Nubian Sandstone Aquifer System
Encyclopedia
The Nubian Sandstone Aquifer System (NSAS) is the world’s largest known fossil water
aquifer
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
. NSAS covers a land area spanning just over two million km2, including north-western Sudan
, north-eastern Chad
, south-eastern Libya
, and most of Egypt
. Containing an estimated 150,000 km3 of groundwater
, the significance of the NSAS as a potential water resource
for future development programs in these countries is extraordinary. Recently the Great Man-made River Project (GMMR)
in Libya began extracting substantial amounts of water from this aquifer, removing an estimated 2.37 km3 per year. This system is primarily used to supply water in the Al Khufrah Oasis.
aquifer situated between the Toshka and Abu Simbel
areas of Egypt underwent 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 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.
sandstone
with great shale
and clay intercalation
, having a thickness that ranges between 140-230 meters. Groundwater type varies from fresh to slightly brackish (salinity
ranges from 240-1300 ppm). The ion
dominance ordering shows that sodium
cation is most commonly predominating over calcium
and magnesium
- whereas chloride
is predominant over sulfate
and bicarbonate
. 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
and dissolution
processes of gypsiferous shales and clay, in addition to a lengthy duration of water residence.
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
(UNDP)/Global Environment Facility
(GEF
), IAEA, United Nations Educational, Scientific and Cultural Organization (UNESCO
) 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.
Fossil water
Fossil water or paleowater is groundwater that has remained sealed in an aquifer for a long period of time. Water can rest underground in "fossil aquifers" for thousands or even millions of years...
aquifer
Aquifer
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...
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
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
. NSAS covers a land area spanning just over two million km2, including north-western Sudan
Sudan
Sudan , officially the Republic of the Sudan , is a country in North Africa, sometimes considered part of the Middle East politically. It is bordered by Egypt to the north, the Red Sea to the northeast, Eritrea and Ethiopia to the east, South Sudan to the south, the Central African Republic to the...
, north-eastern Chad
Chad
Chad , officially known as the Republic of Chad, is a landlocked country in Central Africa. It is bordered by Libya to the north, Sudan to the east, the Central African Republic to the south, Cameroon and Nigeria to the southwest, and Niger to the west...
, south-eastern Libya
Libya
Libya is an African country in the Maghreb region of North Africa bordered by the Mediterranean Sea to the north, Egypt to the east, Sudan to the southeast, Chad and Niger to the south, and Algeria and Tunisia to the west....
, and most of Egypt
Egypt
Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...
. Containing an estimated 150,000 km3 of groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
, the significance of the NSAS as a potential water resource
Water resources
Water resources are sources of water that are useful or potentially useful. Uses of water include agricultural, industrial, household, recreational and environmental activities. Virtually all of these human uses require fresh water....
for future development programs in these countries is extraordinary. Recently the Great Man-made River Project (GMMR)
Great Manmade River
The Great Man-Made River is a network of pipes that supplies water from the Sahara Desert in Libya, from the Nubian Sandstone Aquifer System fossil aquifer. It is the world's largest irrigation project....
in Libya began extracting substantial amounts of water from this aquifer, removing an estimated 2.37 km3 per year. This system is primarily used to supply water in the Al Khufrah Oasis.
Characteristics
Since 2001, the Nubian SandstoneNubian Sandstone
Nubian Sandstone refers to a variety of sedimentary rocks deposited on the Precambrian Basement in the eastern Sahara, north-east Africa and Arabia. It consist of continental sandstones with thin beds of marine limestones, and marls...
aquifer situated between the Toshka and Abu Simbel
Abu Simbel
Abu Simbel temples refers to two massive rock temples in Abu Simbel in Nubia, southern Egypt on the western bank of Lake Nasser about 230 km southwest of Aswan...
areas of Egypt underwent intensive drilling and development as part of a land reclamation
Land reclamation
Land reclamation, usually known as reclamation, is the process to create new land from sea or riverbeds. The land reclaimed is known as reclamation ground or landfill.- Habitation :...
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 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 ferruginousFerruginous
Ferruginous can refer to:* Iron oxide* Ferruginous bodies* Ferruginous Hawk* Ferruginous Duck...
sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
with great shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
and clay intercalation
Intercalation
Intercalation is the insertion of a leap day, week or month into some calendar years to make the calendar follow the seasons or moon phases. Lunisolar calendars may require intercalations of both days and months.- Solar calendars :...
, having a thickness that ranges between 140-230 meters. Groundwater type varies from fresh to slightly brackish (salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
ranges from 240-1300 ppm). The ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
dominance ordering shows that sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
cation is most commonly predominating over calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
and magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
- whereas chloride
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...
is predominant over sulfate
Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
and bicarbonate
Bicarbonate
In inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid...
. The groundwater is of meteoric origin
Meteoric water
Meteoric water is a hydrologic term of long standing for water in the ground which originates from precipitation. This includes water from lakes, rivers, and icemelts, which all originate from precipitation indirectly.- Overview :...
(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 (chemical science)
Leaching is the process of extracting minerals from a solid by dissolving them in a liquid, either in nature or through an industrial process. In the chemical processing industry, leaching has a variety of commercial applications, including separation of metal from ore using acid, and sugar from...
and dissolution
Solvation
Solvation, also sometimes called dissolution, is the process of attraction and association of molecules of a solvent with molecules or ions of a solute...
processes of gypsiferous shales and clay, in addition to a lengthy duration of water residence.
International development projects
Since 2006, the International Atomic Energy AgencyInternational Atomic Energy Agency
The International Atomic Energy Agency is an international organization that seeks to promote the peaceful use of nuclear energy, and to inhibit its use for any military purpose, including nuclear weapons. The IAEA was established as an autonomous organization on 29 July 1957...
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
United Nations Development Programme
The United Nations Development Programme is the United Nations' global development network. It advocates for change and connects countries to knowledge, experience and resources to help people build a better life. UNDP operates in 177 countries, working with nations on their own solutions to...
(UNDP)/Global Environment Facility
Global Environment Facility
The Global Environment Facility unites 182 member governments — in partnership with international institutions, nongovernmental organizations, and the private sector — to address global environmental issues....
(GEF
Global Environment Facility
The Global Environment Facility unites 182 member governments — in partnership with international institutions, nongovernmental organizations, and the private sector — to address global environmental issues....
), IAEA, United Nations Educational, Scientific and Cultural Organization (UNESCO
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations...
) 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.