The Nubian Sandstone Aquifer System (NSAS) is the world's largest known
fossil water
Fossil water or paleowater is an ancient body of water that has been contained in some undisturbed space, typically groundwater in an aquifer, for millennia. Other types of fossil water can include subglacial lakes, such as Antarctica's Lake Vos ...
aquifer
An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials ( gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characteris ...
system. It is located underground in the Eastern end of the
Sahara desert and spans the political boundaries of four countries in north-eastern
Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
. NSAS covers a land area spanning just over two million km
2, including north-western
Sudan, north-eastern
Chad, south-eastern
Libya
Libya (; ar, ليبيا, Lībiyā), officially the State of Libya ( ar, دولة ليبيا, Dawlat Lībiyā), is a country in the Maghreb region in North Africa. It is bordered by the Mediterranean Sea to the north, Egypt to the east, Suda ...
, and most of
Egypt
Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Medit ...
. Containing an estimated 150,000 km
3 of
groundwater
Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidated ...
, the significance of the NSAS as a potential
water resource
Water resources are natural resources of water that are potentially useful for humans, for example as a source of drinking water supply or irrigation water. 97% of the water on the Earth is salt water and only three percent is fresh water; slightl ...
for future development programs in these countries is extraordinary. The
Great Man-Made River (GMMR) project in Libya makes use of the system, extracting substantial amounts of water from this aquifer, removing an estimated 2.4 km
3 of fresh water for consumption and agriculture per year.
Characteristics
Since 2001, the
Nubian Sandstone aquifer situated between the
Toshka and
Abu Simbel
Abu Simbel is a historic site comprising two massive rock-cut temples in the village of Abu Simbel ( ar, أبو سمبل), Aswan Governorate, Upper Egypt, near the border with Sudan. It is situated on the western bank of Lake Nasser, about ...
areas of Egypt has undergone intensive drilling and development as part of a
land reclamation project. Drilling information was used to conduct a variety of studies regarding the hydrogeological setting of the area's aquifer. Results indicated that
lithological characteristics and
tectonic
Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents ...
settings are having a substantial effect on groundwater flow patterns and the area's overall aquifer potentiality, which is considered relatively low when compared to neighboring areas in eastern
Oweinat or
Dakhla.
Geology
The aquifer is largely composed of hard
ferruginous
The adjective ferruginous may mean:
* Containing iron, applied to water, oil, and other non-metals
* Having rust on the surface
* With the rust (color)
See also
* Ferrous, containing iron (for metals and alloys) or iron(II) cations
* Ferric, cont ...
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates ...
with great
shale and clay
intercalation, having a thickness that ranges between 140 and 230 meters. Groundwater type varies from fresh to slightly brackish (
salinity ranges from 240 to 1300
ppm). The
ion
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...
dominance ordering shows that
sodium
Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable ...
cation is most commonly predominating over
calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...
and
magnesium
Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...
– whereas
chloride
The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the element chlorine (a halogen) gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride sa ...
is predominant over
sulfate
The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...
and
bicarbonate
In inorganic chemistry, bicarbonate (IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with the chemical formula .
Bicarbonate serves a crucial biochem ...
. The groundwater is of
meteoric origin (the term meteoric water refers to water that originated as precipitation; most groundwater is meteoric in origin). High concentrations of sodium, chloride, and sulfates reflect the
leaching
Leaching is the loss or extraction of certain materials from a carrier into a liquid (usually, but not always a solvent). and may refer to:
* Leaching (agriculture), the loss of water-soluble plant nutrients from the soil; or applying a small amou ...
and
dissolution
Dissolution may refer to:
Arts and entertainment Books
* ''Dissolution'' (''Forgotten Realms'' novel), a 2002 fantasy novel by Richard Lee Byers
* ''Dissolution'' (Sansom novel), a 2003 historical novel by C. J. Sansom Music
* Dissolution, in mu ...
processes of
gypsiferous shales and clay, in addition to a lengthy duration of water residence.
International development projects
Since 2006, the
International Atomic Energy Agency has been working in cooperation with the four NSAS countries to help increase understanding of the aquifer's complexities through the IAEA-UNDP-GEF Nubian Project.
Project partners include the
United Nations Development Programme
The United Nations Development Programme (UNDP)french: Programme des Nations unies pour le développement, PNUD is a United Nations agency tasked with helping countries eliminate poverty and achieve sustainable economic growth and human dev ...
(
UNDP
The United Nations Development Programme (UNDP)french: Programme des Nations unies pour le développement, PNUD is a United Nations agency tasked with helping countries eliminate poverty and achieve sustainable economic growth and human dev ...
)/
Global Environment Facility
The Global Environment Facility (GEF) is a multilateral environmental fund that provides grants and blended finance for projects related to biodiversity, climate change, international waters, land degradation, persistent organic pollutants (PO ...
(
GEF
Gef ( ), also referred to as the Talking Mongoose or the Dalby Spook, was the name given to an allegedly talking mongoose which was claimed to inhabit a farmhouse owned by the Irving family. The Irvings' farm was located at Cashen's Gap near ...
), IAEA,
(
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations (UN) aimed at promoting world peace and security through international cooperation in education, arts, sciences and culture. It ...
) and government representatives from the NSAS countries. The project's long-term goal is establishing rational and equitable management of the NSAS as a productive way of advancing socio-economic development in the region and protecting biodiversity and land resources.
See also
*
Lake Ptolemy
*
African humid period
The African humid period (AHP) (also known by other names) is a climate period in Africa during the late Pleistocene and Holocene geologic epochs, when northern Africa was wetter than today. The covering of much of the Sahara desert by grasses, ...
References
Bibliography
Essay and Maps: Groundwater Resources of the Nubian Aquifer System* Dahab, K.A., El Sayed, E.A. ''Study of Hydrogeological Conditions of the Nubian Sandstone Aguifer in the Area Between Abu Simbel & Toschka, Western Desert, Egypt''. American Geophysical Union, Spring 2001
{{coord missing, Sudan
Aquifers
Aquifers of Africa
Springs of Africa
Sahara
Geography of Libya
Geology of Libya
Springs of Libya
Springs of Chad
Springs of Egypt
Springs of Sudan