11 July 2010

The Guaraní Aquifer - Ground Water in South America II

Despite containing some of the driest areas on earth in Peru and Northern Chile and large arid zones in the vast expanses of east of the Andes, in Patagonia and in Northeastern Brasil, South America is well endowed with water supplies. Five huge river systems – the Amazon, the streams of the Rio de la Plata estuary, the Orinoco, the Magdalena, the São Francisco – and numerous smaller ones along the western slope of the Andes and the Caribbean and Atlantic Coasts make South America a water rich continent. Unlike Asia and Africa where a large fraction of the water supply is already in use, South America has water resources hardly tapped for human uses other than transportation. Hidrovia, noted in an earlier posting, is mostly a transportation proposal

The Guaraní aquifer is one of the largest known underground water deposits. Some even think it is the largest fresh water body on earth, larger in total volume than either Lake Superior or Lake Baikal! It is estimated to contain more than 35,000 cubic kilometers of water (the estimates on the map above are at the high end of the range) in a basin that stretches from tropical Brasil south into Paraguay, Argentina, and Uruguay with a surface extent of well over a million square kilometers. At present, water from the aquifer directly supplies about 30 million people, though it is estimated that it could sustainably support the water needs of 10 times that many. Outflow from the aquifer supplies some of the water in several major rivers including the Paraná and the Uruguay. Among the major aquifers of the world it is one of the least utilized, and except locally around a few communities using the water, there is little evidence pointing to the draw down and even exhaustion of groundwater familiar in large aquifers elsewhere.

With increasing demand for water throughout the world, there will undoubtedly be increased demand for the water in the Guaraní Aquifer. The booming economy of Brasil has increased water demand for urban uses, industry, and especially for agriculture in the recent past. Much of the Brasilian population lives near the aquifer, and the immense metropolitan area of São Paulo is only a few kilometers from its edge.  As with many large aquifers, much is unknown about the quantities of water and patterns of flow below the surface. A large research project by the IAEA (International Atomic Energy Agency) is attempting to discover more about the aquifer in hopes of improving management as water demands increase. All of the countries are members of Mercosur, the Common Market of the South, and there is an effort to use it as a foundation for management of the aquifer as demands for water increase.

During the Cheney-Bush administration the United States held military exercises in Paraguay, and there was a rumor that Bush or members of its family had purchased 100,000 hectares in the northern part of the landlocked country. While there is no compelling evidence to support the contention, local critics argued that the US was engaged in military exercises in a preliminary move to claim water from the aquifer. That is probably incorrect, at least for now, but the Guaraní is likely to be a major focus in debates about the world's water in the very near future. A documentary film about it is currently in production by the Guarani Project.