Analysis Of Virtual Water Flow Network Structure And Invulnerability In China's Major Crops

Global food security issues and water crisis are affecting regional sustainable development.The impact of various factors such as climate change,natural disasters,and wars has made the contradiction between supply and demand of water resources increasingly prominent.In particular,the shortage of water for agriculture has caused more and more countries to rely on trade imports to ease the pressure on food supply.China's agricultural water consumption in recent years has continued to exceed 60%,exacerbating the water shortage crisis.Although agricultural product trade has effectively eased regional food supply pressures,it has neglected the impact of the flow of hidden factors in the trade process on regional ecological security.The proposal of virtual water and related theories will expand the scope of agricultural water use,and provide new ideas for solving food security and water security.However,the existing research on virtual water has largely focused on the calculation of virtual water flow between regions,which seems that the related research has reached a deadlock in shallow quantitative research.Therefore,from the perspective of network structure,this paper studies the characteristics and stability of China's virtual water flow network,and simulates the network's invulnerability when subjected to different blows.This paper combines the ecological network and complex network theory to analyze the characteristics and stability of the virtual water flow network of major agricultural products.From 2000 to 2017,China 's virtual water flow continued to increase,but the network system 's channel capacity decreased,system polymerization degree and redundancy degree decreased,system usage rate decreased,and idleness rate increased,indicating the decline of the stability of China 's main agricultural product virtual water flow network.The weakening of anti-interference and buffering capabilities reveals China's potential contradiction between supply and demand of virtual water.The regions with greater in-node degree are distributed in more economically developed regions,and those with greater out-node degree are in the major food supply areas;the node strength varies greatly between regions,and the high variability in node degree and node strength reveals the fragility of the virtual water flow network structure;the heterogeneous characteristics of the node correlation degrees,indicating the situation of virtual water connected between regions.At the same time,the weight of the network is given based on the virtual water flow in the link,and the structural characteristics of the virtual water flow weighted flow network are explored to give practical significance to the network research.The network research method analyzes the characteristics and stability of the virtual water flow network,which lays the foundation for the study of the network's invulnerability characteristics later.Afterwards,the importance of nodes was evaluated using the node degree and betweenness centrality.Simulating the changes in the network's invulnerability indicators under random attacks and deliberate attacks,it was found that the node attack strategy under deliberate attacks is more destructive to the network,and the network structure will quickly disintegrate.Such an attack can cause the collapse of the network,and the removal of key nodes occupying important positions in the network more easily destroyed the network structure.That is,the areas with more input/exit trade partners or a greater influence in the network have a more significant impact on the network's anti-destructive performance due to their important connectivity or hub characteristics,and nodes with trade volumes amplify the influence on the network's invulnerability and impart practical significance in a real network,thus confirming the destructive force of deliberate attacks on the network.It is inspiring to protect key nodes in the network preferentially to prevent the collapse of the network structure.The invulnerability research undertakes the network stability research and serves as the foundation for the optimization and control of the virtual water flow network and the adjustment of the regional crop planting structure,with a view to providing a reasonable reference for national and even global food and water security.