River–coastal–ocean continuum modeling along the Lazio coast (Tyrrhenian Sea, Italy): Assessment of near river dynamics in the Tiber delta

The complex processes that occur in river delta areas cannot be fully resolved using traditional structured-mesh models. A seamless unstructured-grid approach could support advances in the estimation and modeling of such dynamics across scales. In this paper, a river–coastal–ocean continuum modeling representation was developed for the Tiber River delta, including surrounding coastal areas and open-ocean zones along the Lazio coast (Tyrrhenian Sea, Italy). Using temperature and salinity profiles acquired from historical data of near-river CTD, we demonstrate that this representation reproduces the coastal dynamic processes in the Tiber delta zone better than the classic coastal–ocean representation, minimizing the need for calibration and sensitivity experiments. The model results are compared to a large amount of new observational data (temperature, salinity, and surface currents) obtained specifically to investigate multiple spatial and temporal processes (open-ocean, coastal and near- and along-river). In general, the model shows good overall accuracy, also in reproducing salt wedge intrusion along the southern Tiber branch. Moreover, the results suggest the presence of an anticyclonic gyre in the vicinity of the river mouth of the northern branch that is induced mainly by river discharge and coastal morphology. Owing to its capacity to simulate multi-scale processes in a seamless fashion from the open ocean to the river delta zone, this model can be implemented in the near future within an operational framework to support coastal forecasting activities and deliver useful and reliable ocean information.