal signal during the dry season, while during the rainy season the Msf signal was mask by the strong river discharges.•The river outflows, always stayed in the northern (shallow) part of estuary due bathymetric effects, inducing a marked difference of the salinity and temperature from the north to the south part of the estuary. This should be a common pattern in most tropical micro-tidal estuaries, therefore, they maybe different organism and flora, such as mangroves from one side to the other side (north to south) part of the estuary.•There was a lateral and vertical salinity and temperature gradient during the dry season, while during the rainy season there was only a vertical gradient. This variation was greater than the one found in most of the estuaries located in the western Gulf of Mexico.