Posted on behalf of Lee Sweetlove
Scientists have claimed that the Amazon basin has a second huge river some four kilometres beneath the more famous river on the surface, many news outlets report. The river has been named the Rio Hamza, after the head of the team that led the research from the Department of Geophysics at Brazil’s National Observatory.
Valiya Hamza and his team predicted the presence of the sub-surface river based on temperature measurements taken in 241 abandoned deep wells drilled in the region by the Brazilian oil company, Petrobras. The findings were reported last week in Rio de Janeiro at the International Congress of the Brazilian Geophysical Society.
The team constructed a mathematical model of underground water flow using the principle that water flowing through rocks causes anomalies in the dispersal of geothermal heat. Their model suggests that groundwater in the Amazon floodplain travels vertically downwards for about 2 km, but then gradually begins to flow horizontally as it reaches the impermeable basal layer 4 km down.
Although the amount of water in the underground river is much less than in the Amazon on the surface, Hamza reckons that the water flow may account for the relatively low salinity of the waters around the mouth of the Amazon.
However, calling the water flow an underground river is premature, says hydrogeologist Larry Murdoch of Clemson University in South Carolina. “This sounds like an interesting study that could contribute to the understanding of groundwater in the Amazon Basin,” he says. But “it would be worthwhile trying to explain the temperature measurements in the context of a conventional groundwater flow system before inferring the existence of a new underground river”.
As Hamza himself makes clear, this is not a river in the conventional sense. “This is water flowing through porous rock, mainly sandstone and under that, conglomerate,” he says. Unlike a true river, this underground water flow has “no fixed boundary”.