北京属温带大陆性季风气候，多年平均降水量为595mm，水资源极为短缺，全市人均年占有水量450m3，是全国人均占有水量的六分之一，居全国三十个省、市、自治区的倒数第四位，在世界上120多个大城市中居百位之后。北京的水一部份来自外省、区，如永定河是内蒙、山西、河北等地由 Beijing is a temperate continental monsoon climate with an average annual rainfall of 595mm and an extremely short supply of water resources. The city’s per capita annual water consumption is 450m3, which is one sixth of the national average and occupies one-sixth of the national average. It ranks among the top 30 provinces, municipalities and autonomous regions in the country Four, in the world after more than 120 big cities in a hundred. Part of Beijing’s water comes from other provinces and regions, such as Yongdinghe, Inner Mongolia, Shanxi and Hebei