Major Problems Affecting the Principal Aquifers in Lebanon

Groundwater is the main source of water in Lebanon. The principal aquifers in the country, however, are affected or threatened by groundwater mining, seawater intrusion from the Mediterranean Sea, and contamination by raw sewage. Three of these aquifers are the focus of this study: the Damour Aquifer in central Lebanon, which supplies the capital Beirut, the Koura-Zgharta Aquifer in the north, which supplies Tripoli, the second largest city in the country, and the Sannine Aquifer in the south, which supplies Saida. The three aquifers are highly fractured karstic limestone aquifers.

Poor management of water resources and high demands for water in the three cities, where the population density is the highest in the country, has led to overpumping of groundwater. This situation has resulted in mining of groundwater in the Koura-Zgharta Aquifer, at a rate of 3.8 million m3/year, and seawater intrusion in the Damour Aquifer. The Koura-Zgharta Aquifer is also threatened by seawater intrusion at some locations. At the current rates of pumping, the Damour Aquifer will also be subjected to groundwater mining in a few decades. The current rate of saltwater encroachment in the Damour Aquifer is 195 m/year. At the present time, the quality of water in the aquifer is suitable for drinking only at wells located more than 1.5 km from the shore. In addition to groundwater mining and seawater intrusion, continued overpumping of the three aquifers will also increase the risk of land subsidence in the three heavily populated cities.

In the three cities, and Lebanon in general, raw wastewater is predominantly directed to the ground, where the highly fractured and permeable limestone strata enhance its transit to groundwater. As a result, groundwater from many springs and public water-supply wells in the Sannine Aquifer and the Koura-Zgharta Aquifer is contaminated by raw sewage.