A multi-isotopic evaluation of groundwater in a rapidly developing area and implications for water management in hyper-arid regions

Management of water resources in hyper-arid areas faces vital challenges in a global climate change context. Consequently, understanding the effects on groundwater sources can help mitigating the problem of water scarcity and the negative impact of human intervention on the environment. A case study area in the hyper-arid climate of the United Arab Emirates, was tackled here with the focus on applying stable isotopes as tools for evaluating groundwater sources and quality assessment. The results of major ions indicate variable increase in groundwater salinity moving away from Al Hajar Mountains recharge areas to the discharge areas (Arabian Gulf coast). The data of stable isotopes (δ18OH2O, δ2HH2O, δ18ONO3, δ15NNO3, δ18OSO4, δ34SSO4, δ11B) suggest impact of paleo-groundwater in the abstractions of the wells nearest to the coast. Nitrate isotopes indicate farming activities sources that can be masked due to the contribution from the nitrate-poor paleo-groundwater. Nitrate reduction processes are expected near to the recharge front. Sulphate and boron isotopes further suggest that influence of ancient evaporite dissolution in salinization. Management efforts should be focused on the diffuse sources of quality mitigations that can be vital in fingerprinting local and regional (transboundary) effects. [Display omitted] •Stable isotopes are powerful in revealing groundwater sources in hyper-arid regions.•Isotopic data indicate modern recharge modified by paleo/anthropogenic water.•Paleo-groundwater represents an important portion of abstracted groundwater.•Abstraction from deep aquifers can dilute nitrates, but increase the salinization.