Characterization of the recent (2019–2022) La Plata Basin hydrological drought from a centennial-scale perspective

Several major rivers within the La Plata Basin (LPB), the third largest basin in the world, have experienced record-low water levels between 2019 and 2022, with significant impacts for the economy of the region. This hydrological drought originated from a precipitation deficit over the headwaters of the Paraná, Paraguay, and Uruguay rivers, in response to an unusual multi-year La Niña episode. The objective of this study is to characterize the hydrological drought and quantify its unusualness by analyzing a set of indices based on daily, monthly, and annual streamflow and water levels of the main rivers of LPB, using centennial records. The results indicate that the recent hydrological drought was unprecedented in the context of the past 50 years in terms of severity and duration, featuring extreme drought conditions and duration over 25 months. The atmospheric drivers of the drought are analyzed, and future perspectives for water management are discussed.