Hydrological regime shifts driven by climate and anthropogenic interference in the Upper Paraná River Basin, Brazil

Abstract

Climate change coupled with land-use dynamics drives hydrological alterations, posing risks to water quality and sustainable water resource management. Understanding hydrological responses is key to analyzing the interplay between hydrometeorological processes, yet capturing spatiotemporal variability within basins remains challenging without an integrated assessment addressing interconnected dynamics and change points from climatic and human influences. This study developed a framework combining hydrology model, mutation test, and hydrological sensitivity analysis to evaluate this interplay in Upper Paraná River Basin, Brazil, from 1980 to 2020. The results indicated a general downward trend in the monthly average annual runoff and precipitation in the last decade. The hydrological mutation analysis identified obvious shifts in around 1999 and 2008. The results show a significant temporal shift in the drivers of runoff. Climate change dominated between 1980 and 1998, explaining approximately two-thirds of the total variation. The impact of climate change decreased by 23 % between 1999 and 2007 due to increased human activities such as reservoir construction and land-use change. From 2008 to 2020, continued precipitation reductions and anthropogenic interference led to a more complex hydrological response. Implementing targeted measures, such as regulating reservoir operations and optimizing irrigation system, offers viable pathways for ensuring the sustainable management and utilization of water resources.