Demarcation of groundwater quality for irrigation purposes in Sirte, Libya

This study aimed to check the groundwater quality for irrigation in Al-Swawa, Sirte District (Libya), from the dug wells and open ground tanks supplied from the Great Man-Made River. Water samples were collected, and following parameters were analyzed: pH, electrical conductivity (EC), sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), chloride (Cl-), and bicarbonate (HCO3-). Sodium adsorption ratio (SAR), soluble sodium percentage (SSP), ratio of sodium carbonate (RSC), magnesium adsorption ratio (MAR), Kelly's ratio (KR), permeability index (PI), and total hardness (TH) were calculated. The results showed wide variations in water quality parameters for both sources of water. Mean values for pH of 7.7 and 8.4, EC of 8.0 and 0.7 dS m(-1), and SAR of 12.0 and 4.8 mg L-1 were recorded at wells water and Great Man-Made River water, respectively. Well waters were classified as a very high salinity, while Great River were classified as a medium hazard. Well waters gave values of Cl- varies from 13.0 to 51.5 mg L-1, while Great Man-Made River gave values less than 10 mg L-1, which classified as moderately Cl- hazard. Except a sample of the wells, all analyzed water samples showed values of SSP more than 60%, which exceed Eaton's measure value. It is concluded that, wells water just suitable to irrigate a very salts tolerant crop, while the Great Man-Made River water is suitable for irrigation with moderate leaching if intensive management is adopted and followed.