Climatic Change in the Lake Qinghai Watershed in Recent 47 Years

The meteorological data from seven representative stations around the Lake Qinghai during 1959-2005 were used to investigate climate change of the Lake Qinghai watershed by means of Thiessen polygon method,the climatic tendencies were analyzed by Mann-Kendall test.The results are as follows: (1)In the recent 47 years,the decadal variation of precipitation is significant,there are ascending tendencies in the 1960s,1980s and 1990s,while precipitation in the 1970s shows downward trend,and there are ascending trend of long-term change in summer and annual precipitation respectively;(2) The ascending tendency of temperature is remarkable,and the average temperature during 1987-2000 increases 0.79 ℃ compared with that during 1961-1986;(3) The tendencies of annual and seasonal evaporation present positive trend;(4) The precipitation has a significant correlation with the lake-level and runoff of the Buha River and the Shaliu River.Based on nine years scale,the precipitation in autumn will increase in the coming 5 years,this may decrease the magnitude of the decline of the lake-level.