Hydrochemical characteristics and quality assessment of groundwater aquifers northwest of Assiut district, Egypt

Abstract

Groundwater quality assessment is essential for the sustainable development of groundwater resources and for determining their use for domestic, irrigation, or industrial purposes. The objective of this study is to determine the hydrochemical characteristics and water quality of the groundwater aquifers in the area to the northwest of Assiut district, Egypt, and to map their spatial variations in terms of suitability for domestic and irrigation purposes. Two main aquifers are presented in the study area, the Pleistocene and the Eocene aquifers. Water samples were collected from 58 wells across the study area and analyzed to determine their physicochemical properties and calculate the water quality indices. The hydrochemical investigation shows that the domination of the major ions in the Pleistocene aquifer is in the following order: Na+ > Ca2+ > Mg2+ > K+ and Cl− > HCO−3 >SO−4 but it takes the trend of Na+ > Mg2+ > Ca2+ > K+ and Cl− > HCO−3 >SO−4 in the Eocene aquifer. Most of the Pleistocene aquifer samples are suitable for drinking while about a half of the Eocene samples are unsuitable for drinking due to their high salinity that ranges from 235 to 2830 for the former and from 350 to 4150 for the latter. The Eocene water samples and most of the Pleistocene water samples are unsuitable for domestic use due to the high level of hardness that ranges from 67.88 to 1923 for the former and from 26.56 to 944.6 for the latter. Groundwater suitability for irrigation was assessed based on sodium adsorption ratio (SAR), residual sodium carbonate (RSC), Kelley ratio (KR), the magnesium hazard (MH), and potential salinity (PS). Most of the Pleistocene and a half of the Eocene samples are suitable for irrigation. Maps showing the spatial variations of different groundwater quality parameters were produced using ArcGIS.