Searching for limits to urban sprawl: methodology for the delimitation of urban areas in Spanish medium-sized cities

A methodology is proposed for the delimitation of urban areas articulated by medium-sized cities in Spain. With the time reference 2000-2020, we work on a set of thirty-four interior medium-sized cities. The starting criterion is accessibility, taking the reference of the twenty-minute isochron. Based on the analysis of six indicators -variation rate of urbanized land, housing, and population, youth index, active agricultural population and service population- the Urban Transformation Index (ITU) is generated, supported by the use of multi-criteria techniques and analytical cartography. Typologies of urban areas are established according to the transformation dynamics observed (high, medium and low) and, in each area, the scope, intensity and gradation of urban sprawl processes are identified.