Recent Hydrological Droughts in Brazil and Their Impact on Hydropower Generation

Abstract

Brazil has endured the worst droughts in recorded history over the last decade, resulting in severe socioeconomic and environmental impacts. The country is heavily reliant on water resources, with 77.7% of water consumed for agriculture (irrigation and livestock), 9.7% for the industry, and 11.4% for human supply. Hydropower plants generate about 64% of all electricity consumed. The aim of this study was to improve the current state of knowledge regarding hydrological drought patterns in Brazil, hydrometeorological factors, and their effects on the country’s hydroelectric power plants. The results show that since the drought occurred in 2014/2015 over the Southeast region of Brazil, several basins were sharply impacted and remain in a critical condition until now. Following that event, other regions have experienced droughts, with critical rainfall deficit and high temperatures, causing a pronounced impact on water availability in many of the studied basins. Most of the hydropower plants end the 2020–2021 rainy season by operating at a fraction of their total capacity, and thus the country’s hydropower generation was under critical regime.

Hydrological Retrospective and Historical Drought Analysis in a Brazilian Savanna Basin

“…Overall, 294 months presented SSI values classified as drought or abnormally dry, of which 51.7% occurred in the last third of the period (1996-2018), behavior also observed in other studies of hydrological drought in Brazil [65,71,73]. Consequently, this period from 1996 to 2018 displayed the lowest number of months with SSI ≥ 0.5, only 7.9% of the total.…”

“…In 2001, a severe drought hit a large part of the Southeastern Brazilian region, resulting in a national energy crisis due to the reduction in the reservoir level of hydropower plants [72]. The drought of the last decade was one of the most severe in recent years in several basins in Brazil, causing impacts on agricultural production, hydropower generation, and over the environment [28,65,68,73]. From 2012 to 2016, 33.4 million people were affected by the droughts in Brazil, with estimated damage of BRL 104 billion (approximately USD 20 billion) [69].…”

“…From 2012 to 2016, 33.4 million people were affected by the droughts in Brazil, with estimated damage of BRL 104 billion (approximately USD 20 billion) [69]. Cuartas et al [73] and Junqueira et al [28] report that, in addition to reduced precipitation, temperature increases have intensified the drought conditions in basins located in the Brazilian savanna. Junqueira et al [33] highlight that there was a 1.3 • C increase in temperature from 2013 to 2018 in the PRB, resulting in an increase in the evapotranspiration rate from 81.4% to 88.4%.…”

Trends and Climate Elasticity of Streamflow in South-Eastern Brazil Basins

“…This may have been caused by a variety of climatological factors that led to lower rainfall and higher PET (both trends also detected in this study), such as, changes in rainfall seasonality or lack of extremely high rainfall events. In a drought indicators analysis in Brazil [61], the authors found that the last decade (2011-2021) recorded the highest recurrence of severe droughts since 1981. The authors also suggest that droughts are more intense and frequent due to the compound effect of decreased precipitation and increased in temperature in a possible global warming scenario.…”

“…The authors also suggest that droughts are more intense and frequent due to the compound effect of decreased precipitation and increased in temperature in a possible global warming scenario. The decreased precipitation and increased surface temperature result in the increased evapotranspiration and decreased soil moisture, leading to negative feedback processes that exacerbate drought events [61]. In a monthly precipitation assessment from 1961 to 2011 in Southeastern Brazil, non-significant trends were detected, but significant positive trends in mean temperature, as well as in PET for all months of that period were detected [48].…”