Journal of African Earth Sciences 181 (2021) 104260 Available online 22 May 2021 1464-343X/© 2021 Elsevier Ltd. All rights reserved. Hydrochemical characteristics and quality assessment of groundwater aquifers northwest of Assiut district, Egypt Esam Ismail a , Ahmed Abdelhalim a, b, * , Mohamed Abou Heleika a a Department of Geology, Faculty of Science, Minia University, Minia, 61519, Egypt b Department of Civil Engineering, University of Bristol, Bristol, BS8 1TR, UK A R T I C L E INFO Keywords: Groundwater quality GIS Statistical analysis Assiut district Pleistocene aquifer Drinking and irrigation 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 + > Ca 2+ > Mg 2+ > K + and Cl  > HCO  3 >SO  4 but it takes the trend of Na + > Mg 2+ > Ca 2+ > 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. 1. Introduction Freshwater resources are very limited, and their defciency has become a critical apprehension worldwide. In arid and semi-arid areas, assessment and management of groundwater quality are very important for maintaining freshwater resources and for sustainable development. Local policymakers and water resource managers determine the usage of water for either drinking or agricultural purposes based on the quality of the groundwater in various areas (Asadi et al., 2020). In Egypt, the pollution increases, and the future of the water situation is not optimistic due to climate change and the construction of the Ethiopian Renaissance Dam that will lead to the degradation of the freshwater sources. These challenges increase the need for groundwater uses in Egypt. Moreover, land reclamation projects expansion is the vital aim of the Egyptian government to satisfy the needs of the population of water and food. The reclamation of desert areas requires the exploration of new water resources. Therefore, Egypt has planned to start to reclaim 4 million acres in 2016. The only source of water in these regions is groundwater. Different studies were carried out to assess the groundwater suitability for different purposes by different methods in different areas around the world e.g., (Asadi et al., 2020; Gauns et al., 2020; Singh et al., 2020, and Berhe, 2020). In Egypt, groundwater has been assessed by many authors e.g., (Ismail et al., 2017, 2020; Abou Heleika et al., 2018a,b; Ismail and El-Rawy, 2018a,b; Abd-Elaty et al., 2019; El-Rawy et al., 2019; M. G. Snousy et al., 2019; Geriesh, 2019; Elsayed Gabr et al., 2020; Abdalazem et al., 2020; and Sharaky et al., 2020). Furthermore, many authors studied the hydrogeological and hydrogeochemical conditions of the investigated area and its vicinities. Attia (1974) studied the general parameters and characteristics of the groundwater aquifer in the Nile Valley. Hefny (1977), made a good description of the fuctuation of the water level in some drilled well at the Nile Valley and determined their water type. Attia et al. (1986) made a hydrogeologic budget analysis for * Corresponding author. Department of Civil Engineering, University of Bristol, Bristol, BS8 1TR, UK. E-mail address: ahmed.abdelhalim@bristol.ac.uk (A. Abdelhalim). Contents lists available at ScienceDirect Journal of African Earth Sciences journal homepage: www.elsevier.com/locate/jafrearsci https://doi.org/10.1016/j.jafrearsci.2021.104260 Received 6 April 2020; Received in revised form 22 April 2021; Accepted 11 May 2021