Application of geographical information systems on Portuguese coastal projects

The Portuguese northwest coastal zone is included in one of the most critical European coastal zones and presents serious coastal problems in almost all its extension. Various incidents have ocurred in this area, such as coastal erosion, flooding, destruction of infrastructures and sea defences, dune ruptures, and overtopping. High urban, economic and tourist pressures also occur in this area Erosion problems and the coastline retreat are related to the reduction of the sources of sedimentary deposition, generally as a consequence of total or partial regularization of rivers, construction of harbour breakwaters, and dredging works. It is important to have monitoring procedures to observe the coastline evolution that could be a quantifiable qualitative indicator of the vulnerability and risk of those coastal areas, especially in some areas where it is necessary to build defence structures to protect coastal settlements. In this context the Geographic Information Systems (GIS) play an important role, as they permit the integration, storing, manipulation and analysis of different kinds and formats of data. In this paper four GIS applications will be presented. They were carried out on the Portuguese west coast and related to the design of coastal defence structures and to the evolution of the coastline.