The subthermal potential of karstic groundwater of Kuaj-Beljanica region in Serbia estimated by the multivariate analysis

Abstract

To define the potential uses of groundwater, a detailed hydrochemical analysis was carried out in the Kuaj-Beljanica Massif at seven locations, in the eastern part of the Republic of Serbia. The hydrogeochemical analysis led to a better understanding of the hydrogeochemical processes occurring underground, as well as the existence and origin of groundwater heat sources. The chemical composition of the thermal groundwater indicates different formation conditions, the influence of different rock types and different physico-chemical processes with time and temperature variations on water quality. Better insight into the geochemical and thermal conditions of groundwater can identify the most prospective locations for geothermal applications such as indoor and outdoor space heating, sports, recreation and tourism, as well as industrial applications, with or without the additional use of heat pumps. Factor analysis (FA), especially principal component analysis (PCA) and cluster analysis (CA) were applied for the evaluation of the spatial/temporal variations of Kuaj-Beljanica thermal groundwater. It was concluded that PCA was the optimum method for explaining functional relationships between the chemical elements. After data reduction, three main factors controlling variability were identified. Hierarchical cluster analysis (HCA) was applied for sample differentiation according to sample location which resulted in the grouping of the examined location into three main groups according to their thermal or geochemical potential: Group I: lowest potential for any purpose; Group II: best thermal potential (wellness centres, agriculture and heating of different facilities and Group III: specific hydrogeochemical potential suitable for bottling or balneal tourism.