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Authors
Abstract(s)
The 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.
Description
Dissertação de mest., Geomática (Análise de Sistemas Ambientais), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2013