_applied sciences_  
_Article_  
**Spatiotemporal Changes in the Hydrochemical Characteristics and the Assessment of Groundwater Suitability for Drinking and Irrigation in the Momag Coastal Region, Northeastern Tunisia**  
[PERSON] 1,2,3, [PERSON] 1, [PERSON] 2,*\({}^{\copyright.com}\) and [PERSON] 3  
1 Research Laboratory of Environmental Science and Technologies, High Institute of Environmental Science and Technology (HIEST) of Borj Cedria, University of Carthage, Amilcar 1054, Tunisia; [EMAIL_ADDRESS] (E.H.); [EMAIL_ADDRESS] (A.B.M.)  
2 Earth Sciences Department, Sapienza University of Rome, 00185 Rome, Italy  
3 Centre of Water Research and Technologies, University of Carthage, Amilcar 1054, Tunisia; [EMAIL_ADDRESS]  
* Correspondence: [EMAIL_ADDRESS]  
[PERSON], [PERSON]; [PERSON], [PERSON]; [PERSON], [PERSON]; [PERSON], [PERSON] Spatiotemporal Changes in the Hydrochemical Characteristics and the Assessment of Groundwater Suitability for Drinking and Irrigation in the Momag Coastal Region, Northeastern Tunisia. _Appl. Sci._**2023**, _13_, 9887. [[https://doi.org/10.3390/app13179887](https://doi.org/10.3390/app13179887)]([https://doi.org/10.3390/app13179887](https://doi.org/10.3390/app13179887))  
Academic Editors: [PERSON] and [PERSON]  
Received: 27 July 2023  
Revised: 23 August 2023  
Accepted: 26 August 2023  
Published: 31 August 2023  
**Copyright**: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ([[https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/)]([https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/))).  
**Abstract**: Hydrogeochemical properties and groundwater quality assessment are very important for the effective management of water resources in arid and semiarid regions. The present investigation is a spatiotemporal analysis of groundwater quality using both chemical analysis and water quality indices (WQIs) in the Momag Basin in northeastern Tunisia. The results exhibit that the Mornag shallow aquifer is dominated by chloride-sodium-potassium water facies, which progress over time toward chloride-sulfate-calcium and magnesium water facies. This may highlight that the mineralization of groundwater, which increases in the direction of groundwater flow, is primarily controlled by a natural process resulting from the dissolution of evaporative minerals and cation exchange with clay minerals relatively abundant in the study area. The anthropogenic activities represented by the return flow of irrigation water, the recharge by wastewater, and climate change also have a key role in groundwater contamination. The temporal evolution in %Na and SAR over the last three years in the Mornag aquifer shows an increasing trend that makes them unsuitable for irrigation. These findings highlight the need for assessing water quality in mapping local water resource vulnerability to pollution and developing sustainable water resources management.  
**Keywords**: hydrogeochemical; spatiotemporal evolution; Momag shallow aquifer; WQI; unsuitability