Using chlorine isotopes as chemical tracers, a University of Delaware (UD) study aimed to determine the age and origin of groundwater in the Eastern Desert of Egypt. According to Phys.org, the research was done by UD doctoral candidate Mahmoud Sherif, UD Chair of Geological Sciences Neil Sturchio, and Western Michigan University Chair of Geological and Environmental Sciences Mohamed Sultan.
Egyptian water authorities have recently given renewed attention to groundwater, even though it only provides 7% of the water demand in Egypt. Authorities hope this will mitigate water stress and accommodate agriculture projects.
According to Phys.org, researchers used the radioactive isotope chlorine-36 to estimate the age of the groundwater, using 29 samples collected from wells.
Sturchio said the Eastern Desert gets more rain than the Western Desert of Egypt despite its arid climate. Researchers wanted to see if groundwater in the Eastern Desert might be younger than the water found in the Western Desert, according to Phys.org.
"In the shallow aquifers you would expect young water, perhaps 50 to 100 years old, because it's coming down as rain and flowing out towards the Nile Valley," Sturchio said to Phys.org. "But in some of these aquifers, Mahmoud found water that's apparently 200,000 years old."
Finding natural discharge from the deep aquifers through these faults to shallow aquifers is important for the developmental plan of the area, Sherif said.
"When we quantify the amount of water in the shallow aquifer, we have to consider the water coming up from the deeper aquifer," Sherif said. "It's an additional source and instead of drilling very deep wells, which is very expensive, the [Egyptian government] won't have to. They can reduce the cost."
Only so much water can be taken out of the river, Sturchio said, and it is critical in areas such as the Eastern Desert to identify these groundwater resources.
"The young groundwater that comes down as rain and takes about 50 to 100 years to flow to the Nile is being used for irrigation in some places. But some of the water they're pumping out comes from the much older groundwater in aquifer underneath," Sturchio said. "You really want to know how much of that water you can pump out before you're over-pumping it and using it up too fast. You don't want to pump it out faster than it can replenish itself, ideally. Knowing the groundwater age is part of the basis for developing a good strategy for using it."
