## 3 Results and Discussion  
### Descriptive Analysis of Groundwater Quality Parameters  
The total dissolved solids reflect the behavior of the salt concentration of the aquifer. These solids were found in a range of 75-688 mg/L and a mean value of 316 mg/L was registered. This value is low compared to that reported by [PERSON] et al. [31], who found concentrations up to 277.6 mg/L. According to WHO [28], groundwaters with TDS values higher than 500 mg/L could be considered unsuitable for drinking water supply. The total hardness was found in a range of 24.6-456.8 mg/L. However, the mean value (179.2 mg/L) is below the concentration of 300 mg/L suggested by WHO [28] for drinking water. This value is also below the total hardness found by [PERSON] et al. [8], who presented concentrations greater than 292 mg/L in an unconfined aquifer located in the Central Ganga Basin, India. The electrical conductivity of the Cuernavaca aquifer was between 90 and 991 uS/cm with a mean conductivity of 409.8 uS/cm. A high variation of electrical conductivity was observed in this aquifer, where the lowest conductivity values were found in sampling well one. Anthropogenic activities, such as agriculture, and rainwater filtration could be the reason for this variation. [PERSON] et al. [38] presented concentrations up to 11,950 uS/cm in the unconfined Doukkala Aquifer located in a large agricultural region in Morocco. The groundwater of the Cuernavaca aquifer is slightly alkaline since its pH is in the range of 6.2-8.4 (the water is considered alkaline when pH > 8 and acidic when pH < 6). This pH range is within the drinking water standards of the WHO (6.5-8.5). Nitrogen and phosphorus were below the permissible limits proposed by local standards. The TN and TP concentrations found were between 0.012-7.02 and 0.001-0.39 mg/L, respectively. Nitrogen concentrations are not usually frequent in natural soils, they occur due to the contact of the soil cover with nitrated fertilizers, animal waste, domestic effluents, and septic tanks [14]. The total organic carbon was found in a range of 0.07-2.57 mg/L. The presence of organic matter in the Cuernavaca aquifer could be related to the infiltration of the organic matter produced naturally by plants and animals due to excretion and decomposition. This situation is corroborated since fecal coliforms were found in the aquifer, \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Indices** & **Acronym** & **Equation** & **References** \\ \hline Sodium adsorption ratio & SAR & \(\text{SAR}=\frac{\text{Na}^{+}}{\sqrt{\frac{\text{C}^{2+}}{\text{Mo}^{2+}}}}\) & [PERSON] et al. [34] \\ Soluble sodium percentage & SSP & \(\text{SSP}=\frac{\text{Na}^{+}}{\text{Ca}^{2+}+\text{Mg}^{2+}+\text{K}^{+}}*100\) & [PERSON] et al. [31] \\ Sodium percentage & \%Na & \%Na & \(\frac{\text{(Na}^{+}+\text{K)}}{\text{(Ca}^{2+}+\text{Mg}^{2+}\text{Na}^{+}+ \text{K}^{+})}*100\) & [PERSON] et al. [36] \\ Residual Sodium Carbonate & RSC & \(\text{RSC}=\left(\text{HCO}_{3}^{-}\right)-\left(\text{Ca}^{2+}+\text{Mg}^{2+}\right)\) & [PERSON] et al. [16] \\ Magnesium Hazard & MH & \(\text{MH}=\frac{\text{Mg}^{2+}}{\text{Mg}^{2+}+\text{Ca}^{2+}}*100\) & [PERSON] et al. [37] \\ Permeability index & PI & \(\text{PI}=\frac{\text{Na}^{+}+\text{K}^{+}+\sqrt{\text{RCG}_{3}^{2}}}{\text{Ca }^{2+}+\text{Mg}^{2+}+\text{Na}^{2+}+\text{K}^{+}}*100\) & [PERSON] et al. [8] \\ Kelly Ratio & KR & \(\text{KR}=\frac{\text{Na}^{+}}{\text{Mg}^{2+}+\text{Ca}^{2+}}\) & [PERSON] et al. [27] \\ Total Hardness & TH & \(\text{TH}=\left(\text{Ca}+\text{Mg}\right)*50\) & [PERSON] et al. [31] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Groundwater indices based on hydrochemical features. with a mean value of 276.6 CFU/100 mL. The presence of fecal coliforms in groundwater could indicate pollution from anthropogenic sources since the sampling wells are in an urban area with a large population. Table 2 presents the mean values of the water quality parameters measured in the Cuernavaca aquifer from 2012 to 2019.