Urban settlements delimitation in low-density areas—An application to the municipality of Tomar (Portugal)

One of the major issues in land-use planning is how to contain urban sprawl. To this effect, plans integrate new regulations and mechanisms that severely limit construction outside urban perimeters and restrict the areas available for expansion within the settlements. Before enforcing these restrictions, a review and correction of existing delimitation of settlements was necessary. The new limits were established through the identification of effectively consolidated urban areas. In the absence of official criteria defining them, this paper presents a methodology establishing the limits of these consolidated areas. Based on the identification, in a Geographical Information System (GIS) of existing buildings, and incorporating the analysis of road network, social facilities, and physiographic constraints (such as floodplains or steep slopes), several criteria were defined so as to delimit the urban settlements. A review of other methodologies is presented as a contextualization of the proposed one, but it is not the focus of the paper to specifically contrast or appreciate them. The study area is the municipality of Tomar, in Central Portugal, a territory with very disperse human occupation. Having achieved an accurate delimitation of the settlements’ current extent that reflects the purposes of rational land-use, the settlement delimitation was successfully revised so as to mirror the current occupation. Also, the objectivity and clarity of the adopted criteria, and its applicability to the whole municipality, allowed the methodology to be unanimously well received by the Municipal Government and Parish Councils, even if it deals with a somewhat politically delicate subject.