Geochemical evolution and recharge of the shallow aquifers at Tulul al Ashaqif, NE Jordan

Shallow aquifers in the Tulul Ashqaf area in northeast Jordan represent areas where relatively high recharge is occurring in an and environment. The significance of this phenomenon in terms of potential for water resource development in the area is related to the amount of recharge that is occurring as well as factors that may affect the water quality within the aquifers. Modeling of the geochemical evolution of these waters gives insight into these issues. Chemical data from rainwater, surficial salts, crushed basalt samples, runoff, and groundwaters were collected, and the chloride mass balance approach was used by integrating these various data into geochemical mass balance models using NET-PATH. Variations between rainwater chemistry, the surficial salts and basalt, and runoff exist, suggesting various processes and sources, and allows determination of the input into the groundwater. Geochemical modeling shows that the majority of chloride added to the groundwater after runoff events was salt from surface deposits, and that the rainwater had undergone only small amounts of evaporation. Isotopic investigations of O-18/O-16 and H-2/H-1 of the waters confirmI this result. The results indicate that most of the water that falls over the study area percolates to the shallow groundwater with little evaporation. Less than 25% of the water evaporates prior to recharge. Water stored in the aquifer is affected by water-rock interaction and little evidence suggests that evaporation is a factor in the chemical evolution of the waters of the shallow aquifers, except in areas where salt efflorescence occurs.