目前,全世界正面临一场严重的、普遍的水危机。地球上水源的总量约为13.5亿立方公里,其中海水占了96.5％,陆地水只有3.5％,而且大部分是冰川、雪山、深层地下水和土壤水,人类尚无法利用。目前人类可以利用的淡水仅限于江河湖泊和浅层地下水,而这部分水仅占淡水总量的0.35％。造成世界性水危机的主要原因是由于全球降水时空分布不均匀,全球总降水量的78％落入海洋,只有22％落在陆地上。世界上现有的水量和1000年前基 At present, the world is facing a serious and widespread water crisis. The total amount of water on Earth is about 1.35 billion cubic kilometers, of which 96.5% of sea water, land water is only 3.5%, and most of them are glaciers, snow-capped mountains, deep groundwater and soil water, humans still can not use. Currently, freshwater available to humans is limited to rivers, lakes and shallow groundwater, which accounts for only 0.35% of total freshwater. The main reason for the worldwide water crisis is that due to the uneven temporal-spatial distribution of global precipitation, 78% of the global total rainfall falls into the ocean and only 22% falls on land. The world’s existing water base and 1000 years ago