All of Lebanon’s aquifers, without exception, are afflicted with some form of contamination, be it from untreated raw sewage, pesticides or fertilizers, but at the forefront there is seawater intrusion, and nowhere it is more pronounced than in Beirut, the capital. Extensive sampling of Beirut’s groundwater in recent years has revealed alarming values of Total Dissolved Solids (TDS) in the thousands of milligrams per litre, in an increasing number of wells. This irreversible deterioration of groundwater quality is forcing citizens to install costly desalination equipment, importing questionable water by private tankers or abandoning their wells altogether. Initial groundwater sampling began in 2004. In what was possibly Lebanon’s worst drought in decades, another campaign to sample Beirut’s groundwater was undertaken in the summer of 2014 which still continues to date. Acute water shortages in recent years coupled with recurrent periods of drought, have rendered Total Dissolved Solids (TDS) of many sampled wells in Beirut, equivalent to that of seawater (~37,500 mg/L). Fundamental in combating the impact of seawater intrusion however is an understanding of the Ghyben-Herzberg principle which warns that for every meter of groundwater drop above sea level there is an equivalent rise of 40 meters of the saline-fresh water interface, demonstrating just how sensitive over-pumping is in coastal aquifers. With an understanding of the principle dynamics behind the phenomena of seawater intrusion, myriad methods may then be employed to combat this encroachment in coastal aquifers. Restricting or even preventing altogether withdrawals from Beirut’s coastal aquifers may however be the only viable option left.
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