Geomorphodiversity and anthropization indices for Italian urban areas

Abstract

Urban geomorphology analyzes modifications of morphology and topography induced by human activity in cities, urban and peri–urban areas. Urban expansion modifies ecosystems, but global actions for sustainability focus on the biosphere, overlooking the role of abiotic components, embedded in and supported by the geosphere and its ecosystem services.

We propose the joint study of indicators of land surface variability and of anthropic modifications. We consider geomorphodiversity, as a discrete measure of richness and variability of abiotic components, and a new index describing the degree of human impact inferred from land cover classes. We suggest that a joint study of the two indicators helps quantifying and understanding the effect of specific land cover changes on areas with different values of geomorphodiversity and the relationships between abiotic parameters and the human presence in urban areas.

Public datasets permits study geomorphology simultaneously at the national scale, and the local scale, within individual urban areas. We show that (1) urban development in Italy was fostered in lowlands, alluvial plains or hills, and urban areas with large values of geomorphodiversity host larger numbers of natural areas; (2) different definitions of urban boundaries are essential to investigate different aspects of human impact on the landscape; (3) synthetic scenarios of land use change, corresponding to different values of anthropization, are useful to study the effect on geomorphodiversity.

Quantitative geomorphodiversity and anthropization index contain complementary information, and their joint study is an additional tool to plan city development and conservation of natural areas in a broad sense.