Flag Basins

Flag Basins

G@GPS will initially target emblematic aquifers “flag basins” in most continents, but will increase the number of basins targeted as new collaborations and research projects are developed. The flag basins contain vast groundwater resources, and it is estimated that tens (if not 100s) of millions of people rely on them either directly or indirectly. Uncontrolled groundwater extraction in some of those aquifers has caused irreversible depletion. Understanding the recharge history of these aquifers will provide solid scientific data that are essential for modellers to predict future impacts, and hence for water managers who rely on such predictions. The flag basins include:


The most important water resource in the whole desert and semi-desert area of North Western Sahara is the North West Sahara Aquifer System (NWSAS), which covers an area of over 1 million Km2 and shared between Algeria, Libya and Tunisia. Learn more here.


In North America we will target the High Plains Aquifer (HPA), with a surface of ~450,000 km2 that spans all along the Midwest of the USA. The HPA is the most intensively used groundwater resource in the U.S., producing almost twice the volume of water than any other U.S. aquifer. Learn more here

In South America we will target the Guaraní Aquifer System (GAS), this constitutes one of the world’s most important fresh groundwater reservoirs with an area of 1,200,000 km2 and water volumes of ~40,000 km3. Learn more here.


The North China Plains Aquifer (NCPA) with a surface of ~120,000 km2 supports an enormous exploitation of groundwater for grain production and farming. The NCP contains 11% of China’s population and 14% of its arable land, and produces 14% and 13% of the nation’s gross domestic industrial and agricultural products, respectively. Learn more here.


The Baltic Artesian Basin (BAB) with a surface of ~480,000 km2 is one of the largest artesian basins in Europe. It fully covers the territory of Latvia, Lithuania and Estonia, parts of Poland, Russia, Belarus as well as a large area of the Baltic sea, including the island of Gotland. Learn more here.  


Two different basins have been selected, the Great Artesian Basin (GAB) and the coastal Sydney Basin aquifers. The GAB has been extensively studied and has been the benchmark were the most important age tracer studies in the last ~30 years have been initially tested (36Cl/Cl, 81Kr, 129I and 4He). Learn more here.

 The Sydney basin aquifers (SBAs) constitute a number of separate aquifers but within the same geological units, covering a surface of approximately 17,000 km2 (Cendón et al., 2009). Groundwater in the region supports irrigation and has been identified as emergency water supply for the Sydney area. Learn more here.