通过长江上游宜昌水文站、金沙江屏山水文站和嘉陵 江北碚水文站20世纪50年代以来径流量和输沙量的变化分析，表明宜昌站多年水沙关系未见有明显的变化，属正常波动，20世纪80年代以来，长江上游 要支流嘉陵江和金沙江的水沙关系发生了不同的变化，嘉陵江的江汉泥沙明显减少的趋势，金沙江呈略有增加的趋势，嘉陵江、金沙江两流域的侵蚀、产沙、输沙环境条件差异较大，人类活动的方式、程度，植被破坏与恢复，水土流失治理，水利工程抖沙和工程增沙等的明显差异，是20世纪80年代以业，嘉陵江和金沙江水沙变化不同的主要原因。

The observation data show that the sediment yield of Jialing River has decreased since 1980s, while the sediment yield of Jinsha River has increased. The cause of this change is analyzed. It is shown that the influence of engineering works on increment of river sediment of Jinsha River basin is much greater that in Jialing River basin due to the fact that the Jinsha River basin is characterized by deeply dissected plateau-gorge landform and the Jailing River basin by gently dissected hill landform. Current decline of sediment yield in the Jialing River is caused by the positive influences of human activities on reduction of sediment, such as revegetation, soil conservation and water conservation works. The increase of sedition, engineering works and channeling works.