Rock-water interaction processes based on geochemical modeling and remote sensing applications in hyper-arid environment: cases from the southeastern region of Egypt

Abstract Background The interaction between rocks and groundwater can be considered as multi-faceted processes in hydrogeology where the groundwater chemistry can be resulted from leaching and/or minerals dissolution. The scientific approach of this study based on testing the contribution of remote sensing in providing information related to rock-groundwater interaction along with the outputs of the geochemical model. The current research aims to explore the impacts of lithologic nature and structural geology on the groundwater chemistry. The mentioned objective is significant for the future sustainable development of groundwater in hyper-arid regions. Therefore, both geology and geochemistry of water-bearing formations along the flow path to the studied aquifers were identified. The area was chosen as an example from hyper-arid region to carry out this scientific approach. Results The obtained results indicate the existence of three main aquifers: Quaternary alluvial (salinity 1253 mg/l to 18,854 mg/l), Nubian Sandstone (salinity 311 mg/l to 14,388 mg/l), and fractured basement (salinity 320 mg/l to 19,375 mg/l). The results of speciation modeling showed that studied aquifers are supersaturated with gibbsite, goethite, hematite, magnetite, aragonite, calcite, dolomite, and alunite. Nubian aquifer specifically has homogeneity results due to the similarity of water-bearing and geology of watersheds (ferruginous sandstone and ironstone). Remote sensing data and digital elevation model analyses were used for generation of the thematic layers which is affecting the groundwater occurrences and quality such as geology, geomorphology, structural lineaments, slope, flow direction, drainage lines, and elevations. Conclusions The current research concluded that the groundwater chemistry can be a signature of the rock-water interaction. The potential implications of the research are represented through a priority map for groundwater exploration for both hydro-geophysical investigation and testing wells in order to evaluate the groundwater capabilities where the data from the recorded wells were used to calibrate this map

Appraisal of surface-groundwater anthropogenic indicators and associated human health risk in El Sharqia Governorate, Egypt

The aim of this study was to integrate hydrogeochemistry with multivariate statistical approach to understand the various processes that control water resources evolution/contamination in El Sharqia Governorate, Egypt with a particular emphasis on direct / indirect risks to human health. To achieve that, a collection of representative 21 groundwater and 35 drainage samples were taken, and examined for physical, chemical, and trace element measurements. Results indicated that, in shallow groundwater and drainage water samples, the relative abundance of major cations is Na+>Mg2+>Ca2+>K+ and for anions is HCO3 -> Cl->SO4 2- (on a molar basis). Natural processes involving some minerals dissolution/ precipitation and others including leaching of solid waste, overuse of agricultural fertilizers application, and high loads of discharged sewage water are various processes responsible for water resources evolution in El Sharqia governorate. Ammonia, nitrate, BOD, phosphate, turbidity, iron, manganese, lead, and aluminum concentrations were discovered to be higher than the limit set by international drinking water regulations. A risk to human health where HRI values for children were higher than those for adults when used for drinking purposes