Evident response of future hydropower generation to climate change

•Climate change impact on hydropower output was assessed in Pearl River basin.•Lower sustainability of hydropower is expected in future dry years.•No obvious change in hydropower output is found for future normal years.•Future wet years do not necessarily accompany increased hydropower output.•Increased reservoir inflow do not always lead to higher water use efficiency. Climate change has emerged as a key issue for hydropower management and development in future. This study systematically evaluates the impact of climate change on reservoir inflow, hydropower output, sustainability, and efficiency under the representative concentration pathway (RCP) scenarios (RCP2.6, 4.5 and 8.5) by taking the Pearl River basin in China as the case. The variable infiltration capacity model is coupled with global climate models to project future hydropower changes. It is shown that future reservoir inflow and hydropower output significantly differ from the historical ones. Dry years in future are projected to become drier leading to decrease in hydropower output that in turn reduces hydropower reliability and resiliency and increases the vulnerability. Wet years would get wetter, but the hydropower output does not necessarily increase possibly due to more surplus water released from reservoirs during flood seasons. For normal years, neither of reservoir inflow and hydropower output displays obvious changes. Moreover, water use efficiency of the West River in wet years and that of the North River in wet, normal and dry years would be lower in future, while the East River during non-flood seasons in dry years is expected to have higher water use efficiency. Our study can potentially provide an insight into the response of hydropower to climate change and help policy-makers and stakeholders manage future hydropower generation.