台灣虛擬水貿易的角色: 多區域投入產出分析

Abstract

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International trade plays a key role for achieving food security. However, as commodities are traded, the virtual water embedded in these commodities are also traded. In this paper, it is argued that agricultural imports not only help achieve food security, but also alleviate water scarcity. This study provides a virtual water extension of the World-Input Output Database (WIOD) 2016 release, consisting of three types of virtual water, namely green, blue, and grey, from 2010 to 2014 of 43 countries. As for Taiwan, its actual blue water data is included in the database, instead of estimations. As an application, a multiregional input-output (MRIO) analysis at both national and sectoral levels is conducted for Taiwan, which in 2021 faced its worst water shortage in the past 56 years. The overall virtual water consumed by Taiwan increased by 12% from 2000 to 2010, and as expected, Taiwan, in all types of water is a virtual water importer and is most dependent on imports of green virtual water. There is also an observed increase in blue agricultural virtual water exports. It is suggested that it may be better to decrease the blue virtual water exports instead of increasing it, so that the virtual blue water exported abroad may be reallocated to other sectors that may be in need and that would be able to generate greater productivity than the agricultural sector, particularly under water scarcity conditions. Lastly, the relationship between trade openness, food self-sufficiency, and food security index is described, wherein it is asserted that increased agricultural imports improve both food security and water scarcity conditions.