Designing Improved Sediment Transport Visualizations

Monitoring, or more commonly, modeling of sediment transport in the coastal environment is a critical task with relevance to coastline stability, beach erosion, tracking environmental contaminants, and safety of navigation. Increased intensity and regularity of storms such as Superstorm Sandy heighten the importance of our understanding of sediment transport processes. A weakness of current modeling capabilities is the ability to easily visualize the result in an intuitive manner. Many of the available visualization software packages display only a single variable at once, usually as a two-dimensional, plan-view cross-section. With such limited display capabilities, sophisticated 3D models are undermined in both the interpretation of results and dissemination of information to the public. Here we explore a subset of existing modeling capabilities (specifically, modeling scour around man-made structures) and visualization solutions, examine their shortcomings and present a design for a 4D visualization for sediment transport studies that is based on perceptually-focused data visualization research and recent and ongoing developments in multivariate displays. Vector and scalar fields are co-displayed, yet kept independently identifiable utilizing human perception\u27s separation of color, texture, and motion. Bathymetry, sediment grain-size distribution, and forcing hydrodynamics are a subset of the variables investigated for simultaneous representation. Direct interaction with field data is tested to support rapid validation of sediment transport model results. Our goal is a tight integration of both simulated data and real world observations to support analysis and simulation of the impact of major sediment transport events such as hurricanes. We unite modeled results and field observations within a geodatabase designed as an application schema of the Arc Marine Data Model. Our real-world focus is on the Redbird Artificial Reef Site, roughly 18 nautical miles offshor- Delaware Bay, Delaware, where repeated surveys have identified active scour and bedform migration in 27 m water depth amongst the more than 900 deliberately sunken subway cars and vessels. Coincidently collected high-resolution multibeam bathymetry, backscatter, and side-scan sonar data from surface and autonomous underwater vehicle (AUV) systems along with complementary sub-bottom, grab sample, bottom imagery, and wave and current (via ADCP) datasets provide the basis for analysis. This site is particularly attractive due to overlap with the Delaware Bay Operational Forecast System (DBOFS), a model that provides historical and forecast oceanographic data that can be tested in hindcast against significant changes observed at the site during Superstorm Sandy and in predicting future changes through small-scale modeling around the individual reef objects

GIS como ferramenta de ajuda pré- e pós-processamento de modelos hidrodinâmicos. Aplicação ao estuário do Guadiana

Dissertação de mest., Geomática (Análise de Sistemas Ambientais), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2013The main objective of this work is to develop GIS based techniques to aid the setup of hydrodynamic models and to improve model results. This dissertation analyzes well-known GIS methods and proposes new ones to prepare and process estuarine model data. Estuarine hydrodynamic models require management of large quantities of georeferenced information. A Geographic Information System (GIS) can help to store, manage, analyze and display all these data during the input and the output phases. The hydrodynamics of the Guadiana Estuary was simulated using a 2D configuration in MOHID Water Modelling System, based on a boundary fitted curvilinear grid. GIS tools were used to pre-process the model grid and bathymetry. The water domain was extracted from the orthophoto using unsupervised classification of the image based on principal component analysis of the spectral bands. The large amount of bathymetric measurement points was decreased using a spatial regular pattern (hexagons). The missing bathymetry data in some very shallow parts of the estuary were estimated from the orthophoto using correlation between existing data and spectral band values. The bathymetry data were interpolated into curvilinear grids by several different methods, including an advanced method using river straightening (transformation to the along-channel coordinate system). The finite volume model MOHID was used to test these methods and evaluate the associated improvements. The model results were in good agreement with the observations under well-mixed conditions. Including the bathymetry estimated from orthophoto improved the accuracy of the simulations; and using advanced interpolation methods improved the results even more. The bathymetry interpolation in the channel-oriented coordinates significantly improved the direction of the water current. Good quality of the spatial input data was critical for obtaining good model results. The use of GIS tools to produce model inputs proved to be a valuable aid to coastal hydrodynamic modelling increasing substantially the model accuracy. This dissertation is useful in both theoretical and practical fields of science: in theoretical, by analyzing and developing GIS methods to prepare and process estuarine hydrodynamic model data, in practical, by creating an improved model setup for the Guadiana Estuary, using more accurate bathymetric data and a new curvilinear grid, thus obtaining more realistic results

NUMERICAL MODELING OF CIRCULATION, VOLUME FLUXES AND TRACER TRANSPORT IN SINGAPORE COASTAL WATERS

Ph.DDOCTOR OF PHILOSOPH

A GIS pre-processor for pollutant transport modelling

Summarization: A GIS pre-processor was developed to produce bathymetric grids and shorelines for open and closed boundary as input to a three-dimensional hydrodynamic/pollutant transport model to simulate the currents and pollutant transport in lakes and coastal areas. The pre-processor operates within ArcView GIS and can read hydrographic files in different formats. The use of this GIS module facilitates the implementation of different pollutant transport scenarios, which in turn can significantly contribute to the decision-making process concerning one of the most contemporary environmental problems. The applicability of the pre-processor is illustrated through a case study on Suda Bay, located in Crete, Greece.Παρουσιάστηκε στο: Environmental Modelling amd Softwar