CONICET | Buscador de Institutos y Recursos Humanos

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. The hydrological drought caused complications for commercial navigation, interruptions in the water supply for urban centers, affectation of fishing activities, and impact on coastal environments and biodiversity, among others. 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 (e.g. Paraná, Paraguay, Uruguay rivers and some of its tributaries) considering centennial records. Using the threshold level method and the standardized streamflow index, we identified that the recent hydrological drought in the La Plata Basin, particularly considering the streamflow of the Paraná River, 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. Historical and future streamflow simulations were obtained from the Inter-Sectoral Impact Model Intercomparison Project version 2b (ISIMIP2b) hydrological models, which comprises 10 GHM forced by four general circulation models (GCM) for the period 1950-2099. Two representative concentration pathways were selected (RCP2.6 and RCP6.0) to evaluate future changes in streamflow over LPB. Even considering the projected precipitation increases over Southeastern-South America, it is likely to face hydrological drought conditions over LPB particularly after the 2050s, with frequency and severity depending on the selected GCM/GHM and scenario. This will be more likely for the Paraná and Paraguay rivers, a result that calls for the design of an improved waterway management, considering that the rivers are a key route for exports of grains and oils from Argentina and Paraguay.

enviar mensaje