MUDANÇAS CLIMÁTICAS E FATORES INFLUENTES NA OCORRÊNCIA DE CHEIAS EM GRANDES RIOS DA AMÉRICA DO SUL

Código

XXV-SBRH0212

Autores

João Paulo Lyra Fialho Brêda, Rodrigo Cauduro Dias de Paiva, VINÍCIUS ALENCAR SIQUEIRA, Walter Collischonn

Tema

STE04 - Cheias no Brasil: geração, previsão e impactos

Resumo

The projected increase in extreme precipitation has been associated with greater floods; however, most recent studies have argued that the reduced soil moisture could be causing the opposite effect. We aim to understand how the hydrometeorological variables affect flood discharge and what the projections are for South America. We used climate data from Eta simulations nested in 4 global climate models (BESM, CanESM2, HadGEM2-ES, MIROC5) as input for the MGB-SA hydrological model. Then we were able to project the climate impacts on extreme precipitation, antecedent soil moisture, and flood discharge for large rivers (> 1,000 km²) and understand how these variables are related. Our results showed a strong sign that antecedent soil moisture is expected to be reduced in most of the continent except in Southeastern South America (SESA). On the other hand, there are mixed signs for rarer precipitation but a clear spatial pattern for 2-year precipitations (RP2), which is expected to increase on the SESA and west Amazon and decrease on Central South America (CSA). For basins larger than 100,000 km², results indicate a negative change sign, especially for 2-year precipitations, meaning that rainfall events that generate ordinary floods in large South American rivers are expected to decrease in the XXI century due to climate change. In addition, while only 50% of the South American basins are expected to present reduced 2-year precipitations, nearly 70% of the rivers present a negative sign for 2-year floods, which can be attributed to the reduced antecedent soil moisture.