Recent extreme drought over La Plata Basin: A glimpse of the future?

JUAN ANTONIO RIVERA; MALAËKA ROBO

Berlín

Conferencia; XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG); 2023

Some of the main rivers of La Plata Basin (LPB), the third largest basin in the world, located in Southern South America, has been experiencing record low water levels between 2020 and 2022. This hydrological drought originated from meteorological drought conditions over the headwaters of Paraná and Paraguay rivers in southern Brazil, but also over much of Central Argentina and Uruguay in response to an unusual multiyear La Niña period. We characterized the hydrological drought using a set of indices based on daily, monthly and annual streamflow and water levels of the main rivers of LPB considering centennial records. We found that the recent drought is unprecedented in the last 50 years in terms of severity and duration. This is dependent upon the variable, river and hydrological drought index used, given that in some cases the recent drought showed unprecedented severity in the last 110 years. We also evaluated future streamflow projections from a set of global hydrological models (GHM) from the ISIMIP2b experiment to quantify if hydrological drought conditions might increase in frequency or intensity over the 21st Century. Even considering the projected precipitation increases over LPB, it is likely to face hydrological drought conditions particularly after the 2050s, with severity depending on the selected GHM and scenario. This will be more likely for the Paraná and Paraguay rivers, a result that calls for the design of improved waterway management, considering that the rivers are a key route for exports of grains and oils from Argentina and Paraguay.