**Hydrochemical Investigation and Quality Assessment of Groundwater in the BouHafna-Haffouz Unconfined Aquifers, Central Tunisia of Groundwater in the BouHafna-Haffouz Unconfined Aquifers, Central Tunisia**

**Hydrochemical Investigation and Quality Assessment** 

DOI: 10.5772/intechopen.72173

Hatem El Mejri, Amor Ben Moussa, SarraBel Haj Salem and Kamel Zouari and Kamel Zouari Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

Hatem El Mejri, Amor Ben Moussa, SarraBel Haj Salem

http://dx.doi.org/10.5772/intechopen.72173

#### **Abstract**

Multivariate statistical techniques were applied to improve the understanding of the aquifers hydrodynamic and to identify the natural and anthropogenic processes that control the BouHafna and Haffouz groundwater quality. Some other parameters, such as sodium adsorption ratio (SAR), percent sodium (%Na), residual sodium carbonate (RSC), and permeability index (PI), were used to examine the suitability of groundwater for irrigation applications. Groundwater samples are classified into Ca-Mg-HCO<sup>3</sup> and Ca-Mg-SO<sup>4</sup> water-type. The statistical investigation permits to identify three different groups. The first group reflects the influence of water-rock interaction in relation with the dissolution of evaporatic minerals, the cation exchange process with phyllosilicates and the dedolomitization. The second and third groups, including the weakly mineralized groundwater samples, suggest, firstly, that the return flow of irrigation waters has a small, but not negligible contribution to the groundwater contamination, and secondly, the reduction of nitrate (NO<sup>3</sup> ) to nitrogen gas (N<sup>2</sup> ). Furthermore, it has been demonstrated that the majority of the groundwater samples are suitable for irrigation uses.

**Keywords:** Central Tunisia, statistical techniques, water-rock interaction, dissolution, cation exchange, suitable, irrigation uses
