The Yellow River Basin (YRB) suffers from water shortage, and the contradiction between human and water is prominent. The upper reaches of the Yellow River (UYR) flow through the Qinghai-Tibet Plateau region, which is extremely sensitive to climate change and human activities. The annual runoff upstream of the Tangnaihe station accounts for around 1/3 of the total runoff in the YRB. Thus, the UYR is an important water conservation area of the YRB. It is of great significance to carry out hydrological simulation of the UYR and quantify the historical pattern and future tendency of runoff changes for guiding the efficient use of water resources and the high-quality development of the YRB. To this end, this paper collected the runoff observation data of the Tangnaihe station during 1956-2022. Based on the eWater Source platform, a combined model of IHACRES-CMD and GR4JSG was established considering both the rainfall-runoff and snow/ice-runoff patterns. The validation results showed that the combined model had good simulation accuracy and was suitable for the study of runoff changes in the UYR. Taking the meteorological conditions and land uses during different periods as the driving factors of the model, the multi-scenario calculation and analysis was carried out to reveal the contribution of different influencing factors to the runoff change. The results show that climate change was the main factor affecting runoff changes in the UYR in the past.
