Evolution And Overall Allocation Of Physical Water-virtual Water Flux In Beijing

In recent years,with the rapid development of economy and society and the continuous improvement of trade marketization,the virtual water flow associated with inter-regional trade has exerted a profound influence on the water circulation law and water resource allocation system in the basin.At present,with the simultaneous growth of regional physical water consumption intensity and virtual water trade flux,the "two-dimensional and ternary" coupling flow pattern of physical water and virtual water has become the main feature of regional "nature-economy-society" water resources evolution.As one of the megacities with severe water shortage in China and even in the world,the combination of physical water and virtual water has alleviated the pressure of water resources in Beijing to a certain extent.At present,the integrated regulation of regional physical water and virtual water is of great significance to guarantee ecological construction and high-quality social and economic development of resource-scarce cities.Based on this,this study analyzed the characteristics of physical water consumption and virtual water flow in Beijing in recent years by using the input-output model of water resources.Combined with the actual water resource pressure index(WSI)and the assumed water resource pressure index(WSI*),the influence of the combined input of physical water and virtual water on the local water resource system was evaluated.A regional physical watervirtual water regulation method framework was put forward and a joint allocation model of physical water-virtual water was constructed.The optimization scheme of overall regulation of physical water-virtual water at the current level is analyzed,which provides scientific reference for water resources planning and industrial water-suitable development in Beijing in the new era.The main research contents and conclusions of this paper are as follows:(1)Based on the water resources input-output model,this paper analyzes the physical water consumption and virtual water flow in Beijing from 2001 to 2018.The results show that in terms of physical water,the total physical water consumption of the city showed a trend of decreasing first and then increasing,which was 3.94 billion m3 in 2018.The continuous optimization of water supply structure,the increasing proportion of reclaimed water and transferred water,and the decreasing proportion of agricultural and industrial water are conducive to relieving the pressure of local water resources and improving the utilization efficiency of water resources.In terms of virtual water,the input state of Beijing’s virtual water has always been present,and the total amount of input is constantly increasing,reaching 3.512 billion m3 in 2012,mainly with the input of agricultural products and related industrial products as the carrier.With the continuous adjustment of industrial structure,the industries with high water consumption and low water efficiency are gradually withdrawn.It is expected that the virtual water flux with agricultural products and high water consumption industrial products as carriers will continue to grow in Beijing in the future.(2)In this paper,WSI and WSI* were used to evaluate the impact of the combined input of physical water and virtual water on the local water resources system in Beijing.The results show that WSI * is always greater than 1,indicating that if there is no input of external physical water and virtual water,relying only on the local water resources in Beijing is far from meeting the rigid water demand of Beijing,and it is more difficult to support the sustainable development of social economy in Beijing.The study found that the difference between WSI and WSI* in 2012 was 58% higher than in 2002,indicating the increasing importance of external physical and virtual water investment in alleviating and improving regional water scarcity.It can be seen that the combined deployment of physical water and virtual water not only reduces the water pressure in Beijing,but also promotes the economic development and industrial quality and efficiency of Beijing,and plays an important role in ensuring regional water security.(3)Based on the "two-dimensional ternary" coupling flow theory method of regional solid water and virtual water,a framework of integrated regulation method of solid water and virtual water was proposed,aiming at the regional virtual water equivalent supply and demand balance.Based on this,the overall allocation model of physical water and virtual water in Beijing is constructed.Complex adaptive system theory is introduced to describe the flow and transformation of water resources among different water users in social and economic systems.The behavior of water users is further generalized into water-saving and efficient-enhancing behavior,virtual water trade behavior and physical water diversion behavior.The main body model is used to describe the economic,environmental and social benefits brought by the main body’s water use behavior,and an optimization model with comprehensive consideration of the economic,environmental and social benefits is established to realize the overall and optimal allocation of regional physical water and virtual water.(4)Based on the established physical water-virtual water system allocation model,the overall allocation pattern and optimization scheme of physical water-virtual water in Beijing under the current conditions were analyzed.The comparative analysis between the allocation optimization scheme and the actual water consumption status shows that,when the regional virtual water equivalent supply balance is guaranteed,the real water-virtual water optimization scheme increases the profit per unit water resource investment of the whole city by 86.7 billion yuan.The main reason for this is that more local physical water resources are flowing into more efficient service industries,while local agricultural and industrial demand is more satisfied by external virtual water diversion.The research shows that the water management concept of physical water-virtual water overall allocation brings new ideas for water security in resource-deficient cities,can better optimize the flow pattern of water resources among various industries,and is of great significance to improve the comprehensive benefits of regional water use.