Groundwater Potential in the Central Part of Al Jabal Al Akhdar Area, NE Libya

Al Jabal Al Akhda in the north-eastern part of Libya represents a region with promising ecological underpinning for grazing and other agricultural developments. In its central part, groundwater in the karstified Eocene and Upper Cretaceous limestone aquifer is the main source of water for drinking, agriculture, and grazing, and there is now considerable groundwater extraction. The groundwater potential was studied based the available literature and inquiries to water institutions in Libya, with responsibility to identify and classify the main resources and preview their status to highlight the major issues regarding resources management and their sustainability. Furthermore, a complete database for about 112 water wells drilled in the period 2003-2009 was used for the evaluation of the two aquifers. In this research, the hydrogeological methods will be integrated with the Geographic Information System (GIS) that played a main role in highlighting the spatial characteristics of the groundwater system. The results indicate that the depth to water for the Upper Cretaceous aquifer ranges from 150 m to 458 m, and the piezometric surface decreases from over 500 m (m.s.l) in the northern parts of the study area to -20 m (m.s.l) in southeastern part. Salinity ranges between 303 and 1329 mg/l indicating that groundwater belongs to the slightly fresh water class. In the Eocene aquifer, the depth to groundwater ranges from 120 m to 290.5 m and the potentiometric level decreases gradually southwards from 220 m (m.s.l) to -51 m (m.s.l) and characterized by steep slope in the southeastern part of the study area, where the aquifer characterized by relatively high productivity (specific capacity ranges between 10.08 and 332.3 m2/day). The groundwater salinity within this aquifer ranges between 198 and 2800 mg/l (fresh to brackish water class). The annual average rainfall (from 280 mm to 500 mm) plays a significant role in the recharge of the two aquifers. The priority of groundwater quality and potentiality increases towards the central and northern portions of the concerned area.