Amazon River
River found under Amazon

An underground river, discovered by Brazilian researchers as flowing 13,000 feet below the Amazon, is not a river as the conventional meaning suggests.

Last week, a study on the river was presented to a Brazilian science meeting, and since then it has grabbed headlines.

Scientists Brazil's National Observatory have now confirmed that the water was moving, not flowing, through porous rock at speeds that were measured in centimeter, or inches, each year, BBC News reported.

The subterranean water flow is reportedly as long as the Amazon River and up to hundred times wider. Its existence was deduced by using data from boreholes spread across the Amazon region.

According to Valiya Hamza who led the research, the information about the underground flow originated from the 241 inactive oil wells that were drilled by the Brazilian oil company Petrobras in the 1970s. The company provided the researchers thermal information, which allowed them to identify the movement of water 13,100 feet below the Amazon River.

Hamza told BBC News that the subversive water flow, which has been named after him as Rio Hamza, was not a river in the conventional sense. We have used the term 'river' in a more generic sense than the popular notion, Hamza said.

Rio Hamza is the flow of groundwater through the deep sedimentary layers. Thus, the Amazon rainforest has two separate drainage systems, the other one being the surface drainage through the Amazon.

Although both the Amazon and Hamza share the same length of 6,000 kilometers, and flow from west to east, they differ in width. The Amazon ranges from 1 kilometer to 100 kilometers in width, while Hamza ranges from 200 kilometers to 400 kilometers. However, the Amazon flows much faster than the Hamza.

According to the research, titled Indications of an Underground River beneath the Amazon River: Inferences from Results of Geothermal Studies, the starting point of the underground river is the Acre region under the Andes. It reaches the sea at Foz do Amazons, flowing through basins of rivers Solimões, Amazon and Marajo.

Computer simulations show that the groundwater flow is largely vertical to about 2,000 feet deep. However, at greater depths, it changes direction and becomes horizontal.

Compared to the Amazon, which has a flow rate of 1,30,000 cubic meters per second, the Hamza is estimated at 3,900 cubic meters per second. But even then, it is pretty significant. If it was on the surface it would be bigger than the São Francisco river, says Hamza.

It empties in the Atlantic Ocean, deep under the surface and may also be responsible for the low salinity around the mouth of the Amazon River, researchers said.

Though the studies are in the early stages, Hamza expects to confirm the subterranean flow by the end of 2014.