Browsing by Author "Garcia-Lafuente, Jesus"
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- Effects of tidal and river discharge forcings on tidal propagation along the Guadiana EstuaryPublication . Calero Quesada, Maria Concepcion; Garcia-Lafuente, Jesus; Garel, Erwan; Delgado Cabello, Javier; Martins, Flávio; Moreno-Navas, JuanA numerical model is implemented to explore the effect of the river discharge on tidal propagation along the Guadiana Estuary, a rock-bound estuary located in Southwest Iberia. The MOHID numerical model, in 2D barotropic mode, has been forced by tides at the ocean side and by freshwater at the upstream boundary of the domain. The model was validated using water level and velocity observations at several locations along the estuary. Different scenarios with variable tidal forcings and freshwater discharges were analysed, considering the semi- diurnal constituents and M4 overtide, in order to assess the influence of each external agent on the along-channel hydrodynamics. The model reproduces the expected general tidal properties along the channel in terms of amplitude (of both elevation and current), asymmetry and phase between horizontal and vertical tides. Three zones along the estuary have been defined based on the overtide patterns. Tidal propagation in Zone I, at the lower estuary, vary essentially with the tidal amplitude at the mouth while changes due to river discharge are minor. Along Zone II (middle estuary), the tidal forcing still predominates, for low discharge values only. Along Zone III (upper estuary), the tidal propagation is primarily controlled by the river discharge. Although the discharge threshold vary with the location and parameter considered, it is estimated that a discharge as little as 100 m3/s has a strong effect on the tidal properties along the system as a whole. It is therefore concluded that tidal properties in rock-bound estuaries may be importantly modified by relatively weak river discharge events.
- The mediterranean overflow in the Gulf of Cadiz: a rugged journeyPublication . Sanchez-Leal, Ricardo F.; Jesus Bellanco, Maria; Miguel Fernandez-Salas, Luis; Garcia-Lafuente, Jesus; Gasser-Rubinat, Marc; Gonzalez-Pola, Cesar; Hernandez-Molina, Francisco J.; Pelegri, Josep L.; Peliz, Alvaro; Relvas, Paulo; Roque, David; Ruiz-Villarreal, Manuel; Sammartino, Simone; Carlos Sanchez-Garrido, JoseThe pathways and transformations of dense water overflows, which depend on small-scale interactions between flow dynamics and erosional-depositional processes, are a central piece in the ocean's large-scale circulation. A novel, high-resolution current and hydrographic data set highlights the intricate pathway travelled by the saline Mediterranean Overflow as it enters the Atlantic. Interaction with the topography constraints its spreading. Over the initial 200 km west of the Gibraltar gateway, distinct channels separate the initial gravity current into several plunging branches depth-sorted by density. Shallow branches follow the upper slope and eventually detach as buoyant plumes. Deeper branches occupy mid slope channels and coalesce upon reaching a diapiric ridge. A still deeper branch, guided by a lower channel wall marked by transverse furrows, experiences small-scale overflows which travel downslope to settle at mid-depths. The Mediterranean salt flux into the Atlantic has implications for the buoyancy balance in the North Atlantic. Observations on how this flux enters at different depth levels are key to accurately measuring and understanding the role of Mediterranean Outflow in future climate scenarios.