GIS modelling for urban growth in a vineyard region

Areas of urban sprawl can present difficulties for land use monitoring as these territories are a mixture of rural areas with several urban compounds generally spread along major road axis. The complexity of the analysis is further enhanced if the built area is mingled with vineyards as these can be difficult to distinguish from building roofs in hilly areas in certain periods of the year when they have the same reflectance. This paper is set to achieve three objectives: i) to present the results obtained in the Douro Valley that are still a land-mark in the Northern Region of Portugal; ii) to describe further developments of GIS for the Douro Region; iii) to discuss future practical applications. The analysis of urban sprawl evolution needed the use of aerial photographs in the urban fringe to validate the data extracted from the LANDSAT image used for the first time, in 1989, in the Douro Region for an area of 700 Km(2) (842 rows * 1343 columns). Other analysis were performed for the production of thematic maps according to the Regional Land-Use Plan for the Douro Valley at scale 1/25 000 and using the draft maps of the CORINE Programme at 1/100 000. Later on, other projects and programmes for the catchment area of Douro River (the biggest in the Iberian Peninsula) made it possible to have a GIS system at scale 1/250 000 covering the whole territory from the mouth in Oporto to the mountain of Urbion. in Spain, where the river starts. The overall conclusion on the analysis carried out for this area is that it started as being difficult to establish the "adequate" boundary of the urban areas in sub-regions with urban sprawl and heterogeneous mosaic occupation. Nevertheless, combining aerial photographs, old inventories and local knowledge, the work performed at that early beginning provided the ground and planted the seeds for further research and field applications.