On the Observations and Environmental Modeling in Xingó Hydropower Plant – São Francisco Basin, Brazil: Present and Future Hydroclimatic Features

Abstract

The São Francisco river basin plays a critical role in the hydroelectrical operational planning of Brazil. Understanding the hydroclimatic dynamic regime and, consequently, related climate changes is essential for decision-makers of the hydroelectrical sector. In this context, this work takes the Xingó hydropower plant and its drainage area as a reference for climatic and hydrological analyzes. Observed rainfall in the drainage basin and streamflow measurements in the power plant between 1975 and 2016 are used to assess the climatology of the region and to identify trends in the time series. In addition, a methodological framework based on numerical modeling of the hydroclimatic variables is employed to examine the representation of the present climate (1961 to 1990) and to investigate the future projections (2011 to 2100). The SMAP rainfall-runoff model and the Eta regional climate model nested within two global models are adopted in this investigation under the RCP4.5 and RCP8.5 IPCC scenarios. In Xingó, the average annual precipitation is about 978 mm and the average annual streamflow is 2,534 m³.s− 1. This region is marked by the monsoon cycle, with a clear rainy (October to March) and dry (April to September) period. There is no trend regarding precipitation, while the streamflow time series show a statistically significant decreasing trend in the present climate. Climate projections point to reduction in rainfall and streamflow during the 21st century. The results showed in this work revealed to be crucial to better understand the energy security for Xingó in the present and future climates.