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长江水患严重,水土流失是致命因素。资料显示,由于长江中上游植被破坏日趋严重,泥沙俱下,洞庭湖蓄水能力锐减,湖面面积已由50年代初的4300多平方公里缩小到2600多平方公里,调汛能力从293亿m~3衰减到174亿m~3,平均每年进入洞庭湖的泥沙为1.29亿m~3。中国水土流失的面积目前已经达到367万km~2,占国土面积的38.2%,每年流失土壤达50亿t。水土流失恶化的趋势表现为,全国平均每年新增水土流失面积1万km~2;新增
Severe flooding in the Yangtze River is a fatal factor in water and soil loss. The data show that due to the increasingly serious damage to the vegetation in the middle and upper reaches of the Yangtze River, the sediment capacity of Dongting Lake has dropped drastically. The area of the lake has been reduced from more than 4,300 square kilometers in the early 1950s to more than 2,600 square kilometers. The flood control capacity has increased from 29.3 billion m 3 Declining to 17.4 billion m 3, and the average annual sediment entering Dongting Lake is 129 million m 3. The area of soil and water loss in China has now reached 3.67 million km2, accounting for 38.2% of the total land area and soil loss of 5 billion tons per year. The trend of deterioration of soil and water loss is as follows: the annual average area of soil and water loss in the country is 10,000 km 2;