Socioeconomic drought propagation in a hydropower cascade system

Storage reservoir systems influence meteorological, hydrological, and socioeconomic droughts. However, teasing out the effects of reservoirs on drought propagation is challenging due to the integrated operation of hydropower systems. We examine how meteorological droughts propagate into hydrological and socioeconomic droughts within the Paraná River Basin (890,000 km2) in Brazil, using 25 years of daily data of 61 hydropower plants. We define socioeconomic drought using the ratio of hydropower generation to installed capacity, and use SPI and SSI for meteorological and hydrological droughts. Our results indicate that all drought types have become more frequent over the years. On average, meteorological droughts take nine months to propagate through the reservoir system and generate a socioeconomic drought. The slow propagation is contrasted by a faster recovery of socioeconomic droughts, which can be attributed to the operation of the entire system. These findings highlight the importance of considering reservoir cascades in predicting drought developments.