Spatial distribution of groundwater quality parameters in the Velika Morava River Basin, central Serbia

The reported study includes analysis of 14 physico-chemical parameters of alluvial groundwater based on data collected from 26 piezometers in the Velika Morava River Basin from 2004 to 2014. Eleven of the parameters were assessed applying hierarchical cluster analysis and principal component analysis to examine the spatial distribution, identify the main processes in groundwater variations and segregate the dominant sampling sites based on the characteristic parameters. A Piper diagram shows that the studied alluvial groundwaters are predominantly of the Ca–HCO type (67.3%) and to a lesser extent of the mixed Ca–Mg–HCO type (21.6%). Hierarchical clustering results in four clusters depending on the similarities of the hydrochemical parameters. Principal component analysis explains 65.4% of total variance with PC1 (32.5% variance), PC2 (19.8% variance) and PC3 (13.1% variance). A comparative analysis reveals that the main processes responsible for the hydrochemical composition of groundwater in the Velika Morava alluvion are carbonate dissolution-anthropogenic pressure, feldspar weathering and migration caused by river–aquifer interaction. Considerable loading of the alluvial groundwater caused by a complex geologic framework, natural factors and human activities in the river basin contributed to the segregation of six dominant sampling sites. The obtained results can be very useful in the development of an optimal spatial plan for groundwater monitoring, focusing on increasing the density of the national monitoring network and frequency of assessing alluvial groundwater on the dominant sampling sites (from annual to seasonal).