Deciphering the influence of climate change and human activities on the drought propagation

Study region: The Yiluo River Basin (YLRB), China Study focus: Understanding the alterations in drought propagation under evolving environmental conditions is crucial for the efficient management of water resources. In this study, the 'simulation-observation' comparison method was employed to analyze the drought propagation in distinct periods: baseline, simulated, and disturbed periods. This facilitated the quantification of the impact of climate change and human activities on drought propagation characteristics, such as the response time of the Standardized Streamflow Index (SSI) to the Standardized Precipitation Index (SPI) and the propagation threshold. New hydrological insights for the region: The response times of the SSI to the SPI has been prolonged at monthly and seasonal scales due to climate change, while it has been reduced at the annual scale. The impact of human activities on the lengthening of response time is only evident at longer temporal scales. Human activities have contributed to higher thresholds for severe and extreme droughts on monthly and annual scales, increasing the probability of extreme droughts. Meanwhile, climate change has partially offset the negative impacts of human activities. However, at the seasonal scale, climate change is the main cause of the increasing propagation thresholds. The conclusions drawn from this research provide valuable insights for the development of policies aimed at managing drought in a changing environment