Modelling the Main Hydrodynamic Patterns in Shallow Water Estuaries: The Minho Case Study

Isabel Iglesias,Paulo Avilez-Valente,Ana Bio,Luísa Bastos

doi:10.3390/w11051040

Isabel Iglesias, Paulo Avilez-Valente + Show 2 more

Open Access

https://doi.org/10.3390/w11051040

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Abstract

Numerical models are key tools to characterize hydrodynamical patterns of coastal environments and anticipate the potential effects of hazardous and extreme events, anthropogenic intervention or climate change. In this work, the openTELEMAC-MASCARET modelling system was selected to represent the dynamics of the Minho estuary, a very shallow estuary located at the Northwestern Iberian Peninsula coast. Calibration and validation results confirm the accuracy of the numerical tool, with small root mean square errors, close to null bias and the close to unit correlation and skill coefficients obtained for water level and currents velocity at several estuarine locations. The obtained results depict a tide dominated estuary with a delay in the tide phase and a marked asymmetry in the tide curve that increases upriver. Additionally, an upstream diminution of M2 and an upstream augmentation of M4 was observed, classifying this estuary as flood-dominated. The represented current patterns show that variations in the intensities of the main driving forces alter the behaviour of the hydrodynamical patterns within the estuary, with a clear dependence on bathymetric and topographic characteristics. During flood events, larger estuarine regions become submerged due to the low margins and the wetland characteristics, highlighting the need for accurate numerical models that can be used as a decision-making support tool for effective and integrated estuarine management.

Highlights

Estuarine areas have been intensively studied, on one hand, given the importance of their ecosystem services for human populations living on their margins and, on the other, because of the increasing anthropic impact which can boost the local vulnerability [1]
The represented current patterns show that variations in the intensities of the main driving forces alter the behaviour of the hydrodynamical patterns within the estuary, with a clear dependence on bathymetric and topographic characteristics
The works of Horrit and Bates [36], Hu et al [37], Néelz and Pender [38,39], Robins and Davies [34], Monteiro et al [35], Wan et al [40], Symonds et al [41] and Iglesias et al [6] demonstrate that 2DH models are capable of adequately predicting velocity, flood extent and water level, proving that 2DH models results are suited for risk assessment. 2DH models are widely used by the scientific community to represent the hydrodynamics of shallow estuarine systems, reinforcing their applicability for the Minho estuary region [14,42,43]

Summary

Introduction

Estuarine areas have been intensively studied, on one hand, given the importance of their ecosystem services for human populations living on their margins and, on the other, because of the increasing anthropic impact which can boost the local vulnerability [1]. Estuaries are complex systems where the coupled geological, hydrodynamic, geochemical and biological processes, and the interaction between the fluvial watershed and the coastal zone are modulated by several forcing mechanisms. The main hydrodynamic forcing drivers in these transition systems are wind shear stress, waves, tides, freshwater inflow, temperature and salinity gradients, and exchanges with the atmosphere [2]. The relative importance of the forcing drivers will, depend on the unique characteristics of each estuary and associated ecosystems [3]. Estuaries present a tightly coupled relation between morphodynamics and hydrodynamics.

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