TITLE:
Water Quality Evolution of the Upper Cretaceous to Recent Aquifers in Jordan
AUTHORS:
Elias Salameh, Ghaida Abdallat
KEYWORDS:
Natural Groundwater Qualities, Evolution, Threats of Overexploitation, Surficial, Tertiary, Upper Cretaceous Aquifers, Mobilization of Salts
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.14 No.1,
January
22,
2026
ABSTRACT: Two main porous and permeable rock sequences of Upper Cretaceous to recent ages build the near-surface aquifer systems in Jordan; the lower aquifer system of the combined Massive Limestone and Silicified Limestone composite aquifer (B2/A7) and the Chalk Marl, basalt, and recent deposits upper aquifer system (B4,5, and recent deposits). The thick Bituminous Marl Formation (B3) separates these two aquifer systems. Both aquifers receive recharge along their outcrops, resulting in fresh groundwater with low salinity. Where the Bituminous Marls confine the lower aquifer system in the Plateau area, its groundwater increases in salinity and temperature and becomes subject to reducing conditions, which is reflected in its quality. In the upper aquifer system of the Azraq, Hammad, and central Jafr areas, evaporites originating from recent playa sediments affect the fresh recharge groundwater quality, and its originally low-salinity carbonate groundwater becomes rich in chlorides and sulfates. In areas of erosion with no playas and evaporites, the water quality remains fresh and reflects water interaction with the aquifer rock matrix. In this article, the conditions and sources of increasing salinity parameters, lower pH values, higher temperatures, and H2S, concentrations in the Lower groundwater system are discussed. In addition, this article will clarify the effects of playas and mudflats on the quality of the groundwater in some areas of the surficial aquifer that do not affect other areas of the same aquifer. This study shows that the hydro-geochemical evolution of the lower groundwater systems, A7/B2, indicates that their overexploitation will lead to a reduction in the freshwater discharges from springs and seepages and to the enhancement of groundwater reactions with the confining bituminous marls, accompanied by releases of CO2 and HS gases into the groundwater of the lower aquifer. In the surficial aquifer affected by playas and mudflats, the result will be increased groundwater salinity because of the mobilization of sulfate- and chloride-rich water from the playa sediments into the fresh groundwater regimes. Therefore, great attention must be given before any decision is made to overexploit these aquifers.