The Underground River Beneath The Amazon River

Add this to the long list of amazing things that is the Amazon River: Brazilian scientists have found a new river that runs underneath it!

The Rio Hamza, named after the head of the team of researchers who found the groundwater flow, appears to be as long as the Amazon river but up to hundreds of times wider.
Both the Amazon and Hamza flow from west to east and are around the same length, at 6,000km. But whereas the Amazon ranges from 1km to 100km in width, the Hamza ranges from 200km to 400km.

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Open letter about the "Hamza River"
A subjective idea was presented during the 12th International Congress of the Brazilian Geophysical Society, in Rio de Janeiro, and published in the media in August 2011: "Below the Amazon River, inside the rocks at a depth of 4,000 meters, there is probably an "underground river", 6,000 km long and 400 km wide."
Such a statement would only be criticized in an academic environment restricted to scholars. However, this scientific communication, originally restricted to the Congress, was probably sent through release to numerous scientific and non-scientific communication vehicles and took the worldwide geological community by surprise.
The release of results from a simplistic research, which used real and proven hard-data, but reached unlikely conclusions by using incorrect geological definitions, undermines the public understanding of science.
The information, brought by a research group of the Observatório Nacional (Brazilian National Observatory), traveled the world under the name "Rio Hamza" (“Hamza River”) in allusion to one of those involved in the research.
However, it is a precipitated conclusion from a doctoral thesis based on indirect data – measurements of well temperatures drilled for oil since the 1970s. In addition, the conclusion has not been evaluated by independent researchers and contains a series of language and interpretation inaccuracies, harming rooted concepts in Geosciences.
The Amazon River crosses, from west to east, successively five major
sedimentary basins, called Acre, Solimões, Amazonas, Marajó and Foz do
Amazonas. Sedimentary basin is a geological term for a usually huge depression that was filled with different kinds of sediments (sand, mud etc) from one or more sources through time.
The basins beneath the Amazon River are filled by a succession of sedimentary rock layers several thousand meters thick. If these rocks are porous, they host (ground)water, a common situation in sedimentary basins. If, besides being porous, the rocks are permeable (the pores are interconnected), the water will be able to flow, commonly with speeds measured in cm/year. The situation is also normal in sedimentary basins, like the ones crossed by the Amazon River. This is well known and has long been studied by Brazilian geologists.
One explanation accepted by the Brazilian geological science is that the "Hamza River" "discovered" by the geophysicists from the Observatório Nacional, is not a river but a possible very slow flow within an aquifer formed of porous and permeable sedimentary rocks.
Even as a figure of speech, the term "underground river" used by those researchers is absolutely incorrect for this case, since this term is used, and only with caution, in situations where water flows through caves.
The water of the “Hamza River” is not sweet - at this depth, it is over-saturated in soluble salts, i.e., brine. The continuity of the deep aquifer through 6,000 km is not proven nor there is any idea if its waters discharge to other sedimentary basins nearby.
It is a recklessness claim, as it was done in the Thesis under discussion, that the water of this aquifer would have some influence on the salinity of sea waters near the mouth of the current Amazon River. The existence of "fresh water pockets" in the Atlantic Ocean nearby is due to the huge discharge of the Amazon River whose waters invade the sea for many kilometers from its mouth.
This wrong way of publishing preliminary research results undermines the credibility of Brazilian research. In this case, the "discovery" of a fake "underground river" was boasted in a hasty and sensationalist manner.
The signatories of this open letter contest, in a responsible manner, the conclusions taken for granted, but that actually lack any technician sense in the light of the geological science that is practiced in Brazil and worldwide.
Prof. Dr. Celso Dal Ré Carneiro (UNICAMP) (Brazil)
Prof. Dr. Eduardo Salamuni (UFPR) (Brazil)
Prof. Dr. Luiz Ferreira Vaz (UNICAMP) (Brazil)
Prof. Dr. Heinrich Theodor Frank (UFRGS) (Brazil)
Apoio: Federação Brasileira de Geólogos – FEBRAGEO (Brazil)