Nav: Home

The age of water

May 23, 2019

Most of the water used by people in Egypt comes from the Nile River, which originates from precipitation over mountainous areas in the Ethiopian highlands. In areas far from the Nile River Valley, however, where water is scarce and the population is growing, groundwater is the only available freshwater resource.

Knowing how much water is available in the groundwater aquifers and how fast it is being replenished is vital for providing the population with water for drinking and irrigation. Determining the age of water sources helps in those calculations.

A new study from the University of Delaware looked at chlorine isotopes as chemical tracers to determine the age and origin of groundwaters from the Eastern Desert of Egypt. The research was led by doctoral candidate Mahmoud Sherif and Neil Sturchio from UD and Mohamed Sultan from Western Michigan University. The work resulted in a paper recently published in the Earth and Planetary Science Letters journal.

While groundwater provides only seven percent of the water demand in Egypt, Egyptian water authorities have recently given renewed attention to increasing its exploitation, especially in eastern Egypt, to mitigate the growing water stress and to accommodate agriculture projects.

To measure the age and origin of the groundwater, 29 samples were collected from different wells during several field expeditions in Egypt. The researchers used the long-lived radioactive isotope chlorine-36 to estimate the age of the groundwaters; this isotope forms in the atmosphere and travels to the earth and has a half-life of 300,000 years.

Sturchio, professor and chair of the Department of Geological Sciences in UD's College of Earth, Ocean and Environment, said that the Eastern Desert is interesting because while it is still dry and arid, it gets more rain than the Western Desert of Egypt.

Because of this rain, the researchers were curious to see if the groundwater in the Eastern Desert might be generally younger than the water found in the Western Desert, but were surprised by their findings.

"In the shallow aquifers you would expect young water, perhaps 50-100 years old, because it's coming down as rain and flowing out towards the Nile Valley," said Sturchio. "But in some of these aquifers, Mahmoud found water that's apparently 200,000 years old."

Sturchio said that while the water is probably not actually 200,000 years old, the fact that it appears that way shows that older water from the Nubian Aquifer comes up along faults in the rocks and mixes in with the shallow water, carrying some of the older chlorine with it.

The water coming up from the deeper aquifer likely ended up there when the climate was much wetter -- as far back as a million years ago -- with abundant rainfall that caused a lot of water to seep into the ground and collect in the very thick, porous sandstone.

Sherif said that finding this natural discharge from the deep aquifers through these faults to the shallower aquifers is important for the developmental plan for the area.

"When we quantify the amount of water in the shallow aquifer, we have to consider the water coming up from the deeper aquifer," said Sherif. "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."

Sturchio said that while Egypt is lucky that it has a lot of water from the Nile, there is only so much water that can be taken out of the river according to an international agreement. That is why it is critical in areas like the Eastern Desert to identify and use 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," said Sturchio. "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."
-end-


University of Delaware

Related Groundwater Articles:

Majority of groundwater stores resilient to climate change
Fewer of the world's large aquifers are depleting than previously estimated, according to a new study by the University of Sussex and UCL.
Monitoring groundwater changes more precisely
A new method could help to track groundwater changes better than before.
Cause of abnormal groundwater rise after large earthquake
Abnormal rises in groundwater levels after large earthquakes has been observed all over the world, but the cause has remained unknown due to a lack of comparative data before & after earthquakes.
Shrub encroachment on grasslands can increase groundwater recharge
A new study led by Adam Schreiner-McGraw, a postdoctoral hydrology researcher at the University of California, Riverside, modeled shrub encroachment on a sloping landscape and reached a startling conclusion: Shrub encroachment on slopes can increase the amount of water that goes into groundwater storage.
River-groundwater hot spot for arsenic
Naturally occurring groundwater arsenic contamination is a problem of global significance, particularly in South and Southeast Asian aquifers.
Groundwater, a threatened resource requiring sustainable management
The WEARE group at the University of Cordoba analyzed a case of aquifer recovery and concluded that supervision, governance and use of water for high value crops are some of the keys to guaranteeing sustainability of these reserves
Co-occurring contaminants may increase NC groundwater risks
Eighty-four percent of the wells sampled in the Kings Mountain Belt and the Charlotte and Milton Belts of the Piedmont region of North Carolina contained concentrations of vanadium and hexavalent chromium that exceeded health recommendations from the North Carolina Department of Health and Human Services.
Fresh groundwater flow important for coastal ecosystems
Groundwater is the largest source of freshwater, one of the world's most precious natural resources and vital for crops and drinking water.
Natural contaminant threat to drinking water from groundwater
Climate change and urbanisation are set to threaten groundwater drinking water quality, new research from UNSW Sydney shows.
Switching to solar and wind will reduce groundwater use
IIASA researchers explored optimal pathways for managing groundwater and hydropower trade-offs for different water availability conditions as solar and wind energy start to play a more prominent role in the state of California.
More Groundwater News and Groundwater Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Debbie Millman: Designing Our Lives
From prehistoric cave art to today's social media feeds, to design is to be human. This hour, designer Debbie Millman guides us through a world made and remade–and helps us design our own paths.
Now Playing: Science for the People

#574 State of the Heart
This week we focus on heart disease, heart failure, what blood pressure is and why it's bad when it's high. Host Rachelle Saunders talks with physician, clinical researcher, and writer Haider Warraich about his book "State of the Heart: Exploring the History, Science, and Future of Cardiac Disease" and the ails of our hearts.
Now Playing: Radiolab

Insomnia Line
Coronasomnia is a not-so-surprising side-effect of the global pandemic. More and more of us are having trouble falling asleep. We wanted to find a way to get inside that nighttime world, to see why people are awake and what they are thinking about. So what'd Radiolab decide to do?  Open up the phone lines and talk to you. We created an insomnia hotline and on this week's experimental episode, we stayed up all night, taking hundreds of calls, spilling secrets, and at long last, watching the sunrise peek through.   This episode was produced by Lulu Miller with Rachael Cusick, Tracie Hunte, Tobin Low, Sarah Qari, Molly Webster, Pat Walters, Shima Oliaee, and Jonny Moens. Want more Radiolab in your life? Sign up for our newsletter! We share our latest favorites: articles, tv shows, funny Youtube videos, chocolate chip cookie recipes, and more. Support Radiolab by becoming a member today at Radiolab.org/donate.