我国水资源总量2·8×1012m3,人均水资源量仅为世界平均水平的1/4和1/2,而且地区分布很不平衡,长江流域以北地区,耕地占全国耕地的65%,而水资源仅占全国水资源总量的19%。我国正常年份缺水量近400×108m3,其中农业缺水约300×108m3。农业是我国的用水大户,其用水量约占全国用水 The total amount of water resources in our country is 2.8 × 1012m3. The per capita water resources amount to only 1/4 and 1/2 of the world average. Moreover, the regional distribution is not balanced. In the area to the north of the Yangtze River valley, the arable land accounts for 65% of the national cultivated land, The water resources account for only 19% of the total water resources in the country. The water shortage in normal years in China is nearly 400 × 108m3, of which agricultural water shortage is about 300 × 108m3. Agriculture is China’s major water users, its water consumption accounts for the national water use