Clear Waters Mercosur's Underground Treasure

By Marcela Valente and - - Reprint | | Print |

BUENOS AIRES, Apr 5 2010 (IPS) - The Guaraní Aquifer remains unpolluted and an essential reserve for an increasingly thirsty world, according to a detailed report from the four countries under which it lies. Invisible underneath a vast area of Argentina, Brazil, Paraguay and Uruguay, the Guaraní Aquifer is one of the world's largest reserves of freshwater. Despite supplying water to millions of people, it is not contaminated and it is not overexploited.

“The general health of the aquifer is good, but it is essential to take care of the areas where it is recharged” in order to prevent pollution from agrochemicals or waste from human settlements, Jorge Santa Cruz, an Argentine expert in natural sciences with a focus on geology, told Tierramérica.

Santa Cruz, professor at the University of Buenos Aires, served from 2003 to 2009 as the technical coordinator of the Project for the Environmental Protection and Sustainable Development of the Guaraní Aquifer System, under the four countries that sit above the reserve and which make up Mercosur (Southern Common Market).

The governments of the bloc pledged to maintain care for the aquifer and to continue joint efforts for better management, stated Uruguayan officials in late December in Montevideo when they presented the results of the study financed by the Global Environment Facility, administered by the World Bank.

The Mercosur Parliament took the first step by recommending to the bloc's Common Market Council to create a regional institute to research subterranean waters and environmental protection, financed by the independent Structural Convergence Fund representing the four member countries.

Santa Cruz pointed out that 97 percent of the planet's water is salty. Of the remaining three percent that is freshwater, 70 percent is found in glaciers and the polar caps, 29 percent is underground, and one percent is rivers, streams and lakes.

“Two billion people rely daily on subterranean water, as does most irrigated farmland and countless industries around the world,” but in general the concern is centered on the water resources that are visible, commented the expert.

The Guaraní is one of the world's largest aquifers. It covers 1.2 million square kilometers in the South American southeast, between 12 and 35 degrees latitude south, and 47 and 65 degrees longitude west, according to official data.

The permanent volume of water is estimated at 45,000 cubic kilometers, with 200 cubic kilometers recharged per year. In some places it extends towards the earth's surface, at just 50 meters underground, and in others it is 1,800 meters deep.

Brazil holds the largest portion of the aquifer, with 840,000 square kilometers, followed by Argentina, with 225,500 sq. km., Paraguay with 72,000, and Uruguay with 58,500.

The aquifer's water becomes salty in some areas, and in others can have arsenic or fluoride, and is not potable, but can be used for other purposes, such as energy production.

“The aquifer is excellent for urban water supply, but it must be well managed and care must be taken where it nears the earth's surface,” said Uruguayan hydrologist Danilo Antón, who proposed the name Guaraní and worked on the project.

The reserve is fed by rivers and streams, and by rainfall in the areas where it is nearest the surface, which is also where contaminants can filter in, he explained to Tierramérica.

The experts also noted that Brazil is the member that makes most use of the aquifer for potable water, with thousands of wells for about 500 cities. The largest that uses the aquifer as its sole supply of water is Ribeirão Preto, home to one million people.

There are some 200 wells in Paraguay to supply rural populations and for agricultural use. In Uruguay, there are 135, many of which are found at hot spring resorts because the water temperature is warmer than 40 degrees Celsius.

The issue on which the experts are not in agreement is the geothermic exploitation of the waters, such as in the thermal areas of northwestern Uruguay, or other sites where aquifer water temperatures reach 65 degrees.

Antón believes that for such use to be profitable, the temperature would have to be higher. But Santa Cruz maintains that it could be used for smaller local enterprise, such as meatpacking plants, poultry or fish farming and plant nurseries.

The ideal, according to Santa Cruz, “is to seek alternative uses for the aquifer, in addition to potable water or thermal spas.”

The risk of contamination could come from mostly urban zones, due to sewage tanks and industries.

Antón pointed to the situation of rural areas in Paraguay. “The excess of fertilizers or insecticides where the aquifer comes to the surface could be a threat because the aquifer is very porous.”

But he also sees the aquifer as being “underutilized.” With powerful extraction pumps in some areas, 200,000 liters per hour could be obtained, compared to 10,000 currently.

With greater exploitation, there is greater risk that extraction could surpass the aquifer's recharging capacity – as occurs in the U.S. aquifer Ogallala, where “irrational use” could result in an end to its productive use in a few decades, Antón said.

The Guaraní is “an extraordinary resource… and much more known about it” than a few years ago, he said. But some mysteries remain that could not be solved by the study, so the idea is to continue the research – but now it is up to each of the Mercosur countries.