Groundwater in Brazil is being overexploited for various purposes. The problem is so severe that it is compromising the flow of several Brazilian rivers, according to a study revealing that more than half of these watercourses are experiencing a reduction in their flow due to the transfer of water to the aquifers.
Brazil is a country with a vast hydrographic network, part of which depends on the Amazon basin, although there is a significant percentage that is not directly related to it and persists thanks to different types of water contributions.
## Rivers at Risk and Exploited Aquifers
More than half of Brazilian rivers are facing risks of decreased flow due to water percolation into underground aquifers. This conclusion emerged from the analysis of 17,972 wells nationwide. In 55.4% of cases, water levels were below the surface of the nearest rivers.
This difference in water levels creates a gradient favoring the percolation of water from rivers into the subsurface, which can turn these watercourses into flow losers.
This study, conducted by researchers from Brazil and abroad, was published in the scientific journal Nature Communications.
In the case of the São Francisco basin, 61% of the analyzed rivers showed a potential loss of water flow to the aquifer, a result attributed to the intensive use of groundwater, mainly for irrigation.
## The Rio Verde and the Water Security of the Region
The situation is even worse in the Rio Verde Grande basin, a tributary of the São Francisco, which extends through northern Minas Gerais and southwestern Bahía. In this case, the potential loss of flow affects 74% of the rivers.
A significant impact factor is the indiscriminate drilling of wells for agricultural irrigation or private consumption. A study published in 2021 by Ricardo Hirata and collaborators showed that at that time, there were nearly 2.5 million tubular wells in Brazil, with an illegal percentage exceeding 88%, lacking permission or registration for pumping.
The volume of pumped water, around 17,600 million cubic meters per year, would be sufficient to serve the entire Brazilian population, but less than 20% of the population benefits from it.
In addition to seriously compromising river flow, affecting the availability of groundwater for human consumption, aquatic ecosystems, and the landscape itself, excessive groundwater use can cause land subsidence, sinking, and even surface collapse.
“This scenario has already been observed in India and California, and Brazil may face similar problems if proper planning and control are not implemented. This warning is even more relevant given projections pointing to over a 50% expansion of irrigated areas in the country over the next 20 years, further straining surface and groundwater resources,” emphasizes the researcher.
## Where Does the Amazon River Originate?
The Amazon River originates in the Andes, in the Mismi snowfield in Arequipa, Peru, and extends for almost 7000 kilometers until it flows into the Atlantic Ocean, according to a document from the National Institute of Amazonian Research (INPA) of the Brazilian government.
This river system discharges over 6700 cubic kilometers of water into the ocean annually, representing 70% of Latin America’s freshwater discharge and approximately 20% of the global discharge, according to the Amazon Project: Regional Action on Water Resources, created by the Amazon Cooperation Treaty Organization (ACTO).
## Sharing the Amazon Basin
The Amazon Basin is shared among eight countries: Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, Suriname, and Venezuela. These countries have prioritized regional integration through development policies, establishing on July 3, 1978, the Amazon Cooperation Treaty, which gave rise to the Amazon Cooperation Treaty Organization.
*Cover photo: Marcio Di Pietro*
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