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Fig. 1.
Geographic location, hydrogeological conditions, distribution of water sampling points and profiles of the study area.
Fig. 2.
Methodological framework of this study.
Fig. 3.
Violin plot of chemical composition of groundwater samples.
Fig. 4.
(a) Groundwater Piper map for 2012; (b) Groundwater Piper map for 2020.
Fig. 5.
(a) and (b) Gibbs plots, (c) Ca
2
+- Mg
2
+ion ratio plots, (d) Na+- Cl−ion ratio plots, and (e) (Ca
2
++
Mg
2
+) - (HCO3
−+
SO
4 2
−)-(Na++
K+)-Cl
-
ion ratio plots.
Fig. 6.
Results of PCA analyses over the years 2011
–
2015.
Fig. 7.
Characteristics of spatial distribution of calcium ion activity and saturation index in the study (a)2011, (b)2015 and (c)2020.
Fig. 8.
The extent map of anthropogenic impacts on the groundwater environment
Fig. 9.
The analysis of groundwater chemical kinetic constants from 2011 to 2020 is conducted, considering the spatial and temporal variations, in conjunction with maps illustrating precipitation patterns and changes in farmland area. Areas with large interannual variations in groundwater chemical kinetic constants are circled by black dashed lines, indicating strong anthropogenic impacts.
Fig. 10.
(a) Land use type; (b) Groundwater depth; (c) Population density; (d) Lithological thickness of the vadose zone.
Fig. 11.
(a) Statistical box plots depicting the distribution of nitrogen and oxygen isotopes. (b) Mapping of sources of nitrate pollution in groundwater.
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