Hydrochemical and statistical study of the groundwater salinization in the region of Gabes in Tunisia

Abstract

Marine intrusion is the most serious problem facing aquifers in coastal areas. These aquifers are considered as important sources of freshwater, especially in arid areas. The Gabes Jeffara aquifer, located in south-eastern Tunisia, has been recognized as an industrial area specialized in mining phosphate processing industry. Furthermore, the region has also been intensively exploited to supply the growing needs of agriculture and domestic sectors. Degradation of groundwater and the possibility of marine intrusion became a serious concern of the communities. This work proposes a multidisciplinary investigation involving hydro-geochemical and geostatistical techniques to investigate the characteristics of groundwater quality and identify the origin of its salinization. For this purpose, 43 water samples were conducted and analyzed in different locations of the study area (Ghannouch and Mareth cities). Electric conductivity, pH, salinity and major ions were measured and analyzed. Piper and pie diagrams, and geostatistical analysis were used to assess groundwater mineralization. Results show that dominant chemical facies are Na-Cl-Ca-SO4 (sodium, chloride, calcium, sulphate) due to rock-water interaction, suggesting that dissolution of halite was the main mineralization source of groundwater in the study area. However, saltwater intrusion was shown to control groundwater quality in some points so we can talk about a local saltwater intrusion.