| Water resources,land resources and food are important foundations for human survival,social stability,and economic development.They are interdependent,mutually constrained,and influenced by each other with multiple causal relationships.Food security is the "largest of the country" and has long been an important strategic position in China.Conducting research on the Water-Land-Food Nexus is of great significance for promoting resources use efficient and ensuring national food security.This study took 2005-2020 as the research period,methods such as RS/GIS,DEA model,LMDI model,coupling coordination model,spatial analysis model,and obstacle diagnosis model were comprehensively used.Based on the analysis of the evolution characteristics of various elements of water resources,land resources,and food production,the study measured water and land resources utilization efficiency and food production efficiency,decomposed the water and land resources utilization effects of changes in food production,quantitatively evaluated the coupling coordination degree of Water resource-Land resource-Food production syste,and identified its main obstacle factors.The main conclusions are as follows:(1)The spatiotemporal evolution characteristics of Water-Land-Food related factors in China were analyzed.The total amount of water resources has shown a fluctuating upward trend,the water use structure has gradually become reasonable,and the number of cultivated land has shown a slow downward trend.Through less agricultural irrigation water consumption and cultivated land,China has produced more food,and the status of staple food is increasingly valued.The uneven spatial pattern distribution of water and cultivated land resources continues.In arid and semi-arid regions,food production relies on irrigation.On the raster scale,precipitation in farmland ecosystems is increasingly divided into evapotranspiration,and the scale of cultivated land type conversion has increased significantly in recent years.A series of planting technology changes and the application of sustainable green development models have shown a positive impact on grain potential productivity as a whole.(2)Water and land resources utilization efficiency and food production efficiency were measured.The overall efficiency of water and land resources utilization in different regions fluctuates greatly,with a change rate ranging from-0.0315/a to 0.0144/a.In most regions,the efficiency of development is higher than the efficiency of economic benefit transformation,which is becoming a weak link in China’s water and land resources utilization.During the research period,the average pure technical efficiency of food production was always lower than the average scale efficiency of food production.It appears that the improvement of food production efficiency in China mainly benefits from the expansion of production scale and large input of factors.Except for the periods 2008-2009 and 2013-2014,China’s total factor productivity of food production has been on the rise in other times.From the perspective of total factor productivity change index of food production and its internal composition in different regions,more than half of the provinces belong to the type of comprehensive improvement in food production efficiency evolution.(3)The contribution rate of water and land resources utilization effects of food production changes was clarified.From the perspective of water resource utilization,the effect of irrigation output value is the leading factor affecting the changes in China’s food production,with an overall contribution rate of64.57%.Developing efficient and water-saving irrigation techniques,optimizing field management measures,and increasing the unit consumption of aquatic grains are the main ways to achieve food yield increase.From the perspective of cultivated land resource utilization,the cultivated land area effect has a negative impact on China’s food yield growth,with the grain yield per unit area effect,grain cropping ratio effect,and multiple cropping index effect all having a positive impact,with the overall contribution rates of 46.12%,6.69%,and 32.05%,respectively.From the perspective of crops,there are significant differences in the yield per unit area effect and the planting structure effect among various crops in China,while the variation rules of the grain cropping ratio effect,the multiple cropping index effect,and the cultivated land area effect are basically similar among various crops in China.(4)The comprehensive evaluation index system and analysis method for Water resource-Land resource-Food production system coupling and coordinated development were proposed.Based on theoretical basis and relevant literature research,a comprehensive evaluation index for Water resource-Land resource-Food production system coupling and coordinated development is determined.The evaluation indicators are combined and weighted using entropy method and coefficient of variation method.Combining the comprehensive development index model and the coupled and coordinated degree model,the measurement of the comprehensive development level of subsystems,composite systems,and system coupling and coordinated development level is achieved.The results showed that the annual average level of the comprehensive development index of water resource subsystem in 31provinces(cities,autonomous regions)is between 0.245 and 0.632,the annual average level of the comprehensive development index of land resources subsystem is between 0.203 and 0.418,and the annual average level of the comprehensive development index of food production subsystem is between0339 and 0.597.The comprehensive development level of land resources lags behind the comprehensive development level of water resource and the comprehensive development level of food production.The comprehensive development level of China’s Water resource-Land resource-Food production complex system has shown an upward trend.(5)The spatiotemporal characteristics of the coupling and coordinated development level of Water resource-Land resource-Food production system were revealed,and its main obstacle factors were identified.The system coupling coordination degree of 31 provinces(cities,autonomous regions)ranges from 0.538 to 0.754,involving forced coupling coordination types,primary coupling coordination types,and intermediate coupling coordination types.The level of coupling and coordination development in each region has evolved to a coordinated development stage,and the spatial agglomeration characteristics are obvious.High high types are mainly concentrated in the eastern coastal areas,and low low low types occupy more provinces.The main obstacles to the coupling coordinated development of China’s Water resource-Land resource-Food production system include per capita disposable income of rural residents,per capita grain production,and soil erosion control rate.In recent years,the negative impact of the ecological environment has gradually emerged.The main innovation points are as follows:(1)Starting from the relationship between water resources,land resources,and food production,a relatively complete research method for the relationship between Water-Land-Food has been established.(2)The efficiency and decomposition factors effects of Water-Land-Food association were measured,and the internal interaction rules between water resources,land resources,and food production were clarified.(3)The indicator system and evaluation method for the coupling and coordinated development of Water resource-Land resource-Food production system were designed,and the spatiotemporal differences and evolution characteristics of the coupling and coordinated degree of Water-Land-Food system in 31 provinces(cities,autonomous regions)in China were proposed. |
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