Preliminary Calculation And Structural Analysis Of China's Marine Equivalent Virtual Water

Water resource is the foundation of regional social and economic development.However,the global water resources are limited and the regional distribution is uneven.Especially after the industrialization,the rapid economic development is intensifying the global water crisis.China is a big water user,and the contradiction between water supply and demand is very prominent.Since the reform and opening up,the development of the coastal zone has promoted the agglomeration of economic elements.Over the past decade,70%of the nation's population and 60%of its economy are supplied by 14%of the total water resources in China's coastal regions.Water shortages are particularly acute.In recent years,the concept of virtual water has been put forward.Domestic and foreign scholars began to explore ways to solve the water resource problem from the perspective of economic management.It was found through literature review that terrestrial products and services have been the focus of virtual water research up to this point.There have been few studies in this field on the ocean.However,as a vast reservoir of resources,the ocean can provide a variety of services for the land and relieve the pressure on the land.Under the background of land and sea coordination,this study focuses on the ocean,which occupies 97%of global water bodies.Taking the coastal areas of China as the research region,the replenishment capacity of marine products or services for terrestrial freshwater resources are explored in the process of marine development and utilization.Firstly,this paper reviews the related research of virtual water.CiteSpace,a visual analysis software,is used to analyze the research perspective and its relevance of virtual water at home and abroad.Based on virtual water theory,a new concept of“marine equivalent virtual water”is proposed.According to the idea that products and services in the same function between the sea and land can be converted equivalently,“marine food equivalent virtual water”,“marine environment equivalent virtual water”and“marine energy equivalent virtual water”are put forward from the perspectives of food,wastewater purification and power generation.The concept of each part is defined and the connotation attribute is analyzed.Meanwhile,the calculation formula of each project is presented and the content is calculated.The calculation results show that the total amount of China marine equivalent virtual water is U-shape trend.It falls from 18.2 billion m~3 in 2006 to 14.5 billion m~3 in 2011,and then rises to 16.7 billion m~3 in 2015.During the study period,the content of marine equivalent virtual water occupies the proportion of water consumption to reach 6.25%.Secondly,the structural characteristics of China's marine equivalent virtual water are analyzed from the national and local scales.From the perspective of national scale,the structure of marine equivalent virtual water is transformed from 54:45:1 to 75:21:4.From the perspective of space,the content of marine equivalent virtual water and its composition all present the skewness distribution characteristics,showing high and low interphase,south more than north less.The spatial differences are significant.From the perspective of local scale,the changes of marine equivalent virtual water in China's coastal 11 provinces and cities can be divided into three types:sharp drop-slow rise type,slow drop-slow rise type and fluctuation slow rise type.Finally,the content of marine equivalent virtual water structure is forecasted for China's coastal areas by 2025,using the prediction model of gray metabolism GM(1,1).The entropy value of the system is calculated from 2006 to 2025.According to the change of system entropy,China's marine equivalent virtual water system is divided into three types.Among them,the equilibrium development model mainly based on entropy increase.Many of these are provinces with rich marine resources or well-developed marine economies.The marine equivalent virtual water systems develop well.The orderly development model mainly based on entropy decrease.These are areas with relatively weak marine economies,it is difficult for various projects to develop comprehensively.The change development type shows the trend of entropy increase before entropy decrease.There is an obvious change in dominant type in the marine equivalent virtual water system.According to the variation characteristics of the marine equivalent virtual water in various provinces and cities,this paper puts forward some policy suggestions.