Principal component analysis (PCA)
SPSS 21.0 version was used to carry out the principle component analysis
of groundwater in the study area. The result of PCA shows that more
significant water quality parameters to deteriorate the natural
characteristics of groundwater. The varimax method was adopted to rotate
the parameters in PCA and extraction limitation of the eigen value
greater than one (Pande et al., 2019, Paul et al., 2019). In the study
region, PCA illustrates four factors responsible for the data structure
(Fig.16a and Table.8), with 76.635 % of cumulative variance. Factor 1
comprises of 49.902% of total variance with high loadings for EC, TDS,
TH, Ca2+, Mg2+,
SO42- and
NO3- (Fig.16b). It represents the
anthropogenic activities such as disposal of waste from residents,
sewage intrusion; chemical synthetic fertilizers used for high crop
yield are the major reason for the excess concentration of salt and
other ions.
Factor 2 responsible for 9.618% of total variance with high factor
loadings for pH, HCO3-, weak positive
loadings of EC, TDS, Na+, Mg2+, and
SO42-. It shows that the high value of
hydrogen ions is due to weathering of parent rock, rock water
interaction, and ion exchange process. These are highly influencing
factor in the degradation of groundwater quality. Factor 3 comprises a
total variance of 8.739% with high factor loadings of
K+, CO32- and weak
positive loading of HCO3-. It
indicates that potassium-rich minerals such as feldspars, calcite, and
dolomite weathering are the major reasons. In specifically, farmers are
used 15.5% of nitrogen, and 18.8% of calcium content and easily
water-soluble fertilizers are widely used in the study area. The impact
of these kinds of fertilizers are initially enhanced the growth of the
plant in two to three weeks and gets dissolved into water, finally
leachates are diluted with the groundwater. In Factor 4, total variance
is 8.376% with high loadings factor of sodium and chloride ions. Due to
the action of the ion exchange process, rock water interaction and
anthropogenic activities are highly affecting the quality of groundwater
in the study region (Fig.16c).