Analysis of Extreme Rainfall Indexes in Future Scenarios in the Ribeira de Iguape (SP) River Basin

Abstract

Extreme precipitation events are caused due to excess or lack of rain sufficient to cause flooding, prolonged dry spells and droughts that can affect the population's life. This work aims to study the precipitation behavior through climatic extremes indices (CDD, R10mm, Rx1day, Rx5day and R95p) in Alto Juquiá, Baixo Ribeira and Ribeira de Iguape sub-basins located in Ribeira de Iguape River Basin, in both current and future contexts. The Alto Juquiá sub-basin feeds the São Lourenço Water Production System, which supplies part of the municipalities of Greater São Paulo. The extreme index data observed and simulated by two regional climate models: Eta-HadGEM2-ES and Eta-MIROC5. Historical analysis of the observed data identified an increasing trend in the number of consecutive dry days (CDD) and extremely rainy years (R95p) in the three sub-basins. The projections of the two models and scenarios indicate for closer future (2006-2040) longer periods of drought (CDD) and a lower intensity of rain (R95p and Rx1day) until 2099. It is also possible to infer that the model HadGEM2-ES performed better, since the systematic errors were lower in the Alto Juquiá and Rio Ribeira de Iguape sub-basins.

Keywords
indexes precipitation extremes; projection; hydrographic basin Ribeira de Iguape River