ASSESSMENT OF GROUNDWATER QUALITY OF THE QUATERNARY AQUIFER IN THE EASTERN PART OF THE NILE DELTA

The study area lies in the eastern part of the Nile Delta. It is bounded on the north by El-Manzala Lake, on the east by the Suez Canal, on the west by the Nile Damietta Branch and on the south by the fresh water Ismailia Canal. Groundwater quality has been determined based on a hydrochemical investigation of the Quaternary aquifer in the study area. Forty-six water samples from groundwater monitoring wells and four water samples from the main irrigation canals in the study area were collected and analyzed for various hydrochemical parameters. The groundwater samples are classified into fresh water types (Ca-Na-Mg-HCO₃ and Na-Mg-Ca-HCO₃-Cl-SO₄) in the southern parts, brackish water types (Na-Ca-Mg-Cl-HCO₃) in the central parts, and saline water types (Na-Cl and Na-Ca-Cl) in the northern and eastern parts of the study area. The hydrochemical facies showed that the majority of samples were enriched in sodium, chloride and bicarbonate; this reflects the effect of salt water and fresh water bodies on the shallow Quaternary aquifer. Total dissolved solids (TDS), total hardness (TH) and electrical conductance exceed the desirable limits in the northern part of the study area. The calculated values of sodium adsorption ratio (SAR), salinity, residual sodium carbonate (RSC) and sodium content (Na %) indicate unsuitable water for irrigation in the northern part to excellent water in the southern and central parts of the study area. For drinking water purposes, the results showed that about 30.43% of the total analyzed samples are acceptable, 26.08% are unsuitable and 43.47% are permissible according to WHO standards.