投入产出法在虚拟水消费与贸易研究中的新应用

虚拟水是缓解水资源危机的一种途径。投入产出法是研究虚拟水的主要方法之一，可分为单区域投入产出模型（SRIO）和多区域投入产出模型（MRIO）。鉴于SRIO 和MRIO单独应用时存在一定局限性，论文提出同时运用单区域投入产出表和多区域投入产出表研究虚拟水，即：利用SRIO 计算完全用水系数，并直接利用单区域投入产出表区分本地水足迹与外来水足迹，再根据多区域投入产出表分析区域间的虚拟水贸易。广东省的案例研究显示：①2007 年广东省水足迹为333.9×10⁸ m³，其中本地水足迹223.6×10⁸ m³，外来水足迹110.3×10⁸ m³；②广东省同年虚拟水输出量445.4×10⁸ m³，输入量454.1×10⁸ m³，其虚拟水的外部来源主要是湖南、广西和浙江。结果表明以上方法可全面计算完全用水系数，有效区分本地水足迹与外来水足迹，揭示区域间的虚拟水贸易关系，为水资源管理决策提供方法支持。

New Application of the Input-output Framework in the Study of Virtual Water Consumption and Trade

Global water crisis is looming. Virtual water, the amount of water necessary to produce a good or a service, provides key new information for policy makers, because virtual water trade can compensate for water shortages through the geographical shift of good production and the sectoral shift of water consumption. Thus virtual water serves as an alternative way of solving water resources crisis. The input-output framework is one of the main methods of studying virtual water, which can be classified into Single Regional Input-Output model (SRIO) and Multi-Regional Input-Output model (MRIO). However, there are some limitations when applying SRIO or MRIO alone, i.e., SRIO cannot distinguish local water footprint from external water footprint, thus providing very little information for inter-regional virtual water trade, while it is difficult to obtain accurate dataset for MRIO, leading to underestimation. To overcome the shortcomings of these two models, this paper aims at proposing a new method, which can separate local water footprint from external water footprint directly based on single regional input-output data that is much easier to obtain than multi-regional input-output data. In the proposed method, SRIO is adopted to calculate the total water consumption coefficient as the estimated coefficient is much accurate, and then local and external water footprint is separated directly by using single regional input-output dataset, and finally virtual water flow among different regions can be analyzed through inter-regional input-output data. The application of the proposed method to Guangdong Province showed that: 1) the total water footprint of Guangdong Province in 2007 was 333.9×10⁸ m³, with local water footprint of 223.6×10⁸ m³ and external water footprint of 110.3×10⁸ m³, respectively; and 2) in 2007, the virtual water flowing out of Guangdong Province was 445.4×10⁸ m³, and the flowing in was 454.1×10⁸ m³ which mainly came from Hunan, Guangxi and Zhejiang provinces. The results indicate that the proposed method is effective in obtaining a complete total water consumption coefficient thus can obtain accurate estimation, and is easy to distinguish local water footprint from external water footprint and specify the water flow between regions. Virtual water and water footprint can be quantified by combining single regional input-output datasets with multi-regional input-output datasets.