GIS Tool for Coastal Engineering

Nuno Charneca, Ana Catarina Zózimo, Juana Fortes

Hydraulics and Environment Department, LNEC (P)

Abstract

In coastal engineering studies, the preparation of bathymetric data and the pre- and post-processing of data and results of numerical models is a task that depends of the modeler's experience and the degree of complexity of both the case study and the numerical model involved.
LNEC has several bathymetric surveys of the Portuguese coast (Covas, 1991) and that are needed as input for several different numerical wave models, used in that institution. One of the models frequently used in LNEC is the regular wave model REFDIF (Dalrymple and Kirby, 1991).
In order to automate all the pre- and post-processing procedures of the numerical models, arose in LNEC the idea of developing an application that would integrate a Geographical Information System (GIS) and the numerical models. In the meanwhile, this initial idea was further expanded to the development of a personalized GIS application for studies of coastal engineering, that would have both the GIS and the numerical models capabilities, and that should also have tools to help decision makings.
This application, implemented at the GIS level, enables the direct access of the bathymetric information by the numerical models.
Data storage is guaranteed by an Oracle database, through which the data security and management is assured.
The present work presents the main ideas of this GIS application and describes the tasks that have already been performed. These tasks consisted essentially in exploring the capabilities and limitations of the GIS software available at LNEC, in what concerns the numerical models. To accomplish this objective, the numerical wave model REFDIF was applied to the port of Sines adjacent maritime zone, in the propagation of waves from offshore to the coastline.
The new application in development will result in a considerable gain of time in the pre- and post- processing of data, in a much more friendly way of using this type of numerical models and finally in the gaining of all the other enormous GIS capabilities at several levels.

References:

• Covas, J.M.A. (1981a) - Modelos matemáticos para o estudo da propagação e da deformação das ondas de gravidade. O cálculo automático de diagramas de refracção. Memória n° 551, LNEC, Lisbon (in Portuguese).
• Dalrymple, R. A.; Kirby, J. T. 1991. Documentation manual. Combined refraction-diffraction model. REF/DIF 1 version 2.3, CACR Report Nº 91-2, Center for Applied Coastal Research. Department of Civil Engineering, University of Delaware, January.