Persistent droughts form deserts in large regions of the American continent

Prolonged droughts accompanied by fires, which experts indicate on the maps in red, orange and maroon colors to accentuate the most critical areas, have touched records in 2022 in the American continent.

The numbers show the serious situation of the water issue, according to a study of the Global Drought Observatory, which conducted a comparative analysis between 1980 and 2020.

The report makes visible how the average amounts of precipitation have gone down in the last decade, with reductions of between 30 and 90% in areas such as eastern Brazil, the coast of Venezuela and parts of Chile, Ecuador, Peru and Argentina.

In Chile, for example, the drought is such that it has set off alarms and opened discussions about contingency plans to deal with the situation and how it would impact subsistence and the agricultural and fish farming industries in the South American nation.

A study by the World Meteorological Organization (WMO) contributed to the debate on why the rains decrease, which last July indicated that the glaciers of the Andes have lost between 30 and 50% of ice since the 1980s. seen as one of the causes of droughts.

“[En Chile existe] a mega-drought that has lasted for 13 years, with certain windows of rain,” Gabriel Mancilla, director of the Water Center for Arid and Semi-arid Zones of Latin America (CAZALAC), explained to the press.

The head of this reference center estimates that the greatest impact occurs due to the intensity of the phenomenon. “The impacts are becoming more intense, mainly due to the greater demand for water (…) We have made some calculations, according to which, if we achieve an irrigation efficiency of 90%, we could reduce by a very important percentage the water deficits, by 80%, at least in Chile”.

West coast situation

In the north of the American continent, the situation is similar, and in some regions of Mexico and the west coast of the United States, triggered the alarms. The National Water Commission (Conagua) of the Aztec country decreed a “drought emergency” on July 13.

The Mexican government is keeping Monterrey under observation, the second most populous city in Mexico, which is located in the northern fringe of the country, and which has seen its water reserves reach a minimum, which has led to measures to restrict its use. .

In the United States, the National Aeronautics and Space Administration (NASA) public weeks ago images captured by its satellites to show how one of the most important reservoirs of water between Arizona and Utah, Lake Powell, has dropped drastically in the last three years.

The low level of the reservoir shows the seriousness of the situation in the western region of the US, which is facing a water crisis that has been increasing.

“Much of Washington, Oregon, northern Idaho to northwestern Montana, and southern California to parts of New Mexico were dry this week. Groundwater continues to be low and many reservoirs were still very low to near a record low,” the USDN Drought Monitor noted this week.

This observatory created in joint collaboration between The National Drought Mitigation Center at the University of Nebraska-Lincoln, the United States Department of Agriculture and the National Oceanic and Atmospheric Administration (NOAA), further warned that at the end of August “the combined storage total of the 12 main reservoirs” in the most critical region “was among the three lowest totals small since 1990”.

In the United States and Europe, the lack of rain is also accompanied by raging fires that generate another additional concern due to the lack of water to deal with the fire and the dry conditions that facilitate its proliferation, plus the increase in pollution and greenhouse gases. .

Rain gauges in areas advancing towards desertification have come to record that the rainfall deficit would be around 70%, and with it the reduction of underground aquifers continues to fall due to extraction to meet consumption needs.

“The precipitation that fell this week did little to offset the deficits that have accumulated over the past five years. Very little improvement was made on this week’s map over the areas that received precipitation,” noted the USDN Drought Monitor.

Evidence of the water crisis in the western region of the United States is also shown by the emblematic Colorado River, which along its way supplies a considerable number of cities in the central west of the country, which, like other reservoirs, has seen its flow decrease.

This year’s estimates suggest that “the prolonged drought of 22 years” has taken the once powerful flow to a capacity of 34% compared to the best times on record, with which this 2022 would drop even more from the decrease registered in 2021.

With this, both the reservoirs of Lake Powell and Lake Mead, which are fed by this tributary, are between 27% and 25% of their capacity.

The dry corridor and the running water

If problems with lack of rain and desertification are evident in the north and south, the Pacific slope in Central America also has problems that are exacerbated in the so-called Central American Dry Corridor, a strip of vulnerability that extends from the north of Nicaragua, crosses part of Honduras and El Salvador and deepens in Guatemala.

Guatemala has experienced the greatest severity with regions where the rain cycles have been disrupted, both in frequency and intensity. The report “Drought in numbers 2022, restoration for preparedness and resilience”, published in June for the World Day to Combat Desertification and Drought, carried out by the United Nations (UN), details the impacts in the region.

“The figures revealed by this study are conclusive: around 17 million people were affected by drought between 2000 and 2019 in the region, with the countries that top the list being Guatemala, Haiti, Paraguay, Honduras and El Salvador,” says the study.

For the hydrologist engineer Jaime Contreras, the Northern Triangle of Central America is a subregion that shows the impacts of climate change, not only because of the irregularity of the rains, but also because of the concentrations in one place, contrary to other areas that remain dry.

Also due to the amounts of rain accumulated in short periods, which breaks the natural cycle of infiltration, because a large part of the water that falls generates enormous currents that, by force of gravity, erode the soil and return to the sea without completing their natural cycle.

This expert who works from Central America comments to the voice of america that the main problem in the region is that the level of aquifer recharge continues to decline, if compared to the first data that began to be recorded in the 1970s.

“There are comparative studies that show that in the area of ​​San Salvador, for example, an absorption level of up to 70% at the end of the 1970s went from 30% today, because with urban development there has been lost that absorption capacity,” he explains.

This expert also considers that the preparation for the effects of climate change can no longer be postponed, while at the same time pilot projects that are already operating in some countries of the region have to be amplified to artificially recharge the aquifers.

This would be achieved by creating infrastructures that can contain sufficient amounts of rainwater and that these reserves can be gradually injected into the ground to ensure the subsistence of the underground aquifers.

Otherwise, warns the hydrologist Contreras, in the Dry Corridor of Central America, windows of intense rain could be seen, but most of the water would flow down to the sea, without completing its cycle that would guarantee the permanence of the aquifers.

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