## 4 Conclusions  
The recorded pattern of cations and anions in the spring and drilled-well water samples of the El-Farafra Oasis was Ca\({}^{2+}\) > Na\({}^{+}\) > Mg\({}^{2+}\) > K\({}^{+}\) and HCO\({}_{3}\)\({}^{-}\) > Cl\({}^{-}\) > SO\({}_{4}\)\({}^{2-}\), respectively. The dominant phytochemical facies in the area investigated are of the alkali-earth type (Ca/MgCl\({}_{2}\)) having no dominant ion, followed by magnesium-bicarbonate (Mg(HCO\({}_{3}\))\({}_{2}\)) type water, and the remaining belonging to the sodium-chloride water type. Groundwater chemistry in the study area is mainly controlled by rock-water interaction, particularly the dissolution of carbonate rocks and silicate weathering. Groundwater samples in the El-Farafra Oasis aquifer are characterized by deep meteoric origin, slightly acidic to neutral, soft, and within the permissible limits of WHO (2017) for TDS, EC, Ca\({}^{2+}\), Mg\({}^{2+}\), HCO\({}_{3}\)\({}^{-}\), SO\({}_{4}\)\({}^{2-}\), Cl\({}^{-}\), NO\({}_{3}\)\({}^{-}\), NO\({}_{2}\)\({}^{-}\), NH\({}_{4}\)\({}^{+}\), TP, and SRP. The assessment of groundwater suitability for drinking purposes revealed that the water samples from the study area fall in the 'excellent' to 'good' classes. However, the evaluation of groundwater suitability for irrigation revealed that they fall in the 'excellent' to 'good' categories, except in the case of magnesium hazard which causes 6.3% of the wells and springs studied to be unsuitable for irrigation. Overall, the springs and drilled wells studied in the El-Farafra Oasis are highly amenable to the optimum-development strategy recently applied in the Western Desert of Egypt. Conceptualization, A.A.S., S.U.B. and M.C. ; methodology, J.G., S.U.B., A.H. and H.G. ; software, S.U.B., A.H. and H.G. ; validation, A.G., A.A.S. and M.C. ; formal analysis, J.G., S.U.B. and A.H.; investigation, J.G., H.G., S.U.B. and A.H.; resources, A.A.S. ; data curation, H.G., S.U.B. and A.H.; writing--original draft preparation, S.U.B., A.H., H.G. and A.A.S. ; writing--review and editing, A.G. and M.C. ; visualization, A.G. and M.C. ; supervision, A.G. and M.C. ; project administration, M.C. ; funding acquisition, M.C. and A.A.S. All authors have read and agreed to the published version of the manuscript. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameters** & **PC1** & **PC2** \\ \hline
**pH** & 0.655 & \(-\)0.463 \\ \hline
**E.C.** & 0.946 & 0.173 \\ \hline
**T.D.S.** & 0.942 & 0.181 \\ \hline
**Ca\({}^{2+}\)** & 0.952 & 0.134 \\ \hline
**Mg\({}^{2+}\)** & 0.953 & 0.123 \\ \hline
**Na\({}^{+}\)** & 0.964 & 0.036 \\ \hline K\({}^{+}\) & 0.681 & \(-\)0.454 \\ \hline
**HCO\({}_{3}\)\({}^{-}\)** & 0.794 & 0.422 \\ \hline Cl\({}^{-}\) & 0.615 & \(-\)0.311 \\ \hline
**SO\({}_{4}\)\({}^{2-}\)** & 0.956 & 0.179 \\ \hline
**NO\({}_{2}\)\({}^{-}\)** & 0.793 & \(-\)0.113 \\ \hline
**NO\({}_{3}\)\({}^{-}\)** & 0.889 & \(-\)0.0321 \\ \hline
**NH\({}_{4}\)\({}^{+}\)** & 0.802 & \(-\)0.137 \\ \hline
**TP** & \(-\)0.1307 & **0.755** \\ \hline
**SRP** & 0.024 & **0.636** \\ \hline
**Eigen values** & 9.47 & 1.83 \\ \hline
**Variability (\%)** & 59.230 & 12.0 \\ \hline
**Cumulative (\%)** & 59.230 & 61.230 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Principal component analysis (PCA) and loadings of the water quality parameters for the entire dataset. **Funding:** This research was a part of the PhyBiO project, partially funded by MUSE--Museo delle Scienze, Trento, Italy, and the Italian Ministry of Foreign Affairs and International Cooperation (MAECI) to the former MUSE [PERSON] for the academic year 2018/2019. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** Not applicable. **Acknowledgments:** Authors are very thankful to their home universities and institutions for allowance to conduct this research. We are also thankful to [PERSON], the responsible manager of the White Desert National Park, for his kind support during materials sampling.