Soil Quality and Peri-Urban Expansion of Cities. A Mediterranean Experience (Athens, Greece)

Soil loss and peri-urban settlement expansion are key issues in urban sustainability, with multi-disciplinary implications that go beyond individual ecological and socioeconomic dimensions. Our study illustrates an assessment framework diachronically evaluating urbanization-driven soil quality loss in a Southern European metropolitan region (Athens, Greece). We tested the assumption that urban growth is a process consuming high-quality soils in a selective way analyzing two spatial layers, a map illustrating the diachronic expansion of settlements at five time points (1948, 1975, 1990, 2000, and 2018), and a geo-database reporting basic soil properties. The empirical results showed that the urban expansion in the Athens region took place by consuming higher- quality soil in fertile, mostly flat, districts. It entailed a persistent soil quality decrease over time. This trend globally accelerated in recent years, but in a heterogeneous way. Actually, newly built, more compact areas expanded on soils with lower erosion risk than in the past. Besides, low-density land take is likely to be observed in soils with moderate-high or veryhigh qualities. These evidences reflect the need for a comprehensive evaluation of complex processes of land take informing spatial planning for metropolitan sustainability.