北京给水水源的历史变迁与终极选择

Historical Transformation and Ultimate Choice of Drinking Water Sources in Beijing City

古都北京因玉泉山泉而兴旺800多年,密云水库在玉泉山泉断流后则承担起北京主要地表水源地的角色。然而,还不到50年时间,密云水库便入不敷出,再加上北京人口的急剧膨胀,缺水已经成为阻碍北京经济可持续发展的一大瓶颈。正因如此,南水北调在经历了近50年争议后不得不开工建设,并于1年前通水入京。南水北调固然可以解决北京燃眉之急的近渴,但能否一劳永逸地满足远渴,其争议并未消停。除工程经营期限的可靠性和安全性外,南水北调全成本价格最为关键;50年经营期全成本价格≥10元/m^3(调水及处理成本)。这就为海水淡化项目上马提供了理由。实际上,海水淡化就是俗称的"唤雨",是一种模拟自然水循环的有效途径,对其利用不仅有着价格优势(综合成本≤5元/m^3),而且还不与自然抢水,对生态环境的影响最小。因此,北京持久性地解决长期缺水问题的出路应着眼于海水淡化,特别是"风力发电+海水淡化+盐业化工"这种三位一体的生态技术。

As an ancient capital, Beijing had ever been thrived for over 800 years by the Yuquan Spring. The Miyun reservoir has run behind its reenlistment after serving for less than 50 years as the main surface water source. Moreover, expanded population of Beijing makes its economic development hindered by water shortage which has actually ＇ kidnapped＇ Beijing. Under the circumstance, the huge project of South-to-North Water Diversion （SNWD） was initiated after evaluated and debated for almost half a century, and finally water from the Yangtze River has been coming into Beijing. Definitely, SNWD can meet the recently urgent need of water for Beijing. However, there are also more debates over its future safety of water supply. Besides the reliability and safety during potential operation, the total water transportation price is a crux for SNWD; the calculated water transportation and treatment price for a 50- year operational period is at ≥ 10 Yuan/m^3, which becomes a reason why projects of seawater desalination are strongly proposed now. In fact, desalination is an effective approach to simulate the natural water cycle, which is called ＇controlling rain＇ among the people. Desalination has a low water price （ ≤ 5 Yuan/m^3 ）, can avoid water fight with the nature and weakly affect ecological environment. Thus, desalination should be regarded as a future, reliable and sustainable water resource for Beijing, especially under the proposed trinity ecological pattern： wind energy ＋ desalination ＋ salt/minerals production.