Bias correction based runoff change attribution quantification for the typical water conservation catchment in the upper yellow river basin

Water is highly crucial to support social economic development and ecosystem improvement. The Yellow River has been nurturing China civilization and flourishing prosperity with Limit water resources. The hydrological regime in the water conservation areas of the Yellow River basin has been highly influenced by climate change and intensive Human activities. It is significant to quantify attribution of changes in runoff and water conservation for ecological protection and economic development. Taking the Datong River in the upper Yellow River basin as a case, this study proposed a bias correction based runoff change attribution quantification method, the impacts of environmental change on runoff were investigated based on analyzing characteristics of runoff evolution during 1961–2020. The results showed that (1) the measured annual runoff at Xiangtang station showed a significant decreasing trend from 1961 to 2020, with an abrupt change occurring in 1990. The recorded annual runoff in 1991—2020 decreased by 12.0% relative to baseline of 1961—1990, among which, runoff decreased by 27.7 mm in period from April to October and increased by 4.4 mm in other months. (2) The RCCC-WBM model performs well in monthly natural discharge simulation for the baseline period of 1961—1990 with Nash–Sutcliffe efficiency coefficient of 0.74 and relative error of 0.46%. (3) During the period of 1991—2020, climate change increased runoff by 22.3 mm, while Human activities decreased runoff by 45.5 mm. The operation of water diversion projects constructed in the Datong River is the dominate reason for the reduction in runoff at the Xiangtang hydrometric station. Enhancing ecological conservation and water retention capacity in the Datong River Basin is crucial to ensuring water security and ecological sustainability for regional economic development.