Finding the proper methodology for geodiversity assessment : a recent approach in Brazil and Portugal

Abstract

A methodology for the quantitative assessment of geodiversity was defined and tested at various scales. It was applied to the Xingu River Basin, Amazon, Brazil (about 510,000 km2), Paraná state, Brazil (about 200,000 km2), and Portugal mainland (about 89,000 km2). This method is intended to assess all geodiversity components and to avoid overrating any particular component, such as lithology or relief, a common weakness of other methods. The method is based on the overlay of a grid over different maps at scales that range according to the areas under analysis, with the final Geodiversity Index being the sum of five partial indexes calculated on the grid. Partial indexes were calculated using GIS software by counting all the occurrences present in the selected maps for each grid square. The Geodiversity Index can take the form of a GIS automatically generated isoline map, allowing an easy interpretation by those without or with little geological background. The map can be used as a tool in land-use planning, particularly in identifying priority areas for conservation, management and use of natural resources.