北京市虚拟水消费与贸易

北京市作为水资源极度紧缺的城市,亟需提高水资源的利用效率。本文基于多尺度投入产出分析模型,对2012年北京市虚拟水消费及贸易情况进行了核算与分析,并与2007年的结果进行了比较。计算结果表明：2012年北京市消费引发的虚拟水用量高达139.5亿m³,是基于生产的直接实体用水量（35.9亿m³）的3.89倍;对比2007年,虚拟水消费增长（23.7%）远比直接用水增长（11.8%）快。北京市使用的全部水资源中仅有5%由北京本地供应,有超过3/5从国内其他省市调入,约35%从世界其他国家进口。与此相对应,这些水资源有1/5被北京本地消费使用,约3/4被调出到国内其他省市,6%被出口至其他国家。与2007年相比,2012年北京市国内虚拟水贸易由净调入转为净调出,净调出量为2007年净调入量的1.1倍;而国际虚拟水贸易由净出口转为净进口,净进口量为2007年净出口量的837.2倍。北京市2012年净输入虚拟水资源103.6亿m³（全部来源于国际贸易）,有效地避免了对本地水资源的过度开采。与此同时,北京市通过转口贸易的形式将大量进口的虚拟水调出到了中国其他省市,为缓解国内水资源紧张局面作出了贡献。未来北京市应当在考虑能源矿产供应安全及消化国内过剩产能的前提下有策略性地增加矿产、能源、建筑和交通运输设备等部门部分产品的进口,以达到节约我国水资源及全球范围内水资源高效利用的目的。

Virtual water consumption and trade of Beijing

As a city suffering from serious water resources shortage, Beijing is in urgent need to improve water use efficiency. Based on the method of multi-scale input-output analysis, this work calculates and analyzes the virtual water consumption and trade of Beijing in 2012, and compares the results to that of 2007. The results indicate that the consumption-based water resources use of Beijing were estimated up to 13.95 billion m³ in 2012, which were 3.89 times larger than the production-based direct water resources use (3.59 billion m³). Compared with 2007, the virtual water consumption (23.7%) grew faster than direct water use (11.8%). For all water resources related to Beijing, only 5% was from local water withdrawal, while more than 3/5 was domestically imported from other Chinese regions and about 35% was imported from foreign countries. Meanwhile, about 1/5 of these water resources was consumed to meet Beijing's local final demand, approximately 3/4 was exported to other domestic regions, and 6% was exported to other countries. Beijing changed from a net domestic virtual water importer in 2007 into a net exporter in 2012, and the net domestically exported virtual water in 2012 was 1.1 times larger than the net import in 2007. On the other hand, Beijing changed from a net international virtual water exporter in 2007 into a net importer in 2012, and the net international virtual water import (19.60 billion m³) was 837.2 times larger than the net export (0.02 billion m³) in 2007. Beijing net imported 10.36 billion m³ virtual water in 2012 (all from international trade), which has successfully avoided the over-withdrawal of local water resources. At the same time, Beijing re-exported plenty of internationally imported virtual water to other Chinese regions, which has contributed a lot to alleviate domestic water shortage pressure. In order to reduce domestic water resources use and improve water use efficiency worldwide, Beijing is suggested to strategically increase the international import of mineral, energy, construction and transportation equipment products under the consideration of energy and mineral resource supply security, and to absorb domestic excess capacity in the future.