Author(s): Manel Grifoll; Jarle Berntsen; Alan Cuthbertson; Carles Ibanez; Agustin Sanchez-Arcilla
Linked Author(s): Alan J S Cuthbertson, Agustín Sánchez-Arcilla
Keywords: Salt-wedge estuary; Ocean modelling; Bidirectional flow; Salt intrusion; Ebre Delt
Abstract: In some wave-dominated deltas, the formation of a delta front, such as a submerged mouth bar, is primarily related to the prevalent along-shore hydrodynamics and sediment dynamics. The near mouth bathymetry of the Ebre and Rhone Deltas (both located in the NW Mediterranean Sea) presents these submerged bar features (Ibanez et al., 1997), with an expected obstruction on the salt wedge dynamics (i. e. generated by a strong density interface) and salt intrusion into the upstream estuary. In this contribution, we investigate the impact that these submerged sand bars can have on salt-wedge intrusion (with implications for dredging regimes, changes to longterm morphodynamics, and the potential for the complete blockage of estuarine exchange flows). In addition, the effect of climate change may also alter the submerged bar morphology due, for example, to a decrease in the river flow (and sediment load), as a consequence of extreme drought conditions expected in the near future, or as a result of the increasing prevalence of storm surges and waves which may modify the sand bar dynamics. The current study aims to explore, using hydrodynamic numerical modeling, the regulation of fresh-saline water exchange flows into semi-enclosed estuaries, and the impact on the salt wedge intrusion due to the presence of an sand bar obstruction.
Year: 2024