ABSTRACT Understanding the synergistic impacts of climate change and human activities on runoff and sediment dynamics is crucial for sustainable watershed management in the Yellow River Basin. This study examined hydrological variations in the Helong section of the Chinese Loess Plateau from 1980 to 2020. The Mann–Kendall and Pettitt tests were used to detect trends and abrupt changes in precipitation, runoff, and sediment load, while the double mass curve method quantified the relative contributions of climate change and human activities. Pearson correlation analysis was applied to explore the relationships between land‐use change and water–sediment variations. Results show that mean annual precipitation (317.5 mm) exhibited a slight increasing trend, whereas runoff and sediment load averaged 2.99 billion m 3 and 279 million tons, respectively, both displaying significant decreasing trends. Abrupt changes occurred in runoff in 1998 and 2004 and in sediment load in 1998 and 2002. Land‐use patterns shifted markedly, characterised by decreasing cultivated land and increasing forestland and grassland. Attribution analysis indicates that human activities dominated runoff reduction, contributing 84.7% during 1999–2004 and 128.2% during 2005–2020, while contributing 71.8% and 113.4% to sediment reduction during 1999–2002 and 2003–2020, respectively. In contrast, climate change played a relatively minor role and partially offset the reduction in later years. These findings reveal that large‐scale ecological restoration has fundamentally altered the precipitation–runoff–sediment relationship, shifting the basin from a climate‐driven to a human‐regulated hydrological regime.
Zhi et al. (Fri,) studied this question.