Characterization and management evaluation of the nubian sandstone aquifer in Tazerbo wellfield of the Libyan man-made river project

Abstract

Tazerbo water wellfield, located in southeast Libya, was constructed as part of the first stage for the Man-Made River Project (Eastern System) during 1995–2003. A group of land subsidence forms was discovered approximately 30 km north of the wellfield two years after production, which began in March 2004. The wellfield production rate is only about one-third of its designed capacity. In addition to the land subsidence, there is a problem with the natural groundwater quality represented by high iron and manganese concentrations. This research aims to characterize the aquifer system and assess the current condition of the wellfield since its operation in 2004 in terms of groundwater quality and quantity. It further evaluates current groundwater management practices. The geographic information system was used to map hydrogeologic data of drilled water wells and groundwater monitoring data from 2003 to 2019. The aquifer system characterization showed that the exploited aquifer has excellent hydraulic properties and promising potential for future groundwater utilization. The measured drawdown during 2019 shows a maximum decline of 28 m. Moreover, the average water production is about 322,270 m3/ day, equivalent to 32% of the total abstraction proposed to the end of the year 2020 of about 1907 million m3. As far as Groundwater quality is concerned, there has been no change in water quality since the beginning of abstraction. This research indicates that current policy and institutional approaches and practices promote the optimum management of the wellfield’s water resources.