Abstract
Groundwater is an important freshwater source for agricultural, drinking and industrial use in arid areas. The present study integrates geographic information system (GIS), hydrochemistry, and factor analysis to assess groundwater quality under expanding agricultural activities in Qena Governorate, Egypt. A total of 73 groundwater samples were collected and analyzed for pH, electrical conductivity (EC), total dissolved solids, major cations (Ca2+, Mg2+, Na+, K+), major anions (HCO3-, Cl-, SO42-, F-), and total hardness. The spatial distribution of these analyzed physico-chemical parameters was mapped with GIS. According to the World Health Organization and Egyptian water standards, the computed water quality index shows that about 62% of the groundwater wells are suitable for drinking. Groundwater suitability for irrigation was assessed on the basis of sodium adsorption ratio (SAR), residual sodium carbonate (RSC), Kelley ratio (KR), magnesium hazard (MH). It is found that 99% of the wells are suitable for irrigation when considering the values of EC, and SAR only. However, only 50% of the wells are suitable for irrigation if Na+%, RSC, and KR are considered. Hydrochemical classification and factor analysis indicate that the groundwater is Na+-Cl-(58%) and MgCl (23%) dominant which signifies the role of evaporation under intensive irrigation and hot climate. Dissolution of evaporites loads the system with Na+ and Cl-whereas return flow from irrigation transports solutes to groundwater. Increasing Mg2+ is due to dolomitic dissolution and the use of fertilizers. Moreover, ionic exchange activities increase Na+ concentration in the groundwater at the expense of Ca2+, but does not affect Mg2+. The integration of traditional hydrochemical analysis and GIS with factor analysis is useful to understand the factors controlling groundwater chemistry and may aid decision makers toward effective groundwater quality management.