Water reuse and desalination will allow aquifers to be preserved, experts say

The United Nations (UN) chose groundwater this year to commemorate World Water Day. These aquifers contain more than 95% of the planet's available freshwater, 250 times more volume than can be seen with the naked eye, according to the organization. They are essential for maintaining the ecosystem and are the only source of human supply in arid zones.

Given population and economic growth, the greatest threat to these bodies of water is overexploitation, which happens when more water is extracted than it receives in a certain period of time.

UNESCO's World Water Assessment Programme warns that almost half of the world's population is supplied with drinking water through underground sources, but that 20 per cent of these are at risk of becoming unusable. Another study published by Nature in 2019 estimates that, by 2050, between 42 and 79 percent of the world's aquifers will be compromised their resilience.

If we add to this that for the Intergovernmental Panel on Climate Change (IPCC), arid zones in Latin America are particularly vulnerable due to the intensification of droughts, then the groundwater landscape is complicated by increased demand that will demand the 707 million Latin Americans that the Economic Commission for Latin America and the Caribbean (ECLAC) expects by 2040.

Another noteworthy fact is that the average Latin American consumes 135 liters of water a day directly, but indirectly, through products and services, this index, known as the water footprint, is between 1,600 and 2,000 cubic meters per year, when the world average is 1,385. This puts considerable pressure on the region's groundwater.

Aquifers are underground rock and sand formations that store water. Depending on their permeability, they can let water pass through or retain it. These structures are an essential part of the hydrological cycle. More than 2,600 groundwater reservoirs have been identified that supply more than 500 Latin American cities. Of these, the Guaraní Aquifer stands out, which is located in the Rio de la Plata basin system in the countries of Brazil, Paraguay, Argentina and Uruguay and covers more than 1.2 million square kilometers and has an average annual discharge of 40 to 60 km3, making it the largest in this area. part of the world.

According to the Spanish Water Information System, Hispagua covers an area of approximately 850,000 km2 (9.9% of the territory) in Argentina 225,000 km2 (7.8%) in Paraguay 70,000 km2 (17.2%) and in Uruguay 45,000 km2 (25.5%).

Representatives of the Latin American Association for Desalination and Water Reuse (ALADYR), a non-governmental non-profit organization, called for sustainable groundwater management by implementing seawater desalination and reuse to reduce pressure extractivist and preserve these natural sources.

Juan Miguel Pinto, president of ALADYR, considered that “the conservation of groundwater requires, in the first instance, adequate monitoring”. According to the Global Groundwater Monitoring Network (GGMN) for 2019, of the 19 countries that only Brazil, Chile, Colombia, Costa Rica, El Salvador, Mexico, Peru and Venezuela “have a clear nationwide monitoring program published,” he said.

Pinto explained that, “after monitoring, if it is known that the aquifer is under pressure that it cannot withstand, then we must be more efficient in the use of the resource being extracted and that this is achieved through the reuse of water, which consists of treating effluents and wastewater to use them in other activities ”. Then, if this is not enough, “it is necessary to look for other supply alternatives to give the underground reservoir time to recover and, in this case, desalination of seawater and brackish wells is the best option,” he said.

He also said that, given the above-mentioned evidence on climate change and population increase, “urgent measures must be taken so that no one is left behind in access to essential products and services.” He cited the case study of water reuse from the wastewater treatment plant (WWTP) in the Chapultepec forest, the green lung of Mexico City, for being able to treat a wastewater flow of 170 liters per second and making it suitable for direct recharge of aquifers.

“The technologies are there to be leveraged and have been tested,” emphasized Pinto, who also took the opportunity to say that ALADYR has a group of experts in technologies and legislation that is available to public and private institutions to assist in the implementation of these solutions.

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