These results indicate that the precipitation distributions are uneven in every section of the YRB due to varying geographic location, topography and physiognomy characteristics; thus, the degrees of precipitation response in every section of the region are different. The regional precipitation has decreased in the middle and lower sections, in which the annual precipitations in the 2000s have decreased by 60 mm and 44 mm, respectively, compared with annual precipitations from the 1960s (Figure 5). The decadal mean precipitations of different sections and the corresponding coefficients of variation (Cv) are calculated in Table 2. The precipitation variation in the upper regions of the basin is considerably smaller than in other regions. The average precipitations in the Lanzhou and Toudaoguai sections decreased by 5 mm and 2 mm, respectively, in the 2000s compared to observations in the 1960s. The value of Cv in the Lanzhou section is relatively small, and the variation is not significant. However, Cv variations in different decades are significant in the Lijin section. The middle and lower sections of the YRB are close to sea level; therefore, they are influenced by monsoons. Monsoon precipitation is sensitive to meteorological variables (e.g., air temperature, wind speed, and net radiation) and significantly impacts some of the stations in this region. A relatively small monsoon effect was observed in the upstream Tibetan Plateau area (average elevation is above 4,200 m), as the precipitation measurements at most of the stations displayed insignificant trends (Liu & Cui 2011).