Hydrochemical study of groundwater in Tazerbo, Libya, using statistical analysis and geochemical modeling

The hydrochemical assessment of groundwater is vital in order to constrain the sources of solutes for groundwater management and sustainability. This work uses integrated multivariate statistical analysis and hydrogeochemical modeling to define the controls on the groundwater chemistry in Tazerbo wellfield in Libya. Thirty-five water samples were analyzed where two main types of waters were distinguished: Ca–HCO3 and Mg–HCO3. Two main clusters differentiated the study area into two distinct zones, C1 in the west and C2 in the east. Four principal components were obtained from factor analysis showing the effect of water-rock interaction. Pearson correlation and cross plots of major ions revealed that the main controls on water chemistry in the west are weathering of iron rich clays, silicate weathering, and ion exchange, while the controls on the east are sulfate reduction, ion exchange, silicate weathering, and possible mixing with geothermal water rich in CO2. Temporal changes in the ionic compositions of groundwater were recorded between 2004 and that of the current study. These changes could be attributed to the change in the production and pumping strategy due to the induced land subsidence and water level decline in 2006. Moreover, several wells were abandoned during the past few years due to lack of maintenance that resulted from the political instability of the country. Therefore, they should be maintained to avoid local compositional changes due to localized pumping. Besides, water quality assessment was applied and evaluated the suitability of the groundwater for drinking and irrigation. However, higher Fe should be removed before supply. •Groundwater is noticeably clustered in two zones based on their chemical composition.•Groundwater composition is controlled by geogenic processes.•Compositional variations are controlled by aquifer characteristics and structures.•Temporal variations in composition are controlled by production schemes.