中国区际间主要农产品虚拟水流动格局稳定性

为分析中国区际间虚拟水流动格局的稳定性及为将来研究虚拟水流动格局维持机制提供理论依据，通过构建1999-2010年中国区际间主要农产品虚拟水流量关系矩阵，引入生态网络安全系统相关概念，构建虚拟水流动格局网络稳定性模型，结果表明：东北、黄淮海和长江中下游地区是中国虚拟水的主要调出区；其他区域是调入区；虚拟水流动格局网络系统的信道数目减少，信道容量逐年降低；系统聚合度和系统冗余度亦呈波动降低趋势；系统网络使用率呈现降低趋势；系统网络空闲率呈增加趋势；网络系统指标表明中国区际间主要农产品虚拟水流动形成的网络系统稳定性逐年降低。最后，提出建立粮食安全预警系统等5方面应对措施。

Research on pattern sability of virtual water flow embedded in major crops trade among regions in China

Virtual water strategy has become a research focus of modern water science. According to traditional virtual water theories, virtual water should flow from regions rich in water to those poor in it. However the flowing direction of virtual water in China is from the north to the south, This paper constructs the virtual water flowing matrixes embedded in the major crops between 1990-2010 among eight regions of China, and builds the model for assessing the network system stability based on the related concept and method of the ecological network security system. This paper reaches such conclusions that: (1) the three regions of Northeast China, Huang-Huai-Hai plain and the middle and lower reaches of the Yangtze River are the main net virtual water export area, while the other five regions are the net import area in China, and the virtual water flowing quantity tends to increase; (2) the channel number of network system of virtual water flowing pattern decreased from 26 in 1999 to 24 in 2010, and the channel capacity was reduced from 2.3676 in 1999 to 2.0171 in 2010, which shows that the network system environment was degraded; (3) the polymerization degree of network system decreased from 1.0456 in 1999 to 0.7614 in 2010, which reflects the fact that the interdependency degree among eight regions was weakening; (4) the redundancy of network system decreased from 1.3221 in 1999 to 1.2557 in 2010, and the usage rate was decreased from 0.4416 in 1999 to 0.3775 in 2010, while the idleness rate was increased from 0.5584 in 1999 to 0.6225 in 2010, which reflects the fact that the optional paths of network system were decreased and the anti-interference capacity of network system was weakening. The network system indexes mentioned above show that the stability of the system is abating year by year. Finally, five measures are suggested to be taken: (1) set up the early warning system of food security; (2) strengthen the ability of food product, circulation and conservation; (3) promote the international strategy of food security; (4) constitute practical virtual water strategy; (5) establish the agricultural ecology compensation mechanism.