PROPAGAÇÃO DE SECAS METEOROLÓGICAS PARA SECAS HIDROLÓGICAS NO SUL DO BRASIL

Código

END139

Autores

Vinícius Bogo Portal Chagas, ALENA GONZALEZ BEVACQUA, Pedro Luiz Borges Chaffe

Tema

2 - Previsão e monitoramento de estiagem/seca

Resumo

The effects of meteorological droughts propagate through the hydrological system, possibly producing hydrological droughts. This propagation determines the vulnerability of a region to droughts and it can be used as an early warning system. In Southern Brazil (SB), the propagation from meteorological to hydrological drought has been little explored. In this work, we verify how much time does it take for a meteorological drought to produce a hydrological drought in Southern Brazil. Additionally, we verify if this information can be used as a hydrological drought forecast. We evaluated the Standardized Precipitation Evapotranspiration Index (SPEI) and the Standardized Streamflow Index (SSI) of 112 basins in SB, from 1980 to 2013. The relationship between meteorological and hydrological drought was examined by cross-correlating the SPEI and SSI series. Results showed that the propagation time in SB ranged from one to five months. However, it is expected that, in most of the basins, a two-month meteorological drought leads to strong effects on the streamflow. In the southern part of SB (i.e., Rio Grande do Sul) the effects of meteorological droughts on the streamflow are more persistent and can be felt after a single month. High correlation values of the SPEI with the lagged SSI in the southern part of SB demonstrate that the SPEI series are a potential source for early warning of hydrological droughts. This knowledge indicates that standardized indices might be used as early warning systems for drought events help monitoring and mitigating those events.