Analysis of Antropogenic effects on the tidal dynamics and salt transport along the Guadalquivir river estuary.

This study presents an analysis of the impacts of changes in bottom depth along the Guadalquivir Estuary on tidal dynamics. A realistic non-linear 1D numerical model, incorporating alterations in both breadth and bottom depth, was employed to investigate the associated effects.The 1D numerical model consists of a hydrodynamical model and a transport and dispersion module,which successfully reproduce the hydrodynamics of the saline intrusion from the continental shelf.The results show a significant amplification of the M2 tidal wave towards theheadof the Estuary,which seems to be caused bythe gradual bottom deepening caused by multiple dredging activities. The Estuary exhibits a pronounced tendency towards resonance, which is further enhanced by this deepening which reduces bottom friction and produces a smaller decrease in tidal wave amplitude as it propagates through the Estuary. The alterations in depth, particularly in breadth, along the Estuary play a crucial role in determining the magnitude of the resonant response of the M2 tidal wave.Modelsimulations demonstrate how changes in the geometric configuration of the channel, as well as the river waterwithdraw different agricultural activities, lead to significant alterations in the salt wedgedynamics. These changes in the tidal and associated salt exchange dynamics may also have a significant impact in thebiogeochemical exchanges between the river and the continental shelf, with potential harmful effect on the primary productionin the mouth of the estuary and adjacent coastal areas.