JRC Technical Report-Extreme and long-term drought in the La Plata Basin: event evolution and impact assessment until September 2022

GUSTAVO NAUMANN; GUILLERMO PODESTÁ; J. MARENGO; ARIAS MUÑOZ; BARBOSA P.; CAMMALLERI C.; CUARTAS A. ; MARÍA DE ESTRADA; DE FELICE M.; DE JAGER A.; ESCOBAR C.; FIROVANTI G.; GIORDANO L.; HARST ESSENFELDER A.; HIDALGO C.; LEAL DE MORAES O.; MAETENS W.; MAGNI D.; MASANTE D.; MAZZESCHI D.; OSMAN M.; ROSSI L.; SELUCHI M; SKANSI M.; SPENNEMANN P.; SPINONI J.; TORETI A.; VERA C.

2022-06-01/2022-09-30

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Atmosfera

Atmosfera-Meteorologia

The current drought conditions across the Parana-La Plata Basin (LPB) in Brazil-Argentina have been theworst since 1944. While this area is characterized by a rainy season with a peak from October to April, thehydrological year 2020-2021 was very deficient in rainfall, and the situation extended into the 2021-2022hydrological year. Below-normal rainfall was dominant in south-eastern Brazil, northern Argentina, Paraguay,and Uruguay, suggesting a late onset and weaker South American Monsoon and the continuation of drierconditions since 2021. In fact, in 2021 Brazilian south and south-east regions faced their worst droughts innine decades, raising the spectre of possible power rationing given the grid dependence on hydroelectricplants. The Paraná-La Plata Basin drought induced damages to agriculture and reduced crop production,including soybeans and maize, with effects on global crop markets. The drought situation continued in 2022in the Pantanal region. Dry meteorological conditions are still present in the region at the end of September 2022 with belowaverage precipitation anomalies. Soil moisture anomaly and vegetation conditions are worst in the lower part of the La Plata Basin. Conversely, the upper and central parts of the basin show partial and temporaryrecovery.Seasonal modelling systems consistently forecast negative precipitation anomalies over the LPB as aresponse to the negative sea surface temperatures (SST) anomalies in the tropical Pacific associated with La Niña condition. There are high chances that La Niña conditions will prevail for the third spring and summer in a row (last time was during 1998-2001). Similarly, multi-annual to decadal modes of climate variability (i.e., AMO, PDO) have been in a phase that favours drought in the LPB in the period 2019/2020-present.