关键词: 径流, 年内分配, 长江上游, 变化趋势

Abstract: In this paper，indexes of concentration，concentration period，unevenness and variation have been defined and calculated according to gauge records of runoff at the main station in the upper streams of the Yangtze River Basin． The main stations include the Pingshan Station on the Jinsha River，the Gaochang Station on the Minjiang River，the Beibei Station on the Jialing River，the Cuntan Station on the upper Yangtze River and the Wulong Station on the Wujiang River． And then the changes of annual runoff distribution in the upper streams of the Yangtze River Basin have been discussed． The results show that the unevenness of Beibei Station is greater than the other stations; the concentration unevenness of Beibei Station is the greatest and Wulong Station is the smallest． The concentration period of Wulong Station is in late June and in the other station is in July or August． The relative variation rate of Beibei Station is the greatest and Pinshan Station is the smallest． The inter-annual changes of annual runoff distribution were further analysed by the Kendall＇s rank correlation method． The results show that the unevenness，concentration and relative variation rate decreased obviously． The conclusions are meaningful for water resources management in the upper streams of the Yangtze River Basin．

Key words: runoff, annual runoff distribution, the upper streams of Yangtze River Basin, changing trends