Evaluation of groundwater quality for drinking and irrigation purposes in the north-western area of Libya (Aligeelat)

Groundwater is considered an important water source for agricultural, drinking and domestic uses in many regions of the world including Libya, especially in its coastal area. This study aims to assess the quality of groundwater in north-western area of Libya for drinking and agricultural through examining its physico-chemical characteristics such as pH, electrical conductivity (EC), total dissolved solids (TDS), total hardness, cations and anions. These parameters are used to assess the suitability of groundwater for domestic purposes by comparing their current values with the maximum permissible limits of these parameters that are recommended by World Health Organization (WHO). The EC, sodium adsorption ratio, soluble sodium percentage, Kelly’s ratio and magnesium adsorption ratio of the groundwater are also used to evaluate its suitability for irrigation. Gibbs diagram shows the evaporation–crystallization dominance in controlling the quality of groundwater. The main hydrochemical facies is Ca–Mg–SO₄–Cl type of water in both methods of Piper and Chadha’s diagram. The results revealed that most groundwater samples were not suitable for drinking and household uses due to their high levels of most cations and anions, total hardness, EC and TDS. Most of the collected water samples showed the investigated parameter levels exceeded the permissible limits of WHO. Therefore, most of the groundwater samples are considered unsuitable for irrigation due to its high salt content, unless certain measures for salinity control are undertaken.