长江三峡区土壤侵蚀规律及泥沙来源分析

An Analysis of Soil Erosion Rules and Sediment producing Sources in the Region of Three-Gorge of the yangtze River

泥沙是水库建设的大敌,修建大坝首先要考虑土壤侵蚀和水库淤积问题。本文通过1981～1990年期间研究确定,三峡区的年侵蚀量为1.57亿t,年入库泥沙量为4000万t。随着植被的破坏和演替,侵蚀量由低到高。林地、灌丛、草地和农地的年侵蚀量,分别占三峡区总侵蚀量的6.19％,10.76％,23.05％和60％,入江泥沙量分别占入库泥沙总量的5.95％,12.42％,35.46％和46.16％。农地是主要产沙区。重力侵蚀推移质多,一旦入江,对三峡工程将构成严重威胁。移民上山进行农业生产,共将增加三峡区产沙量1000～1200万t,增加入江泥沙量500～600万t。对三峡区的侵蚀泥沙问题必须有一个切合实际的估价。

Sediments or silts are the main obstacle in building reservoirs. In constructing a dam, the problems of soil eroion and reservoir siltation should first be taken into account. Through 1985—1990 studies, this paper reports that an annual soil erosion is 157 million tons, and an annual incoming sediment into reservoir is 40 million tons in Three-gorge reservoir region of the Yangtze River. With the destruction of vegetation cover and succession, an amount of soil erosion becomes from lower to higher. An amount of soil erosion from forest land, shrub land, grassland and agricultural land accounts for 6.19%, 10.76%, 23.5% and 60% of total amount of soil erosion, while an amount of incoming sediment into reservoir consists of 5.95%, 12.42%, 35.46% and 46.16% respectively. Agricultural land is the major sediment producing area in the reservoir region. Gravitational erosion can produce more bed loads.Once they enter the reservoirs, they have formed a serious threatto the Three Gorge engineering structures. With the immagrates going up the mountain for agroproduction, the sediment production increase by 10～12 million tons in the reservoir region, and the incoming sediment into reservoir increases by 5～6 million tons. Therefore, it is necessary to have a practical evaluation of the problem of the eroded sediment in the reservoir regions.