Major aquifers

This entry lists the major (mega) aquifer system(s) that underlie a country, keeping in mind that many of these mega aquifers are so large that they extend under multiple countries. More than 30% of freshwater is held in underground aquifers. There is great variation in the size of such aquifers, but a limited number of very large aquifer systems contain a majority of the World’s groundwater volume in storage.

• Algeria

  Lullemeden-Irhazer Aquifer System, Murzuk-Djado Basin, North Western Sahara Aquifer, Taoudeni-Tanezrouft Basin

• Angola

  Congo Basin, Upper Kalahari-Cuvelai-Upper Zambezi Basin

• Argentina

  Guarani Aquifer System

• Australia

  Great Artesian Basin, Canning Basin

• Bahrain

  Arabian Aquifer System

• Bangladesh

  Indus-Ganges-Brahmaputra Basin

• Bolivia

  Amazon Basin

• Botswana

  Lower Kalahari-Stampriet Basin, Upper Kalahari-Cuvelai-Upper Zambezi Basin

• Brazil

  Amazon Basin, Guarani Aquifer System, Maranhao Basin

• Cameroon

  Lake Chad Basin

• Canada

  Northern Great Plains Aquifer

• Central African Republic

  Congo Basin, Lake Chad Basin

• Chad

  Lake Chad Basin, Nubian Aquifer System

• China

  North China Aquifer System (Huang Huai Hai Plain), Song-Liao Plain, Tarim Basin

• Colombia

  Amazon Basin

• Congo, Democratic Republic of the

  Congo Basin

• Congo, Republic of the

  Congo Basin

• Egypt

  Nubian Aquifer System

• Ethiopia

  Ogaden-Juba Basin, Sudd Basin (Umm Ruwaba Aquifer)

• France

  Paris Basin

• Gabon

  Congo Basin

• Gambia, The

  Senegalo-Mauritanian Basin

• Guinea-Bissau

  Senegalo-Mauritanian Basin

• India

  Indus-Ganges-Brahmaputra Basin

• Iraq

  Arabian Aquifer System

• Jordan

  Arabian Aquifer System

• Kenya

  Ogaden-Juba Basin

• Kuwait

  Arabian Aquifer System

• Libya

  Nubian Aquifer System, North Western Sahara Aquifer System, Murzuk-Djado Basin

• Mali

  Lullemeden-Irhazer Basin, Taodeni-Tanezrouft Basin

• Mauritania

  Senegalo-Mauritanian Basin, Taodeni-Tanzerouft Basin

• Mexico

  Atlantic and Gulf Coastal Plains Aquifer

• Namibia

  Lower Kalahari-Stampriet Basin, Upper Kalahari-Cuvelai-Upper Zambezi Basin

• Nepal

  Indus-Ganges-Brahmaputra Basin

• Niger

  Lake Chad Basin, Lullemeden-Irhazer Basin, Murzuk-Djado Basin

• Nigeria

  Lake Chad Basin, Lullemeden-Irhazer Aquifer System

• Oman

  Arabian Aquifer System

• Pakistan

  Indus Basin

• Paraguay

  Guarani Aquifer System

• Peru

  Amazon Basin

• Qatar

  Arabian Aquifer System

• Russia

  Angara-Lena Basin, Pechora Basin, North Caucasus Basin, East European Aquifer System, West Siberian Basin, Tunguss Basin, Yakut Basin

• Saudi Arabia

  Arabian Aquifer System

• Senegal

  Senegalo-Mauritanian Basin

• Somalia

  Ogaden-Juba Basin

• South Africa

  Karoo Basin, Lower Kalahari-Stampriet Basin

• Sudan

  Nubian Aquifer System, Sudd Basin (Umm Ruwaba Aquifer)

• Tunisia

  North Western Sahara Aquifer System

• United States

  Northern Great Plains Aquifer, Cambrian-Ordovician Aquifer System, Californian Central Valley Aquifer System, Ogallala Aquifer (High Plains), Atlantic and Gulf Coastal Plains Aquifer

• Uruguay

  Guarani Aquifer System

• World

  summary statement: aquifers are underground layers of water-bearing permeable rock formations; they include alluvial formations such as unconsolidated sand and gravel aquifers, sedimentary rock formations of sandstone and karst (carbonate rocks such as limestone) aquifers, as well as volcanic aquifers, and basement aquifers (igneous and metamorphic rocks that underlie sedimentary and volcanic rock sequences); groundwater from aquifers can be extracted using a water well; The World Factbook lists 37 major aquifers across 52 countries; of these, 13 are in Africa, 10 in Asia, 5 in North America, 3 in South America, 4 in Europe, and 2 in Australia; although aquifers can vary in size, the major aquifers listed in The Factbook contain the bulk of the stored volume of groundwater; the fresh water held in these aquifers represents more than 30% of the World's fresh water; in the US, groundwater is primarily used for irrigation and globally, 70% of groundwater withdrawn is used for agriculture; groundwater also supplies almost half of all drinking water worldwide

• Zambia

  Upper Kalahari-Cuvelai-Upper Zambezi Basin

• Zimbabwe

  Upper Kalahari-Cuvelai-Upper Zambezi Basin