Validation of the 3D-MOHID Hydrodynamic Model for the Tagus Coastal Area

Abstract

The hydrodynamics of the TagusROFI (Regions of Freshwater Influence) is affected by the coastal upwelling, the estuarine tidal flow, the thermohaline circulation that is modulated by the Tagus freshwater discharge, and by its complex bathymetry. The use of numerical models is the best way to explain the processes that characterize this region. These models are also crucial to answer important scientific and management questions. Nevertheless, the robustness of the products derived from models depend on their accuracy and therefore models must be validated to determine the uncertainty associated. Time and space variability of the driving forces and of bathymetry enhance flow complexity increasing validation difficulties, requiring continuous high-resolution data to describe flow and thermohaline horizontal and vertical variabilities. In the present work, to increase the precision and accuracy of the coastal processes simulations, the sub-systems coastal area and the Tagus estuary were integrated into a single domain, which considers higher resolution grids in both horizontal and vertical directions. The three-dimensiosal (3D)-MOHID Water model was validated for the TagusROFI by comparing statistically modelling results with in situ and satellite L4 data. Validation with a conductivity, temperature, and depth probe (CTD), an acoustic doppler current profiler (ADCP) and satellite data was performed for the first time. Validation against tidal gauges showed that the model is able to simulate tidal propagation inside the estuary with accuracy. A very good agreement between CTD data and surface sea water temperature (SST) and salinity simulations was observed. The validation of current direction and velocity from ADCP data also indicated a high model accuracy for these variables. Comparisons between model and satellite for SST also showed that the model produces realistic SSTs and upwelling events. Overall results showed that MOHID setup and parametrisations are well implemented for the TagusROFI domain. These results are even more important when a 3D model is used in simulations due to its complexity once it considers both horizontal and vertical discretization allowing a better representation of the heat and salinity fluxes in the water column. Moreover, the results achieved indicates that 3D-MOHID is robust enough to run in operational mode, including its forecast ability, fundamental to be used as a management tool.

Saltwater Intrusion in the Upper Tagus Estuary during Droughts

“…Some studies addressed the salinity dynamics in the Tagus estuary, but the present knowledge of the salinity dynamics in the upper estuary remains limited. Most of the recent studies focused in the middle and downstream area of the estuary [18,22,23] and past studies of the A process-based model was previously implemented, calibrated and validated in the Tagus estuary [18] using the community model SCHISM [21]. That model is used herein to explore different scenarios of freshwater discharge and sea level rise and assess the saltwater intrusion in the upper reaches of the estuary.…”

“…Some studies addressed the salinity dynamics in the Tagus estuary, but the present knowledge of the salinity dynamics in the upper estuary remains limited. Most of the recent studies focused in the middle and downstream area of the estuary [18,22,23] and past studies of the upper estuary [24] did not take advantage of cross-scale simulation models, such as the one used herein. The previous implementation of SCHISM [18] is thus extended and applied herein to provide a better understanding of the salinity dynamics and its drivers in the upper Tagus estuary, in particular during droughts.…”

Hydrodynamic Model and Tidal Current Energy Potential in Lepar Strait, Indonesia

“…The study location is the Lepar Strait, situated between Bangka and Lepar Islands, illustrated in Figure 1(c). Administratively, it is part of the South Bangka Regency in the Province of Bangka-Belitung Archipelago (BPS Kabupaten Bangka Selatan, 2020). At the side of Bangka Island, various land uses can be found, including salt ponds.…”

The Tagus Estuary as a Numerical Modeling Test Bed: A Review

“…This study sets the main horizontal distribution patterns of salinity and water temperature in response to different wind conditions, namely upwelling and downwelling favorable (as depicted in Figure 10). Another work sets an operational 3-dimensional model for the estuary and its region of freshwater influence [88]. The main objective of this study was to perform simulation of the Tagus continuum, both in hindcast and forecast modes, providing high-resolution outputs for the hydrodynamics and water quality parameters of the region.…”