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利用1956~2004年长江源区水文和气象台站观测的流量、气温、降水资料,用气候诊断方法分析了该地区径流量的季节和年代际变化特征以及突变特点。结果表明:近50 a来长江源区月平均最大、最小和雨季、年及年较差流量均呈减小的趋势,月平均最小和最大流量分别出现在2月和7~8月,20世纪60和80年代的单峰峰值出现在7月,1970年代、1990年代的单峰峰值出现在8月,近14 a直门达水文站年径流共减少了96×108m3。雨季平均流量的距平基本经历了一个“正-负-正-负”的历史变化过程,雨季和过渡季节降水量、季节积雪融水量和高山冰雪融水量所形成的总流量呈下降趋势。枯季和雨季平均流量均经历了3次明显的转折,并具有10~12 a、6~8 a和3 a的共同变化周期。
Based on the observed flow, temperature and precipitation data from the hydrological and meteorological stations in the source region of the Yangtze River from 1956 to 2004, the seasonal and interdecadal variation characteristics and the abrupt change characteristics of runoff in this area were analyzed by means of climate diagnosis. The results show that in the past 50 years, the monthly average of the Yangtze River source area is the largest, the smallest and the rainy season, year and year are decreasing trend, the monthly average minimum and maximum flow occurred in February and July to August, 20th century The unimodal peaks appeared in July in the 60s and 80s, the unimodal peaks appeared in August in the 1970s and 1990s, and the annual runoff in the Zhuminda hydrological station decreased by 96 × 108m3 in the past 14 years. The anomalous average flow in the rainy season experienced a historical process of “positive - negative - positive - negative”. The total flow of precipitation in the rainy season and transitional season, seasonal snowmelt melt amount and alpine ice snow melt amount decreased trend. The average flow in dry season and rainy season all experienced three obvious transitions and had the same change cycle of 10 ~ 12 a, 6 ~ 8 a and 3 a.