2.1 Margat’s Inventory of Mega Aquifer Systems
In his world-wide inventory of large aquifer systems, Margat (2006; 2008) identified thirty-seven large aquifer systems and classified them as ‘les très grands systèmes aquifères du monde’ (the world’s very large aquifer systems). Later, Margat and Van der Gun (2013) introduced the term ‘mega aquifer systems’ for this category of very large aquifer systems. Figure 9 shows the location of these mega aquifer systems (projected on WHYMAP’s hydrogeological world map), while Table 4 lists their names and approximate size.
Figure 9 – The world’s mega aquifer systems (after Margat, 2008; WHYMAP, 2008). View a larger version of this figure.
Table 4 – The Earth’s mega aquifer systems (after Margat and Van der Gun, 2013, modified).
| # | Aquifer System | Area (× 1 000 km2) |
Maximum thickness (m) | Countries involved (ISO-3 alpha code) |
| AFRICA | ||||
| 1 | Nubian Aquifer System (NAS) (Nubian and Post-Nubian Systems) |
2 199 | 3 500 | EGY, LBY, SDN, TCD |
| 2 | North-Western Sahara Aquifer System | 1 019 | 1 600 | DZA, LBY, TUN |
| 3 | Murzuk-Djado Basin | 450 | 2 500 | DZA, LBY, NER |
| 4 | Taoudeni-Tanezrouft Basin | 2 000 | 4 000 | DZA, MRT, MLI |
| 5 | Senegalo-Mauritanian Basin | 300 | 500 | MRT, SEN, GMB, GNB |
| 6 | Iullemeden-Irhazer Aquifer System | 635 | 1 500 | NER, DZA, MLI, NGA |
| 7 | Lake Chad Basin | 1 917 | 7 000 | NER, NGA, TCD, CMR, CAF |
| 8 | Sudd Basin (Umm Ruwaba Aquifer) | 365 | 3 000 | SSD, SDN, ETH |
| 9 | Ogaden-Juba Basin | ~1 000 | 12 000 | ETH, SOM, KEN |
| 10 | Congo Basin | ~1450 | 3 500 | COG, COD, AGO, RAF, GAB |
| 11 | Cuvelai-Upper Zambezi Basin (Upper Kalahari) | ~900 | AGO, BWA, NAM, ZMB, ZWE | |
| 12 | Stampriet-Kalahari Basin (Lower Kalahari) | ~350 | ZAF, BWA, NAM | |
| 13 | Karoo Basin | 600 | 7 000 | ZAF |
| NORTH AMERICA | ||||
| 14 | Northern Great Plains Aquifer System | 770 | 2 000 | CAN, USA |
| 15 | Cambrian-Ordovician Aquifer System | 250 | 1 000 | USA |
| 16 | California’s Central Valley Aquifer System | 52 | 600 | USA |
| 17 | High Plains Aquifer (Ogallala) | 450 | 150 | USA |
| 18 | Atlantic and Gulf Coastal Aquifer System | 1 150 | 12 000 | USA, MEX |
| SOUTH AMERICA | ||||
| 19 | Amazon Basin | 2000 | 7 000 | BRA, COL, PER, BOL |
| 20 | Maranhão Basin (ParnaÍba Basin) | 700 | 3 000 | BRA |
| 21 | Guarani Basin (Paraná Basin) | 1 195 | 800 | BRA, ARG, PRY, URY |
| ASIA | ||||
| 22 | Arabian Aquifer System | > 1 485 | 6 500 | SAU, JOR, KWT, BHR, QTR |
| 23 | Indus Basin | ~ 320 | 300 | PAK, IND |
| 24 | Ganges-Brahmaputra Basin | ~ 600 | 600 | IND, NPL, BGD |
| 25 | West Siberian Basin | 3 200 | 6 000 | RUS |
| 26 | Tunguss Basin | 1 000 | 4 000 | RUS |
| 27 | Angara-Lena Basin | 600 | 3 000 | RUS |
| 28 | Yakut Basin | 720 | 1 200 | RUS |
| 29 | Greater North China Plain Aquifer System (Huang Huai Hai Plain) | 320 | 600 | CHN |
| 30 | Song-Liao Plain (NE China Plain) | 311 | 300 | CHN |
| 31 | Tarim Basin | 520 | 1 200 | CHN |
| EUROPE | ||||
| 32 | Paris Basin | 190 | 3 200 | FRA |
| 33 | Russian Platform Basins | ~ 3 100 | 20 000 | RUS, EST, LVA, LTU, BLR, UKR |
| 34 | North Caucasus Basin | 230 | 10 000 | RUS |
| 35 | Pechora Basin | 350 | 3 000 | RUS |
| AUSTRALIA | ||||
| 36 | Great Artesian Basin | 1 700 | 3 000 | AUS |
| 37 | Canning Basin | 430 | 1 000 | AUS |
The names of four of these systems require some clarification. First, in publications system number 1 is alternately called ‘Nubian Aquifer System’ and ‘Nubian Sandstones Aquifer System’, often indiscriminately. Here, the name ‘Nubian Aquifer System’ is used to indicate the total system extending northward to the Mediterranean Sea, including both the Nubian Sandstones and the Post-Nubian sediments which overly and confine the northward dipping Nubian Sandstones to the north of roughly 26°N. Second, system number 18, originally called the ‘Atlantic and Gulf Coastal Plains Aquifer System’, has been renamed to ‘Atlantic and Gulf Coastal Aquifer System’, to better represent all included aquifer units. Third, system number 21 is renamed here to ‘Guarani Basin’, because the name ‘Guarani Aquifer System’ – used by Margat and Van der Gun (2013) – refers in most publications only to the largely confined Guarani aquifer, without including other aquifers in the basin such as those present in the overlying Serra Geral Basalts and Bauru-Caiuá sediments. The Guaraní Basin is also known as Paraná Basin (Rebouças,1999; Feitosa et al, 2016). Fourth, publications alternately use the name ‘North China Plain’ to indicate either the Huang Huai Hai Plain (320,000 km2 in extent) or – in most cases – only the northern part of this area (Hai Plain, 136,000 km2). Therefore, the name ‘Greater North China Plain’ is used here to indicate mega aquifer system number 29, as an English equivalent of the name Huang Huai Hai Plain.