Streamflow and sediment change of major rivers in the Eastern Tibetan Plateau from 1960 to 2020

Being recognized as the "Asian Water Tower", the Tibetan Plateau (TP) plays a pivotal role in regulating downstream water resources. However, significant alterations in runoff and sediment transport have been witnessed within its headwaters region, primarily due to the combined impacts of climate change and human activities. This study focuses on five major river basins in the Eastern TP, including the Yellow River, Yangtze River, Lancang River, Nujiang River, and Yarlung Zangbo River. A comprehensive analysis of the annual and seasonal variations in streamflow and sediment data from 1960 to 2020 (recent 6 decades) was conducted, utilizing extensive hydrological station measurements and various statistical methods, including the Pettitt change-point test and linear regression algorithm. Key conclusions include: ① Over the past six decades, the annual runoff in the Yangtze River and Nujiang River basins exhibited a significant upward trend, while changes in other basins remained less pronounced, with considerable spatial variability in runoff alterations. A majority of stations experienced an abrupt shift in annual runoff around 2006, followed by a sustained increase in the subsequent decade. As for the annual sediment transport, the Yangtze River basin showed an insignificant increase, while the Yellow River, Lancang River, and Yarlung Zangbo River basins all exhibited insignificant decreases. The variation trends was overall consistent with annual runoff, but with greater uncertainty. ② In terms of seasonality in the past six decades, the winter and spring runoff in upstream stations displayed a consistent rising trend across all basins, while the variation in summer and autumn runoff mirrored that of annual runoff, and the summer runoff demonstrated a spatial pattern, characterized by a distinct "northward increase, southward decrease" trend. ③ The development of water resources in the Lancang River basin has disrupted the natural runoff patterns downstream, notably manifesting as a sudden shift in the annual distribution of runoff, with reduction in seasonal variation. These findings enhance our understanding of streamflow and sediment changes in the Tibetan Plateau, offering valuable insights for predicting runoff trends and informing water resource management decisions.