The Spatial and Temporal Characteristics of Precipitation in The Inland Region of Qinghai Province

The inland region of Qinghai Province is located in the northwestern part of the province. The region is in arid and rainless environment, where the precipitation is spatial maldistribution. According to the third-level zoning of water resources in the inland region of northwest China, the inland region of Qinghai Province can be divided into three sub-regions: the western Qaidam Basin, the eastern Qaidam Basin and the Qinghai Lake water system region. The precipitation in these three sub-regions decreases from east to west. In this paper, linear fitting method, Mann-Kendall test method and Morlet wavelet analysis method were used to analyze the annual change of precipitation data from 1956 to 2013 in the inland region of Qinghai Province and three sub-regions, and the mutations and the periodic characteristics of the annual series were measured and analyzed. The results of linear fitting method indicate that the precipitation in the inland region of Qinghai Province is increasing during this period, with the strongest trend in the eastern Qaidam Basin and the weakest in the western Qaidam Basin. The results of the Mann-Kendall test method indicate that the precipitation in the inland region of Qinghai Province changed abruptly in 1984 and presented a marked upward trend after 1986. An abrupt change of precipitation of the western Qaidam Basin was identified in 1962, and as for eastern Qaidam Basin the abrupt change happened in 1984. A marked upward trend of precipitation of the western Qaidam Basin occurred during 1970-1995 and after 2007, as for eastern Qaidam Basin the trend happened after 1986. There were no abrupt change and significant upward trend in the Qinghai Lake water system region. The results of Morlet wavelet analysis method indicate that the precipitation in the inland region of Qinghai Province shows periodic "increasing-decreasing" oscillations, the first main cycle is 22 years, and the second and third cycles are 16 years and 8 years. For the western Qaidam Basin, the first main cycle is 32 years, the second cycle is 7 years. For the eastern Qaidam Basin, the first main cycle is 26 years, the second and third cycle is 15 years and 9 years. For the Qinghai Lake water system region, the first main cycle is 26 years.