## 1 Introduction  
Water shortages in hyper-arid regions such as southern Egypt are a serious concern for hydrologists, who should evaluate and protect every accessible water source. Water scarcity in these hyper-arid areas might affect a number of activities (including the economy and human life); as a consequence, different actions are needed to avert the expected disasters and conflicts that may develop as a result of insufficient water supplies [1]. Groundwater is the second source of water used in agriculture, industry, and domestic applications [2]. Groundwater flow models are used to analyze groundwater flow behavior and recharge in vast aquifers [3], but these techniques might be challenging to implement due to a lack of datasets and the time and resources required to obtain them. For quantification of the groundwater storage changes on a regional scale, the gravity datasets from the Gravity Recovery and Climate Experiment mission, combined with other relevant information, have been extensively used in several study areas (e.g., [4; 5; 6; 7; 8; 9; 10; 11; 12; 13]). Additionally, regional and global gravity and magnetic data are used to investigate heat flow in different regions [14; 15].  
Hydro-chemically, the groundwater is influenced by precipitation, geological structure, rock type, residence time, and geochemical activity along groundwater flow paths. In this sense, it is vital and necessary to study the mechanisms that alter groundwater and its chemistry via rock interactions. The term \"water-rock interaction\" refers to how groundwater interacts with the host rocks in a unique way that changes its chemical composition and properties [16]. The primary interaction between groundwater and ambient rock formation results in minerals with unique hydrochemical compositions and stability dynamic features [17]. Interaction mechanisms result in the creation of numerous dissolved element components in the aquifer, which can influence the groundwater quality, particularly in arid zones [18; 19]. Furthermore, precipitation absorbed through the soil and sediments can dissolve carbonate minerals, such as calcite, aragonite, dolomite, and other minerals, in the flow path [20; 21; 22].  
The chemical interaction between water and rock is one of the most intriguing and intricate phenomena in water geochemistry. The composition of surface water and groundwater is determined by how water reacts to rocks and minerals. The chemical reactions of water-rock interaction at high temperatures are associated with hydrothermal features, hydrothermal mineral deposits, and geothermal fields. The surface outcrops of rocks from deeper levels of the crust, such as lower crustal and mantle exposures, typically reveal features produced by supercritical aqueous fluid interaction at extremely high temperatures. Many researchers have investigated the water-rock interaction [17; 18; 19; 22; 23; 24; 25; 26].  
The purpose of this research is to examine how the groundwater chemistry is affected by the lithologic nature and structural geology. The aforementioned aim is crucial for long-term groundwater development in hyper-arid environments. As a consequence, researchers identified the geology and geochemistry of water-bearing strata along the flow path to the analyzed aquifers. The location was chosen as an example from the hyper-arid zone to carry out this scientific approach. To interpret the hydrochemical data based on factor scores, statistical measures such as the saturation index (SI), principal component analysis (PCA), and hierarchical cluster analysis (HCA) were used [27; 28]. The SI can be used to assess the flow of groundwater in aquifer systems [29]. PCA and HCA are also used to assess the aquifer's geochemical mineralization and groundwater contamination [22; 30; 31]. PCA and HCA can also be used to describe how agricultural and mining operations affect groundwater [32].