Groundwater recharge and flow in the Lower Cretaceous Nubian Sandstone aquifer in the Sinai Peninsula, using isotopic techniques and hydrochemistry |
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| Authors: | S Abd El Samie M Sadek |
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| Institution: | (1) Siting and Environmental Department, National Center for Nuclear Safety and Radiation Control, Atomic Energy Authority, 3 Ahmed El-Zomor Street, Nasr City 11762, P.O. Box 7551, Cairo, Egypt, |
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| Abstract: | The present work was conducted in the Sinai Peninsula (1) to identify the recharge and flow characteristics and to evaluate
the continuity of the Lower Cretaceous Nubian Sandstone aquifer; and (2) to provide information for the aquifer's rational
appraisal. Isotopic and hydrochemical compositions combined with the geological and hydrogeological settings were used for
this purpose.
A considerable depletion in isotopic content (oxygen-18 and deuterium) and low d-excess values exist in the studied groundwater,
reflecting the contribution of old meteoric water that recharged the aquifer in pluvial times. Modern recharge also occurs
from precipitation that falls on the aquifer outcrops. The wide scatter of the data points around the two meteoric lines,
the global meteoric water line (GMWL) and Mediterranean meteoric water line (MMWL), in the δ18O–δD diagram indicates considerable variation in recharge conditions (amount, altitude, temperature, air masses, distances
from catchment, overland flow, etc.). The isotopic composition in the El-Bruk area is minimum (18O=–9.53‰), very close to the average value of the Western Desert Nubian Sandstone (18O=–10‰), where the local structural and lithologic conditions retard groundwater flow and the main bulk of water becomes noncyclic.
The continuity of the aquifer in northern and central Sinai is evidenced by the isotopic similarity between samples taken
from above and below the central Sinai Ragabet El-Naam fault, the distribution of potentiometric head, and hydrogeological
cross sections.
The combination of isotopic composition in terms of 18O and chemical composition in terms of TDS and salt contents is the basis for separating the studied groundwater into groups
that reflect the recharge sources and isotopic and chemical modifications during flow.
Electronic Publication |
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| Keywords: | Nubian Sandstone Sinai Peninsula stable isotopes groundwater recharge/water budget groundwater flow |
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