## 3 Results and Discussion
### Hydrochemical Characteristics  
Hydrochemical analysis was carried out to characterize the Cuernavaca aquifer's groundwater. A high content of salts in groundwater could lead to the salinization of the soils and crop yield losses due to dehydration of plants [38; 42]. The concentrations of salts in the Cuernavaca aquifer showed the following behavior:  
\[\text{HCO}_{3}{}^{-}>\text{Ca}^{2+}>\text{Na}^{+}>\text{Mg}^{2+}>\text{Cl}^{-}> \text{SO}_{4}{}^{2-}>\text{K}^{+}>\text{NO}_{3}{}^{-}\]  
Figure 11a shows the Piper triangular diagram. In this figure, the mean values of 34 samples at each sampling point were used. This diagram is a graphical representation of groundwater chemistry, where the relative concentrations of cations and anions are shown by separate ternary plots. In the lower-left ternary plot (cation diagram), a dominance of \(\text{Mg}^{2+}\) and \(\text{Na}^{+}+\text{K}^{+}\) is observed. This dominance could be related to progressive evaporation and ion exchange processes [43]. The lower-right ternary plot (anion diagram) indicated that the groundwater chemistry of the Cuernavaca aquifer is highly influenced by Calcium-bicarbonate type and Bicarbonate type [44]. These results are consistent with the results suggested by other researchers [45]. Figure 11b shows the Schoeller diagram which exhibits a similar behavior of cations and anions in the multiple samples from different wells. This diagram demonstrated that the highest equivalent concentrations of the ions were present in sampling site P2, where \(\text{Ca}^{2+}\) and \(\text{HCO}_{3}{}^{-}\) showed the highest equivalent concentrations of cations and anions, respectively. Similar results were presented by [PERSON] et al. [31] in Tana basin in Ethiopia. However, [PERSON] et al. [46] obtained opposite results to those presented in this study for an aquifer located in hyperarid deserts in central Egypt.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**DWQI** & **Classification of Water** & **Samples** & **\% of Samples** \\ \hline \textless{}50 & Excellent water & 24 & 70.5 \\
50-100 & Good water & 10 & 29.5 \\
100–200 & Poor water & 0 & 0 \\
200–300 & Very poor water & 0 & 0 \\ \textgreater{}300 & Unsuitable for drinking & 0 & 0 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Classification of the water quality index and percentage of the values of the Cuernavaca aquifer samples.  
Figure 10: Variation of the water quality index in the sampling wells of the Cuernavaca aquifer.  
[PERSON] et al. [19] suggest that the groundwater chemistry of an aquifer is the result of evaporation, weathering, and rock-water interaction. In this study, the Gibbs diagram (Figure 12) showed that the cations and anions in the aquifer are primarily controlled by rock-water interaction. The dissolution of the rock in the aquifer is evidenced since a high content of chlorides and sulfates is observed. Therefore, this process regulates groundwater chemistry and quality. Likewise, this diagram suggests that the P2 site could be controlled by evaporation. This process produces dissolved solutes in groundwater and soil in areas with little depth [15; 19; 47; 48].