Hierarchical cluster analysis (HCA)
A Q-mode HCA was performed in the study area to understand the chemical composition of groundwater. It is the most efficient tool for data classification and useful graphical methods to identifying the source of contamination in groundwater (MarĂ­n Celestino et al., 2018). HCA analysis was carried out in the study area based on the water quality parameters and sample stations. Also, the Wards linkage method with a square Euclidean distance classification method for comparison measurement is used to produces the most distinctive groups in the dendrogram (Prajapati et al., 2020). The result of HCA in the study area, cluster 1, comprises CO32-, F-, pH, K+, Na+, NO3-, Mg2+, SO42-, Ca2+, HCO3-, and Cl- are jointly associated with together. Cluster 2 shows that TH associated with cluster 1, and it indicates geogenic source, weathering of calcite and dolomite rocks, and anthropogenic activities. Cluster 3 represents the EC and TDS associated with clusters 1 and 2 (Fig.17a). It shows that the reverse ion exchange process is highly influencing the nature of groundwater in the study area (Table.9a). In addition, HCA was performed based on the sample location and shown in fig. 16b. It shows that, three different types of groups are group1 comprises sample locations 1,3,17,18 and 20, group 2 represents 4,5,7,10,14,22,24 and 27 and group 3 comprises 2,6,8,9,11,12,13,15, 16,19,21,23,25,26,28,29 and 30 (Table.9b). A partial number of sample locations are having the same characteristic of groundwater and less contamination (Fig.17b). The results of the HCA variable and sample locations are reveals that geogenic and reverse ion exchange and anthropogenic activities such as waste disposal, sewage intrusion and excess utilization of synthetic fertilizers are high influencing the nature of groundwater.