Trends, Abrupt Changes, and Periodicity of Streamflow in Qinghai Province, the Northeastern Tibetan Plateau, China

摘要

The Qinghai-Tibet Plateau is a more sensitive area of climate change and fragile zone of ecological environment. Qinghai Province is an important component of the Qinghai-Tibet Plateau, and the study of streamflow in the province is of great significance for understanding the situation of water resources. Based on hydrological data of hydrological stations in Qinghai, the spatiotemporal variations of streamflow from 1956 to 2013 were analyzed by Mann-Kendall analysis and Morlet wavelet analysis. The results indicated that the annual streamflow of the Yangtze River basin, Qaidam basin, Qinghai Lake basin, and Lantsang River basin showed significantly increasing trends during 1956-2013, while the Yellow River basin showed no significant trends or downward trends. Changes in precipitation, glacier melt, and snowmelt caused by climate warming might be a major driver of changes of streamflow in the source regions of the Yangtze River and Lantsang River basins. The trend variations of flow in the Yellow River basin may be affected by precipitation, evaporation caused by increased temperature, and anthropogenic impacts. The abrupt changes of streamflow at Tuotuohe, Delingha, and Nachitai stations were mainly in the early 2000s, while the abrupt changes of streamflow in Zhimenda station, stations in the Yellow River basin, Qinghai Lake basin, and Lantsang River basin appeared primarily in the early 1960s and the early 2000s. Most of the streamflow in Qinghai Province was abundant after about 2007, and the dominant periods with low frequency fluctuation (about 12 years) and inter-decadal (about 44 years) oscillations in Zhimenda and Tangnaihai stations and low frequency fluctuation (about five years) in other stations.