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Mersa Matruh area lies directly on the northwestern coast of Egypt; it represents a pilot area for new development projects. Quaternary Oolitic limestone constitutes the main groundwater aquifer; rainfall is the only source of groundwater recharge. Inspection of rainfall data revealed appreciable decrease in annual rainfall rates during the last decade, these lefts negative impacts on groundwater recharge. Moreover, man made dams that constructed at the upstream portions of main wades decreased surface and subsurface water flow to the downstream portions. Large decreases in groundwater levels and increase in water salinity values were recorded at such localities.
Groundwater quality and saltwater intrusion were studied. Field and laboratory investigation have been conducted. Thirty groundwater samples were collected and examined for major chemical elements (K, Na, Ca, Mg, Cl, SO4, HCO3, and CO3), minor and trace elements (Fe, Mn, Zn, Sr, Br, Li, Pb, Cu, and Cd) and nutrients (NO3, PO4, NH4). Salt-fresh water relationships and zone of dispersion of the concerned aquifer were determined. The results revealed high percentage of seawater in the majority of groundwater samples, which reflects salt-water encroachment and long distance of dispersion zone from sea. Nutrients (NO3, PO4, NH4) and bacteriological count show also high levels more than the recommended limits at many localities which reflect pollution due to agricultural and sanitary waste. Groundwater became unsuitable for domestic and agricultural purposes at many localities. The application of the thermodynamic software "Net path" in terms of balances indicates high concentration of marine minerals in groundwater, which reflects salt-water intrusion, and depletion of recent recharge component.
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