| Rapid economic and social development has resulted in human demand for resources that has outstripped the supply of the natural environment,and resource and environmental problems have become increasingly prominent.The appropriation of natural capital stock and the depletion of natural capital flow are the core issues of sustainability debate.As a key natural capital,freshwater resources have irreplaceable functions:source function(direct provision of freshwater resources for humans),sink function(ability to neutralize waste emissions without causing ecological changes),life support(maintenance of ecosystem function and healthiness)and function to provide health and well-being for humans.With the development of society and the improvement of human living standards,the increasing demand for water has become a major challenge for sustainable economic and social development.The agriculture is the sector that uses the most water and also has the greatest potential for water conservation.The three-dimensional water footprint model is suitable for assessing the sustainable status of regional freshwater resources,distinguishing between the appropriation of freshwater resource flows and stocks,and measuring the intra-and inter-generational equity of water resources utilization,but the current three-dimensional water footprint model and its application are still not perfect.Based on the theory of 3D water footprint,this paper improves the existing 3D water footprint model from two perspectives of water quality and quantity;takes the agricultural water use of 31 provinces in China from 1998to 2020 as the research object,adopts a bottom-up approach to account for the amount of available freshwater resources at the provincial level,and adopts a grandfathering method to allocate it to the agricultural sector,and analyzes the spatial and temporal evolution characteristics of the 3D water footprint of Chinese agriculture;adopts Cluster analysis and other methods were used to assess the sustainability of regional agricultural water use,and to quantify the decoupling between the three-dimensional agricultural water footprint and economic development,and to propose measures for the sustainable development of regional agricultural water use based on this.The main research progress achieved is as follows.(1)The concept,connotation and evaluation model of 3D water footprint have been improved.Combining water footprint theory and ecological economics theory,the basic concept and scientific connotation of 3D water footprint were improved and developed as an indicator for assessing freshwater resources using intra-generational equity and inter-generational equity.The improved 3D water footprint is able to consider the expression of both source and sink functions of freshwater resources,and is superior to the 2D water footprint in terms of indicators,structure and function.(2)The spatial and temporal differences in China’s agricultural water footprint were large,and the amounts of freshwater resources available for agriculture was the same as the change in annual precipitation.The annual average value of China’s agricultural water footprint from1998 to 2020 was 3342.5×10~8m3,and the change in agricultural water footprint varies widely among provincial administrative regions,and the overall agricultural water footprint showed a significant decreasing trend over time.The change trend of China’s agricultural available water resources was roughly the same as the change trend of annual precipitation.The spatial distribution of the regional average arable agricultural water availability per mu showed the distribution characteristics of the most in southwest China and the least in north China.The temporal changes showed the largest decrease in Inner Mongolia and the largest increase in Shanghai,both of which were closely related to the interannual differences in regional precipitation.(3)The spatial distribution of China’s agricultural 3D water footprint varies significantly,and the overall trend of agricultural water use sustainability becomes better.At the provincial level,unsustainable agricultural water use was mainly distributed in northern,eastern and northwestern China.Agricultural water footprints were more extensive at the provincial level,mainly in South China and Southwest China.China’s agricultural water surplus rate remains between 50%and 60%,but due to the spatial and temporal uneven distribution of China’s water resources,the spatial and temporal variability of agricultural water surplus and deficit is also large.It is recommended to balance the regional water resources allocation,adjust the crop cultivation structure,and optimize the inter-regional crop circulation brought by(4)The clustering results reflect that the overall agricultural water use in China tended to deteriorate,and the agricultural water-economic types vary widely over time.The spatial distribution of agricultural water clustering results showed that the sustainable status was better in Central,South and Southwest China,while the opposite was true in North,East and Northwest China.In the temporal changes,the number of provincial administrative regions located in the lightly utilized water resources and lagging water resources stock types remainede basically the same,decreasing from 25 in 1998 to 24 in 2020,and the number of provincial-level administrative regions with lagging water resources was decreasing.The changes in Xinjiang were especially obvious,from the light utilization of agricultural water resources to the heavy utilization of water resources.In the classification of agricultural water-economy types,the overall agricultural water-economy relationship in North China was poor,and some area of agricultural water-economy relationships in Northwest,Central China,East China and Northeast China were poor.At the provincial level,Zhejiang was the best and Beijing was the worst.After 2014,the agricultural water-economy types in Beijing and Shanghai had further deteriorated.China’s agricultural water use had been already in the right half of the Kuznets curve,which the agricultural water footprint decreased with economic development,but the resistance to decline in the agricultural water footprint with economic growth increased,and agricultural water conservation technologies need to be developed and irrigation management improved to enhance irrigation water utilization and utilization efficiency to help achieve a decoupling relationship between regional agricultural water use and economic development,thereby forming a virtuous cycle between environmental and economic development.This will create a virtuous cycle between environmental and economic development. |
