A coastal flooding database from 1980 to 2018 for the continental Portuguese coastal zone

Continental Portugal presents an extensive and diversified coastal zone which concentrates the main public and private infrastructures of the different economic sectors, as well as the main critical infrastructures. This area is also characterized by a high population density, being a differentiated territory in geophysical, biological and landscape terms. The wave regime is highly energetic, and storms are frequent. In the last decades, the coast of continental Portugal has been affected numerous times by overtopping and coastal flooding processes. Identifying the critical coastal typologies affected by flooding can contribute to a comprehensive flood risk management framework for the Portuguese coastal zones. Hence, a historical database of coastal flooding occurrences was created for the period 1980–2018 based on national and regional newspapers. For this period 650 occurrences were identified as well as 1708 impacts associated with them. In terms of impacts, the typologies associated with public areas, human impacts, the natural system, environmental degradation and buildings stand out. Results provide relevant temporal and spatial information about coastal historical flood occurrences related to extreme storm events and associated impacts, and contribute to the design of a risk framework.info:eu-repo/semantics/publishedVersio

Chapter 12 - Modelling the effects of climate change in estuarine ecosystems with coupled hydrodynamic and biogeochemical models

Estuaries are among the most productive ecosystems on Earth and provide multiple ecosystem services. They harbor ecologically important habitats for fish, shellfish, and birds and support diverse human activities (e.g., marine transportation, fishing, and tourism). However, climate change, together with the predicted increase of human activities, may increase the hazards in these systems and alter estuarine ecosystems dynamics. Coupled hydrodynamics and biogeochemical numerical models, which jointly simulate the physical, chemical, and biological processes at the relevant spatial and temporal scales, are useful tools to support climate change impact studies on estuarine ecosystems dynamics. A general overview of some well-established coupled hydrodynamic–biogeochemical models is presented and their use to support the study of climate change impacts on estuarine ecosystems is discussed. The use of coupled hydrodynamic–biogeochemical models to support the long-term, climate-adapt management of estuarine ecosystems and the definition of mitigation and adaptation strategies within a climate change context is demonstrated with a case study: the evaluation of climate change impacts in the lower trophic levels dynamics in the Aveiro lagoon using the model ECO-SELFE. Existing coupled hydrodynamic–biogeochemical models already have numerous benefits in climate change impact studies. Future research should improve these models’ capabilities to reduce limitations and uncertainties, in particular those related to the coupled representation of the physical and biological processes and their feedbacks over long time scales.info:eu-repo/semantics/publishedVersio

The complexity of the coastal zone: definition of typologies in Portugal as a contribution to coastal disaster risk reduction and management

Mainland Portugal presents an extensive, diversified and complex coastal zone. This diversity gives rise to diverse geomorphologic features which support different densities of human occupancy and a range of land uses and activities. In this sense, the coastal zone becomes an area of great national strategic value, but has also into a multi-hazard zone. To understand this complexity, two statistical techniques, namely Cluster Analysis and Principal Component Analysis, were used to identify and differentiate, between the different coastal typologies, based on a set of variables that express the territorial complexity and the occurrences and impacts of coastal flooding. The chosen methodology enabled a diverse set of coastal typologies to be identified, which contributes towards differentiating local specific characteristics. The holistic and differentiating nature of the applied methodology and the results obtained allows it to contribute to the definition of mitigation strategies and the implementation of adaptation measures. The results enable us to define a set of typologies associated with Coastal Disaster Risk Reduction and Management which are an important contribution to comprehensive coastal flood risk assessment and management.info:eu-repo/semantics/publishedVersio

Evolution of the hydrodynamics of the Tagus estuary (Portugal) in the 21st century

The ongoing rise in sea level affects tidal propagation and circulation in estuaries, and these changes can have far reaching consequences on the sediment dynamics, water quality and extreme water levels. This study aims at anticipating the evolution of the tidal dynamics in the Tagus (Portugal) in the 21st century, in particular due to sea level rise (SLR). The existence of a resonance mode of about 8 hours in this estuary, that selectively amplifies both semi-diurnal and quarter-diurnal tidal constituents, makes the response of the Tagus estuary to SLR unique. The study was conducted with a shallow water model, forced by present and future conditions, namely higher mean sea levels and an extrapolated bathymetry based on present sedimentation rates. Model results showed that SLR will significantly affect tidal asymmetry, in particular because the intertidal area can decrease by up to 40% by the end of the 21st century. As a result, the strong ebb-dominance of this estuary will decrease significantly. This evolution of tidal asymmetry will be counteracted by the effect of sedimentation of the salt-marsh areas. Also, SLR will enhance the resonance in the Tagus estuary. As a consequence, extreme water levels will be higher than the sum of present levels with the SLR

Water exchanges between a multi-inlet lagoon and the ocean: the role of forcing mechanisms

Understanding the influence of the main drivers controlling the circulation and the transport in coastal lagoons is a necessary step towards the description of the dynamics of their ecosystems. Thus, the influence of the main physical drivers on the water exchanges in a multi-inlet barrier island (western sector of the Ria Formosa coastal lagoon, Portugal) was investigated. Several scenarios of tide, wind, bathymetry and point source discharges were simulated using a three-dimensional circulation model and a particle-tracking model. The circulation is adequately reproduced by the hydrodynamic model, with root mean square errors of about 5-8 cm for the water levels and 5-10 cm/s for the cross-sectional averaged velocities in the western inlets and main channels. Wind has a negligible effect on the modelled water levels and cross-sectional velocities, with differences smaller than 1 % between the simulations with and without wind. However, results show that wind influences significantly the transport by affecting the residual circulation, with distinct effects depending on the wind direction. Upwelling favourable winds (with west component) increase the landward transport through the Faro-Olho inlet and promote a larger dispersion of the water-borne material inside the lagoon. The residual circulation between the three inlets of the western sector of the lagoon is also significantly affected by the bathymetry. Results show a decrease of about 50 % of the tidal prism of the Anco inlet between 2002 and 2011, which reduces its capacity to export waterborne material to the adjacent coastal area and increases the residence times in some areas of the lagoon, with potentially adverse effects on the ecosystems' health. The dispersion of potential contaminants from point sources inside the lagoon to the coastal area depends on the combined effect of the tidal phase and amplitude and the location of the source. Mean residence times for the discharges from the wastewater treatment plants of the western sector ranged from 7 to 18 days. These findings improve the understanding of the influence of the physical forcings in the circulation and transport dynamics of multi-inlet coastal systems