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长江自江源至宜昌为上游,长江上游段干流全长4511公里,流域面积100.5万平方公里,自西向东跨我国大陆一、二级阶地及其过渡带:一级为青藏高原腹地及其东部:二级包括云贵高原一部分及四川盆地、地势自西北向东南倾斜。流域内气候分属青藏高寒区和中亚热带季风区,西部寒冷、干燥、少雨,中部和东部温暖、湿润、多雨,年平均气温2°～20℃,多年平均降雨量约240～2500毫米。一、水土流失现状除在人烟稀少的青藏高原及高寒山地以冰川、冻融侵蚀为主外,长江上游水土流失的形式,一般均以水蚀为主,并因地质条件不同.局部地区还存在滑坡,泥石流等重力侵蚀及混合侵蚀类型。水蚀区的侵蚀强度以人类不合理的土地经营规模而有所消长。
The Yangtze River flows from Yichang to the upper reaches of the Yangtze River. The upper reaches of the Yangtze River have a total length of 4,511 kilometers and a catchment area of 1,500,000 square kilometers. From the west to the east, they cross the first and second order terraces of China’s mainland and their transitional zones: the first is the hinterland of the Qinghai- : Level 2 includes a part of the Yunnan-Guizhou Plateau and the Sichuan Basin, and the terrain slopes from northwest to southeast. The climate in the basin belongs to the Qinghai-Tibet alpine region and the subtropical monsoon region. The western part of the basin is cold, dry and drizzle. The central part and the eastern part of the basin are warm, humid and rainy. The annual average temperature is 2 ° -20 ℃ and the annual average rainfall is about 240-2500 mm. I. Current Status of Soil and Water Loss Apart from sparsely populated glaciers and freezing-thawing erosion in the sparsely populated Qinghai-Tibet Plateau and alpine mountains, the pattern of soil erosion in the upper reaches of the Yangtze River is generally dominated by water erosion and due to different geological conditions. Landslides, Debris flow and other types of gravity erosion and mixed erosion. The erosion intensity of water eroded areas has declined with the unreasonable scale of land management by human beings.