Comparison of quantitative and qualitative-quantitative geodiversity assessment-based geosite recognition in the Novohrad-Nógrád UNESCO Global Geopark, Hungary/Slovakia

Abstract

One of the first steps for geopark establishment is the recognition of geoscientific locations of interest (geosites), their description and geoconservation design. Such works can scientifically recognize their uniqueness in both regional and global scales. However, the description often requires direct identification and observation of the main sites of geoscientific relevance, which is a time-consuming, resource intensive and expensive procedure. Hence, the utilization of Geographical Information Systems (GIS) is a practical first order tool for the calculation of geodiversity values for the recognition of geosites to minimize a search area for direct observation and description of the diversity and the geoheritage of a studied region. Quantitative assessment in these days is one of the most popular methodologies developed to identify geodiversity hotspots of area of interests in various of spatial scales. This type of approach uses indices for defining the diversity of geoscientific variables (however the applied spatial variables can vary from method to method) over the unit-sized regions of the sample area. Hence, quantitative assessment depends on the availability, accuracy, and scale of data. In this research, we used geological, pedological, geomorphological, and hydrological data that were processed within QGIS. The geodiversity index is produced by summing the normalized variety of thematic features (thematic cell value divided by the maximum cell value of that thematic variable) over a spatial unit (geology, pedology, geomorphology) and with an additional expression of the hydrological variables. By using normalization, the overrepresentation of subindices is eliminated. Rooting from this, qualitative-quantitative methodology was created to enhance the recognition of potential geosites (hotspots) utilizing less data, a case common in remote or understudied and/or large areas geological mapping is not performed beyond 1 to 50,000 scale. The qualitative part of methodology is an evaluation system specifically tailored for each element of geodiversity included into assessment, where their (elements) number demonstrate the quantitative part of equation. Currently, the methodology utilizes three elements of geodiversity: geology, geomorphology, and hydrology calculated in QGIS software, while only geological map required for assessment. Each element has been described to emphasize features required for geosite recognition, which are rock type rareness, slope angle, and Strahler stream order for mentioned elements respectively. The result demonstrates the hotspots areas of potential geosites located in the studied region. Both methodologies have been used for the region of Novohrad-Nógrád UNESCO Global Geopark to recognize potential geosites. Methodologies have been represented with the same 2.5*2.5 km grid size evaluated to a 5-point system to recognize their differences. Additionally, both models have been compared with the main geosite locations within an active and operating Novohrad-Nógrád UNESCO Global Geopark. The result of the project demonstrates that the similarity between the two methodologies is only 30 %, and similar areas mostly located in the “low” value areas. Moreover, quantitative methodology catching 42 already known geosites, while qualitative-quantitative recognizing 31 (for areas with high and the highest value).