北京市水足迹计算与分析

摘要

水足迹指的是在一定物质生活标准下,生产一定人群(个体、城市或国家)消费的产品和服务所需要的水资源数量.虚拟水是指生产产品和服务所需要的“虚拟”水资源,不是真正意义的水,而是以“虚拟”的形式包含在产品中的看不见的水.水足迹不仅仅包括对实体水的消费,更重要的是包含了虚拟水消费的部分.分析区域内的水足迹量及其构成,能够从消费的角度展现对水资源的占有情况,展现出通过产业链及产品贸易而产生的该区域对其他区域的水资源占有情况或其他区域对本区域的水资源占有情况.本研究采用基于投入产出表的水足迹计算方法,估算了北京市2002年的水足迹状况,分析了水足迹构成.结果表明:北京市2002年水足迹为86.26亿m3,其中70%用于居民消费,30%用于政府消费;总的人均水足迹为606.21 m3,城镇居民人均水足迹为537.69 m3,农村居民人均水足迹为197.12 m3; 2002年总水足迹中,实体水消费占8%,虚拟水消费占92%,虚拟水净流入量为14 98亿m3,占总水足迹的17.4%.结果证明,在消费结构中,虚拟水占主要部分,实体水比例很低；受产业链和工艺的影响,不同消费品(服务)的虚拟水含量并不相同.虚拟水流入能够降低对本区域水资源的占有,并没有从根本上减少水资源的消耗,只是将压力转移到了其他区域.研究结果可为节约用水模式和北京市水资源管理提供决策参考.%Individual or community water footprint (WF) is defined as the total volume of water used to produce goods and services consumed by the individual or community. Virtual water content of a product (a commodity, good or service) is the volume of water used to produce the product. It is the sum of water used in the various stages of the production chain. Total water footprint (TWF) includes real water consumption, and more importantly virtual water consumption. By analyzing the volume and structure of WF, the consumption of water resources in any given region in terms of finished products can be determined. This paper calculated TWF of Beijing City for 2002 based on water input-output table. It also analyzed TWF composition in the city. The analysis showed that Beijing's TWF in 2002 was 8.626 billion m3. About 70% of TWF was used in resident consumption and 30% in government consumption. The per capita average WF of Beijing was 606.208 m3, that of urban residents was 537.690 m3 and the per capita average WF of rural residents was 197.123 m3. Real water consumption accounted for 8% of TWF, whereas virtual water consumption accounted for 92% of TWF. Virtual water net inflow was 1.498 billion m3, which accounted for 17.4% of TWF. The results illustrated that virtual water accounts for the bulk in the water consumption structure. Percent of entity water of Beijing was very small. Because of differences in production chains and trades, the content of virtual water in commodities and services varied significantly. Virtual water import reduced possessed water resources in Beijing. However, the volume of water consumption did not reduce the pressure on water resources, which just was transferred to the surrounding regions. This paper provided valuable modes of water-saving and waterrecourses management in Beijing.