SCIENTISTS IN Brazil believe they have discovered a giant subterranean river flowing several kilometres beneath the Amazon river.
A team of geophysicists at the country’s national observatory said an examination of 241 oil wells drilled across the Amazon region in the 1970s and 1980s indicated the presence of a river system up to 4km below the Earth’s surface. The scientists believe the river is up to 6,000km long and, like the Amazon, flows from west to east.
“Tests on water temperatures in the wells show that for the first 2,000m, water movement is vertical, going down. But then, between 2,000 and 4,000m, the movement is lateral,” says Valiya Hamza, the leader of the team that made the discovery and after whom the river has been named.
Though almost as long as the 6,110km Amazon, the underground river is up to four times as wide, stretching out to 400km in places.
Prof Hamza said the discovery means the Amazon basin has two drainage systems – the Amazon and Hamza rivers. Like the Amazon, the underground river is fed by waters from the Andes mountains to the west of Brazil.
It is formed by fresh water but because of its great depth its temperature is 30-35 degrees, significantly warmer than the tropically heated Amazon river.
With a flow rate of 130,000 cubic metres a second, the Amazon is by far the world’s biggest river and dwarfs the Hamza, which the team estimates has a flow of just 3,900 cubic metres a second. “But even then, it is pretty significant. If it was on the surface it would be bigger than the São Francisco river,” says Prof Hamza, referring to the biggest river wholly within Brazil’s borders.
It would also make the underground river bigger than Europe’s Rhine, Loire and Elbe rivers combined. If its length of 6,000km is confirmed, it would rank as the world’s fifth-longest river, just behind the Mississippi.
The team examined data from oil wells drilled in the western Amazonian state of Acre right the way across the Amazon basin to the island of Marajó at the mouth of the Amazon river itself. It plans to undertake a further two years of tests and analysis to confirm the Hamza’s existence.
Though the size of the new river was described as “fantastic” by the team, the likely existence of underground rivers is known to geophysicists. “Underground water movement is a phenomenon that occurs in diverse geological environments,” says Prof Hamza.
“For example, it appears that there is a subterranean river underneath Rome.”