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1 南水北调西线工程的必要性1.1 我国水土资源地区分布不均衡南方水多地少,北方地多水少,长江以南水资源量占全国的81%,耕地占全国的35.9%;长江以北水量占全国的19%,而耕地却占全国的64.1%。黄河为我国第二大河,但其水量仅占全国河川径流量的2%,位于七大江河的第四位。黄河上中游的兰州至三门峡河段(涉及甘、宁、蒙、陕、晋五省区),人均水量为320m~3,是全国人均水量的1/8;亩均水量110m~3,为全国
1 Necessity of Western Route of South-North Water Diversion Project 1.1 Unbalanced distribution of water and soil resources in China The southern China is less water-rich with less water in the north. The water resources to the south of the Yangtze River account for 81% of the national total and arable land accounts for 35.9% of the national total. The north of the Yangtze River Water accounts for 19% of the country, while arable land accounts for 64.1% of the country. The Yellow River is the second largest river in China, but its water volume accounts for only 2% of the country’s total river runoff. It ranks fourth in the seven major rivers. The Lanzhou-Sanmenxia reach of the upper and middle reaches of the Yellow River (covering 5 provinces and autonomous regions including Gansu, Ningxia, Mongolia, Shaanxi and Shanxi) has a per capita water volume of 320m-3, which is 1/8 of the national average per capita. The average water amount per mu is 110m3,