Quantitative assessment of geodiversity and urban growth impacts in Armação dos Búzios, Rio de Janeiro, Brazil

•A methodological review is presented with important issues that need discussion in quantitative mappings of geodiversity.•A Geodiversity Index Map is created considering some of the most important existing proposals so far.•The Geodiversity Map was integrated to an Urban Growth Map, which is an innovative approach to assess geodiversity losses.

The concept of geodiversity, which refers to the diversity of abiotic elements of nature, is passing through a period of methodological development. The concept has a great potential of becoming an efficient territorial management tool as the physical environment is the basis in which biodiversity and human societies develop. However, this potential has not yet been achieved because the methodologies of practical application are not consistent enough. This work aimed to contribute to this issue by applying a method of quantitative mapping of geodiversity at a landscape scale and integrating it to an urban growth map in Armação dos Búzios municipality, located in Rio de Janeiro State, Brazil. On the basis of some of the most important previous proposals, a Geodiversity Index Map of Armação dos Búzios was created, which shows the richness and distribution of the elements of geodiversity (geology, geomorphology, soils, and hydrology) throughout the territory. With this product, it was possible to identify the most geodiverse areas of the municipality. After that, an Urban Growth Map of Armação dos Búzios was created by the photointerpretation of aerial photographs from 1976 to 2006, in which the urban areas in both dates were mapped, allowing the observation of how much the urban area grew during this time. By integrating these two maps, we were able to quantify the impacted areas in relation to the geodiversity. The results showed that urbanization impacted a significant portion of the areas classified with high and very high geodiversity indices, highlighting that the physical environment, and consequently the biodiversity, are under serious threat, and it must be taken into account in public policies and territorial management. In addition, this work aimed to contribute to the methodological development of the concept of geodiversity, which still needs more tests and discussions to be improved and widely applied, especially in nature conservation issues.