Recharge, timescale of groundwater flow, and geochemical evolution of the groundwater system in the Najd area, Dhofer Governorate, Sultanate of Oman

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The research hypothesis examined in this project says that groundwater of the arid Najd area in southwestern Oman originated from infiltration of monsoon precipitation in the Dhofar mountain range with minor contributions from indirect recharge via Wadis. Due to past climate change most of the groundwater may have been recharged at higher rates several thousand years ago compared to current recharge making most of the groundwater a fossile and hence non-renewable resource. The geochemical evolution of the groundwater is not only controlled by water-rock interaction during flow of groundwater following the incline of the aquifer formations towards the north but also by mixing between the different aquifers. The main goal of the proposed study is to assess the key aspects of the water balance that will lead to a comprehensive and reliable knowledge about recharge, flow, and transport processes in the Najd aquifers. The methodological approach proposed is a state-of-the-art combination of hydrochemical and isotope investigations with basic hydrological and hydrogeological field work. Hydrochemistry (major and trace elements) and environmental isotopes (18O, 2H, 3H/3He, SF6, 14C, 13C, noble gases) will be used to get reliable data on groundwater origin, age, and flowpaths. Together with hydrogeological data these parameters will be used to develop a comprehensive conceptual hydrogeological flow model of the Najd aquifers.