This paper analyzes the long term (1965～1998) data of the monthly temperature and precipitation observed by 26 meteorological stations upstream from Lanzhou Hydrological Station in the Yellow River watershed and the monthly data of streamflow of the Yellow River, measured by 5 hydrological stations, so as to examine the streamflow regime and its change in the upper reaches of the Yellow River in recent 40 years. The results show that the climatic warming occurs universally in the upper reaches of the Yellow River, especially in winter, which has resulted in the temperature increase and shrinkage of frozen earth, sharp increase of evaporation, and the change of streamflow in the watershed; the precipitation in the watershed has been obviously reduced. The natural inflow from the upper reaches of the Yellow River is significantly reduced, especially since 1990. Viewing from the seasonal change of streamflow in the watershed, the streamflow is obviously increased in spring (from April to June) because of the increase of precipitation and the snowmelt runoff in this season; the streamflow is reduced in autumn and winter due to the decrease of precipitation in these seasons. It is considered that the streamflow change of the Yellow River is mainly affected by human activities, such as the streamflow regulation by reservoirs.
Arid Land Geography