我国是一个水资源短缺的国家，人 均水资源量仅为世界平均水平的四分之一，而且水资源的时空分布不均，南方水多，北方水少；丰水年水多，枯水年水少；夏秋降雨多，冬春降雨少。北方广大地区的生活、生产和生态用水，越来越短缺，已经成为制约我国国民经济、社会发展和生态环境 China is a country with a shortage of water resources. The per capita water resources amount to only one quarter of the world average. Moreover, the temporal and spatial distribution of water resources is uneven, with more water in the south and less water in the north. Less water; summer and more rainfall, winter and spring less rainfall. The living, production and ecological water use in the vast northern areas have become increasingly scarce and have become a major constraint to our national economy, social development and ecological environment