Lisbon, Portugal
Lisbon, Portugal

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Povoa P.,Simtejo | Nobre A.,Simtejo | Leitao P.,Hidromod | Galvao P.,Hidromod | And 4 more authors.
Water Science and Technology | Year: 2015

Managing combined sewage systems in large cities discharging to coastal waters, often bearing recreational activities, remains a challenge. Studying the impacts of such discharges requires the development of specific models. Hydrodynamic and water quality modelling of coastal waters employs numerical methods and algorithms, leading to the design of complex models which require expert use. The use of such models as decision support tools to simulate discharge impacts and define adequate corrective measures could represent a key part in meeting this challenge. In this paper, the authors describe the work undertaken to develop an operational decision support system (ODSS) methodology aiming to enable wastewater utilities' non-expert staff to carry out user-friendly scenario analysis based on computational fluid dynamics simulations. This article depicts the application and validation of the ODSS to the combined sewage system and the Tagus estuary of the city of Lisbon in Portugal. The ODSS was used for simulating the effects in the receiving coastal waters of a discharge caused by a scheduled maintenance operation in the sewage infrastructure. Results show that the use of such ODSS by non-expert staff increases their decision capabilities and knowledge of the wastewater utility's contribution to reducing negative impacts of sewage discharges on the receiving water bodies.


PubMed | Simtejo, University of Lisbon and Hidromod
Type: Journal Article | Journal: Water science and technology : a journal of the International Association on Water Pollution Research | Year: 2015

Managing combined sewage systems in large cities discharging to coastal waters, often bearing recreational activities, remains a challenge. Studying the impacts of such discharges requires the development of specific models. Hydrodynamic and water quality modelling of coastal waters employs numerical methods and algorithms, leading to the design of complex models which require expert use. The use of such models as decision support tools to simulate discharge impacts and define adequate corrective measures could represent a key part in meeting this challenge. In this paper, the authors describe the work undertaken to develop an operational decision support system (ODSS) methodology aiming to enable wastewater utilities non-expert staff to carry out user-friendly scenario analysis based on computational fluid dynamics simulations. This article depicts the application and validation of the ODSS to the combined sewage system and the Tagus estuary of the city of Lisbon in Portugal. The ODSS was used for simulating the effects in the receiving coastal waters of a discharge caused by a scheduled maintenance operation in the sewage infrastructure. Results show that the use of such ODSS by non-expert staff increases their decision capabilities and knowledge of the wastewater utilitys contribution to reducing negative impacts of sewage discharges on the receiving water bodies.


Campuzano F.J.,University of Lisbon | Pierini J.O.,Comision de Investigaciones Cientificas CIC | Leitao P.C.,Hidromod | Gomez E.A.,Comision de Investigaciones Cientificas CIC | Neves R.J.,University of Lisbon
Journal of Marine Systems | Year: 2014

The Bahía Blanca estuary is a complex system of channels and tidal flats where the most important deep water harbour system of Argentina is located. The main goal of the present work was to obtain a hydrodynamic conceptual model for the Bahía Blanca coastal area. For this reason, a combined analysis of observed data and numerical modelling has been performed for the whole area. The gained knowledge on the system hydrodynamics could aid in the decision support for navigation security, waste water discharges management, sediment dredging and rejection operations among other applications.Due to the Bahía Blanca coastal vast area, hydrodynamic observations are scarce and located near the populated areas. In order to describe the hydrodynamics of such a complex and large system, the analysed tidal and current data from different periods have been completed through numerical modelling.Data analysis served to determine the main processes governing the Bahía Blanca hydrodynamics, to characterise the area using general descriptors, to provide inputs for the numerical model and to aid in evaluating its performance. In addition, a 2-dimensional application was set up using the MOHID water modelling system for the Bahía Blanca estuary. This application aimed to gain a better understanding of the system dynamics, to explain and test the consistency of the observed data and to reproduce the processes taking place.Model results were in good agreement with the analysed data and served to confirm an inconsistency found on the sea level observations. The combination of both methodologies served to further describe the hydrodynamic processes governing this coastal area and also to obtain a conceptual model for the water and property circulation in the Bahía Blanca estuary. © 2013 Elsevier B.V.


Vaz N.,University of Aveiro | Mateus M.,University of Lisbon | Plecha S.,University of Aveiro | Sousa M.C.,University of Aveiro | And 3 more authors.
Journal of Marine Systems | Year: 2015

This work studies the influence of the Tagus estuary, Portugal, on the near coastal system using a model application to describe the main physical and biogeochemical processes in the Region of Freshwater Influence (ROFI). It was used as nested modeling approach, downscaling the solution for the general circulation from a larger domain model (the Portuguese coast), to the local Tagus estuary domain. The model is evaluated during a very dynamic and biologic productive period of the year, corresponding to the winter and early summer (January-May 2007). Also during this period, there is a strong freshwater inflow into the Tagus estuary, which in turn modulates the estuarine outflow to the Tagus ROFI. The results focus on water temperature and chlorophyll and a skill assessment was made, given the lack of data required to perform a thorough validation.Simulation results reveal an adequate reproduction of the vertical thermal structure and chlorophyll concentrations. While a fairly reasonable agreement is seen for water temperature, showing no significant thermal stratification at the study area (average surface-to-bottom difference ranging from 1.3°C to 1.6°C), chlorophyll vertical profiles show some differences between the model results and the measurements. Maximum model bias for surface temperature is 1.4°C and ranges from 1 to 2mgm-3 for chlorophyll, revealing an underestimation of the predicted chlorophyll and surface temperature for the area in the vicinity of the Tagus mouth. The general trends of surface chlorophyll and surface water temperature are satisfactorily reproduced by the model. © 2014 Elsevier B.V.


Franz G.A.S.,University of Lisbon | Leitao P.,HIDROMOD | dos Santos A.,University of Lisbon | Juliano M.,University of The Azores | Neves R.,University of Lisbon
Brazilian Journal of Oceanography | Year: 2016

The applicability of a numerical model following a downscaling methodology was evaluated for the south-eastern Brazilian shelf (regional model) and Paranaguá estuarine system (local model). This approach permits the simulation of different scale processes, such as storm surges and coastal upwelling, and is suitable for operational forecasting purposes. When large areas are covered by regional models, the tidal propagation inside the domain can be significantly affected by the local tidal potential, mainly where the resonance phenomenon is observed. The south-eastern Brazilian shelf is known for the resonance of the third-diurnal principal lunar tidal constituent (M3), the largest amplitudes being found in the Paranaguá estuarine system. Therefore, the significance of the local tidal potential was assessed in this study for the most important tidal constituents inside the estuarine system (including M3). The model validation was performed with tidal gauge data, Argo float profiles and satellite measurements of Sea Surface Temperature. The methodology described in this study can be replicated for other important estuarine systems located on the south-eastern Brazilian shelf. Furthermore, the numerical model was developed within a perspective of operational nowcast/forecast simulations, useful for several activities such as navigation and response to emergencies (e.g., oil spills). © 2016, Universidade de Sao Paulo. All rights reserved.


Mateus M.,University of Lisbon | Pinto L.,University of Lisbon | Chambel-Leitao P.,HIDROMOD
Australian Journal of Forensic Sciences | Year: 2015

Ocean circulation models are frequently used in maritime Search and Rescue operations due to their skill in simulating the effects of local currents on the transport of people or objects. They are also occasionally used in forensic contexts. Frequently, positively or neutrally buoyant passive particles are used in these simulations, as a proxy for the objects in the study. In this paper, the adequacy of passive particle model simulations is tested in an attempt to reproduce the drift of a real case situation. The case study consists of a drowning accident in which the drift was ~2 km for a post-mortem submersion interval (PMSI) of 8.6 days. The simulation results highlighted the limitation of the methodology to predict the correct drift. However, we discuss the shortcomings of the modelling approach, and suggest ways to improve the skill of such numerical tools in predicting body drift after drowning accidents. © 2014 Australian Academy of Forensic Sciences.


Franz G.,University of Lisbon | Pinto L.,University of Lisbon | Ascione I.,University of Lisbon | Mateus M.,University of Lisbon | And 3 more authors.
Estuarine, Coastal and Shelf Science | Year: 2014

Cohesive sediment dynamics in estuarine systems is a major issue in water quality and engineering problems. Numerical models can help to assess the complex dynamics of cohesive sediments, integrating the information collected in monitoring studies. Following a numerical approach we investigated the main factors that influence the cohesive sediment dynamics in an estuarine system composed of large mudflats (Tagus estuary, Portugal). After a spin up period of the bottom layer and considering the combined effect of waves and currents on the bottom shear stress, the dynamics of cohesive sediment during the fortnightly and daily erosion-sedimentation cycle was properly reproduced by the model. The results of cohesive suspended sediments were validated with data from sixteen monitoring stations located along the estuary and turbidity data measured by two multiparametric probes. The hydrodynamics were previously validated by harmonic analysis and with ADCP data. Although tidal currents are the major cause of cohesive sediment erosion, the results suggest that wind waves also play an important role. The simulated sediment mass involved in the fortnightly tidal cycle was in the same order of magnitude of the annual load from the rivers, as observed in previous studies based on field data. © 2014 Elsevier Ltd.


Leitao P.,HIDROMOD | Galvao P.,HIDROMOD | Aires E.,HIDROMOD | Almeida L.,HIDROMOD | Viegas C.,University of Lisbon
Environmental Engineering and Management Journal | Year: 2012

In the framework of the Lenvis project, a web service infrastructure able to provide professional users with field data and model results in real time was developed. One of the web services developed (web service model) executes a particle tracking model to simulate the dispersion of sewage discharges. This web service is comprised of a web client with multiple features. The client allows users to explore hydrodynamic forecast results in a GIS environment and define sewer discharges. The web client using the web service model simulates (1 day simulation takes less than 5 minutes to run) the impact over the water quality. The tool was tested for the Estoril coastal area (Lisbon - Portugal), specifically for the Carcavelos, Torre and Oeiras beaches.


Ribeiro J.,HIDROMOD | Silva A.,HIDROMOD | Leitao P.,HIDROMOD
Natural Hazards and Earth System Science | Year: 2011

The use of high resolution hydrodynamic modelling to simulate the potential effects of tsunami events can provide relevant information about the most probable inundation areas. Moreover, the consideration of complementary data such as the type of buildings, location of priority equipment, type of roads, enables mapping of the most vulnerable zones, computing of the expected damage on man-made structures, constrain of the definition of rescue areas and escape routes, adaptation of emergency plans and proper evaluation of the vulnerability associated with different areas and/or equipment. Such an approach was used to evaluate the specific risks associated with a potential occurrence of a tsunami event in the region of Setúbal (Portugal), which was one of the areas most seriously affected by the 1755 tsunami. In order to perform an evaluation of the hazard associated with the occurrence of a similar event, high resolution wave propagation simulations were performed considering different potential earthquake sources with different magnitudes. Based on these simulations, detailed inundation maps associated with the different events were produced. These results were combined with the available information on the vulnerability of the local infrastructures (building types, roads and streets characteristics, priority buildings) in order to impose restrictions in the production of high-scale potential damage maps, escape routes and emergency routes maps. © 2011 Author(s).


Otero-Diaz L.,Universidad del Norte, Colombia | Pierini J.O.,National University of Costa Rica | Chambel-Leitao P.,HIDROMOD | Malhadas M.,HIDROMOD | And 3 more authors.
DYNA (Colombia) | Year: 2014

The simulated droplet trajectories of the 3-D model at the Caribbean platform showed that droplets with a diameter of 50μmformed a distinct subsurface plume, which was transported horizontally and could remain below the surface. This plume could have a very restricted area of impact because the dispersion is only controlled by the ocean currents which, at 1000 m depth, have a low intensity and are quite turbulent. In this case, the formed plume stayed trapped at 1000 m depth, not posing a risk to the Caribbean Coast. In contrast, droplets with diameters of 250 μm, 1 and 10mm rose rapidly to the surface, even with different velocities (6, 10, 20 ms-1). © The authors; licensee Universidad Nacional de Colombia.

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