Alberto Azevedo

A cross-scale numerical modeling system for management support of oil spill accidents

A flexible 2D/3D oil spill modeling system addressing the distinct nature of the surface and water column fluids, major oil weathering and improved retention/reposition processes in coastal zones is presented. The system integrates hydrodynamic, transport and oil weathering modules, which can be combined to offer different-complexity descriptions as required by applications across the river-to-ocean continuum. Features include accounting for different composition and reology in the surface and water column mixtures, as well as spreading, evaporation, water-in-oil emulsification, shoreline retention, dispersion and dissolution. The use of unstructured grids provides flexibility and efficiency in handling spills in complex geometries and across scales. The use of high-order Eulerian-Lagrangian methods allows for computational efficiency and for handling key processes in ways consistent with their distinct mathematical nature and time scales. The modeling system is tested through a suite of synthetic, laboratory and realistic-domain benchmarks, which demonstrate robust handling of key processes and of 2D/3D couplings. The application of the modeling system to a spill scenario at the entrance of a port in a coastal lagoon illustrates the power of the approach to represent spills that occur in coastal regions with complex boundaries and bathymetry.

An interactive WebGIS observatory platform for enhanced support of integrated coastal management

ABSTRACT Oliveira, A., Jesus, G., Gomes, J.L., Rogeiro, J., Azevedo, A., Rodrigues, M., Fortunato, A.B., Dias, J.M., Tomas, L.M., Oliveira, E.R. Alves, F.L., den Boer, S., 2014. An interactive WebGIS observatory platform for enhanced support of coastal management. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 507–512, ISSN 0749-0208. A new WebGIS observatory platform is presented, tailored for risk assessment and emergency preparation and response in coastal areas. The tool combines a sophisticated forecast modeling system for multi-scale analysis of water bodies, including waves, hydrodynamics and oil spills prediction, with real-time monitoring networks for forcing and continuous validation purposes. Tailor-made visualization and analysis products, conceptualized for multiple uses through a service-oriented framework, provide an easy and interactive access to both data and predictions. The system was customized for oil spills risk assessment and the rapid response to an oil spill emergency, and applied to the Aveiro lagoon. The tool addresses oil spill problems in two complementary ways: 1) a detailed risk assessment through georeferenced hazard and vulnerability maps and GIS layers of information to support the definition of contingency plans; and 2) the visualization of georeferenced oil spill predictions produced by a real-time oil spill forecasting system. Improvements relative to existing risk systems are 1) the possibility of selecting quick-access predictions for fast emergency response or high-quality, georeferenced GIS prediction products, 2) the flexibility in accessing products to evaluate local impacts of oil spills both in the water column and in the intertidal areas, and 3) the enhanced hazard and risk analysis through a combination of a multi-scenarios approach with the historical database of spill predictions, forced by daily hydrodynamic forecasts. Dependability of information, for both model results and monitoring data, is being implemented through innovative ways, targeting the robustness and quality control of the WebGIS platform.

Development of an oil spill hazard scenarios database for risk assessment

ABSTRACT den Boer, S., Azevedo, A., Vaz, L., Costa, R., Fortunato, A.B., Oliveira, A., Tomás, L.M., Dias, J.M., Rodrigues, M., 2014. Development of an oil spill hazard scenarios database for risk assessment. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 539–544, ISSN 0749-0208. The occurrence of oil spills in coastal regions may have catastrophic consequences on the environment and severe socio-economic impacts. This work presents a new methodology to evaluate the risk associated with oil spills in coastal zones and estuaries, and illustrates its application in a coastal lagoon (Ria de Aveiro, Portugal). A ranked list of the hydrodynamic scenarios under which oil spills are most likely generated through the analysis of 33 years of wave and wind data, retrieved from the ERA-INTERIM project database, and from the analysis of oil spills that occurred in the Atlantic Iberian shelf. Considering six spill locations and a single oil type spill inside the Aveiro harbor, the database resulted in approximately 3500 simulations. Hydrodynamic simulations were made with the MORSYS2D modeling system, a soft coupling of the hydrodynamic model ELCIRC and the wave model SWAN. The high-accuracy, unstructured grid, oil fate model VOILS was used in 2D mode to simulate the transport and the oil weathering processes at the surface and in the intertidal areas. The hazard assessment analysis included the determination of the trajectory of the plumes, the shoreline retention areas affected by the oil and their oil exposure time. Time evolution of the oil properties, such as the oil evaporation rate and emulsification processes of the mixture, are provided to support clean-up operations, as well as robustness controls such as oil mass balance.

Operational forecast framework applied to extreme sea levels at regional and local scales

ABSTRACT The design, implementation and demonstration of a novel and generic computational forecast framework for multi-scale prediction of extreme sea levels and associated flooding is presented. Denoted Water Information Forecast Framework (WIFF), it integrates process-based models for waves, tides and surges from regional to local scales, predicting the flooding of coastal areas, and supporting the routine and emergency management of coastal resources. WIFF manages the simulations and the real-time monitoring data, archives the data and makes the information available through a WebGIS that targets users with distinct access privileges. Additionally, the web component of WIFF adapts automatically and transparently to any device. WIFF also provides ways to assess the model accuracy and generates tailored products based on model results and observations. WIFF is demonstrated in the prediction of extreme water levels in the Portuguese coast, simulating processes at different scales: at basin scales, waves are simulated in the North Atlantic and in the Portuguese shelf, and sea levels due to tides and atmospheric forcings are simulated in the Northeast Atlantic; at estuarine scales, high-resolution, fully coupled wave/circulation predictions are performed in the Tagus estuary to account for wave–current interactions. User-oriented georeferenced products are generated, including automatic model/data comparisons, targeting the needs of civil protection agents and combining for the first time an agile, service-oriented platform with high-resolution, process-rich predictions of the Tagus dynamics.

Experimental and numerical study of the hydrodynamics of the western sector of Ria Formosa

ABSTRACT Jacob, J., Cardeira, S., Rodrigues, M., Bruneau, N., Azevedo, A., Fortunato, A.B., Rosa, M. and Cravo, A., 2013. Experimental and numerical study of the hydrodynamics of the western sector of Ria Formosa. The western sector of Ria Formosa, a lagoon system in the south of Portugal, represents approximately 90% of the total tidal prism of the lagoon and includes three inlets. Two sets of field campaigns to characterize the hydrodynamics of this sector in neap and spring tide conditions were conducted in the autumn of 2011 and spring 2012. The main findings related to the inlets hydrodynamics and water exchanges between the lagoon and the ocean along semi-diurnal tidal cycles are presented. To estimate the relative contribution of the three inlets to the water exchanges between Ria Formosa and the ocean, discharges were evaluated hourly along complete neap and spring semi-diurnal tidal cycles and the tidal prisms computed. In addition, two sea level time series measured in Faro-Olhão inlet and Faro commercial pier were harmonically analyzed. The results were compared with previous studies and used to validate the ELCIRC hydrodynamic model. This model provided additional information about the circulation and tidal prisms and distortion inside the western Ria Formosa. This study confirmed the Faro-Olhão inlet as the main inlet in terms of contribution for the total tidal prism. It is shown that the Ancão inlet lost hydraulic efficiency, contributing less than 6% to the total tidal prism in all situations and the Armona inlet gained efficiency in spring tide and lost efficiency in neap tide. Moreover, the Faro-Olhão inlet exhibits flood prisms higher than ebb prisms under neap and spring tides, suggesting a residual circulation towards the Ancão and Armona inlets.

Salinity modelling accuracy of a coastal lagoon: a comparative river flow analysis of basin model vs. traditional approaches

ABSTRACT Tomas, L.M., Rodrigues, M, Fortunato, A.B., Azevedo, A, Leitão, P.C., Oliveira, A., Rocha, A., Lopes, J.F., Dias, J.M., 2014. Salinity modelling accuracy of a coastal lagoon: a comparative river flow analysis of basin model vs. traditional approaches. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 586–591, ISSN 0749-0208.. The main purpose of this study is to investigate the uncertainties in the modelling of salinity fields in the Ria de Aveiro lagoon associated with the estimation of river flow discharges. The prediction of fresh water inputs is necessary to properly implement forcing conditions and consequently to provide accurate forecasts of baroclinic circulation in coastal lagoons. Located in the north-western Portuguese coast, the Ria de Aveiro is a shallow vertically homogeneous mesotidal coastal lagoon with a complex geometry. Although it is tidally dominated, it receives freshwater from five rivers, the Vouga, Antuã, Cáster, Boco and Ribeira dos Moínhos, whose contributions are responsible for the salinity variation within the system. This research concerns the accurate prediction of river flow to be used in the operational forecast system of the lagoon. Given the lack of observed data for river discharges, as there are only two real time measuring stations located in the Vouga and Antuã river basins, but far from the lagoon, alternative estimation approaches are needed. In order to estimate the river discharges for all five rivers, two different approaches were considered: the first estimates the Vouga river flow, the major fresh water source, based on the nearest real time measuring station and estimates the other river flows based on river basin areas proportionality; the second establishes river flows based on the precipitation/river flow relationships for the Vouga and Antuã rivers and on the areas of the other river basins using the SWAT model. The methodology comprises the exploitation of the 3D unstructured-grid hydrodynamic model SELFE, required to adequately simulate the flow and transport of salt in very complex domains such as the Ria de Aveiro. The model is forced by water elevations at the ocean boundary and river flows at the river boundaries, and atmospheric drivers at the surface (wind stress, atmospheric pressure and heat fluxes). The salinity model predictions were compared with data from seven stations, and its accuracy was assessed through Root Mean Square Error (RMSE). The river flows estimated by the first method led to the best fit between observed and predicted salinity.

Managing a Coastal Sensors Network in a Nowcast-Forecast Information System

This paper presents a study on the integration of heterogeneous sensor nodes into a wireless sensor network and its use in providing real-time information about water conditions, contributing to water resources management. The work focuses on presenting the methodology used to automatically communicate, parse and store the sensor network data and its application to a real case study. The development of a new platform for efficient management and analysis of the gathered data and its use for automatic assertion of real-time model forecasts quality against stored data is also presented. On-going work on the development of a mobile application for real-time data access in mobile devices is also anticipated.

Running high resolution coastal models in forecast systems: moving from workstations and hpc cluster to cloud resources

Abstract Computational forecast systems (CFS) are essential modelling tools for coastal management by providing water dynamics predictions. Nowadays CFS are processed in dedicated workstations, fulfilling quality control through automatic comparison with field data. Recently, CFS has been successfully ported to High Performance Computing (HPC) resources, maintained by highly-specialized staff in these complex environments. The need to increase the available resources for more demanding applications and to enhance the portability for use in non-scientific institutions has promoted the search for more flexible and user-friendly approaches. The scalability and flexibility of cloud resources, with dedicated services for facilitating their use, makes them an attractive option. Herein, the performance of CFS using ECO-SELFE MPI-based model is assessed and compared for the first time in multiple environments, including local workstations, an HPC cluster and a pilot cloud. The analysis is conducted in a range of resources from the physical core count available at the smaller resources to the optimal number of processes, using cloud and HPC cluster resources. Results for the smaller, common physical resources show that the cloud is an attractive option for CFS operation. As the optimal number of processes for the use case is at the limit of the workstations common pool, an analysis was also performed using HPC cluster nodes and federated MPI resources. Results show that the cloud remains an attractive option for CFS. This conclusion is valid both for the use of a single host or through federated hosts, providing that efficient communication infrastructure (such as SRIOV) is available.

Improving sensor-fusion with environmental models

This paper presents an algorithm to improve sensor fusion results in outdoor WSNs using environmental models to redefine periodically which sensors to use and the amount of weight for each particular sensor in the fusion solution. Using daily forecast simulations of the monitored environment dynamics, clusters of sensor nodes sharing data correlation can be defined, for priority sensor selection in a fusion algorithm. The strategy was validated in an operational aquatic sensor network comprised of several sensors scattered over a multiple square kilometers area. It allowed the use of geographically separated nodes with confidence and sometimes even in alternative of closer nodes, unlike most fusion approaches that use quasi-redundant information provided by nearby sensor nodes. This approach represents a major step in the creation of a framework to assess the validity of the monitoring data in WSNs.