Influence Of Cultivated Land Use Change On Agricultural Water And Soil Resources Matching In Yangtze River Economic Belt And Its Optimal Regulation

Water resources and land resources are the core elements of agricultural production.With the increasing demand for water and soil resources,the mismatch of water and soil resources fundamentally restricts the process of agricultural modernization and is an important factor affecting food security and rural revitalization.The matching of water and soil resources reflects the quantitative relationship between agricultural water resources and cultivated land resources in a specific region,and reveals the suitable matching of water and soil resources in time and space,which is of strategic significance for regulating the utilization mode of agricultural water and soil resources,promoting the sustainable development of agriculture and ensuring food security.The Yangtze River Economic Belt is an important grain producing area in China.On the one hand,with the increase of population,urbanization and industrialization,the mismatch of water and soil resources has become a key factor restricting its efficient agricultural development.On the other hand,the situation that cultivated land resources are facing the difficulties of ecological conversion of farmland in the upstream,the large reduction of downstream area and the unbalanced spatial distribution further aggravate the risk of mismatch between agricultural water and soil resources,which is not conducive to the sustainable development of agriculture.Therefore,it is of great significance to analyze the influence of cultivated land use change on the matching of agricultural water and soil resources in the Yangtze River Economic Belt and to carry out the optimization of cultivated land layout to guide the direction of cultivated land use change and realize the sustainable development of agriculture.In order to solve the problems of insufficient consideration of agricultural pollution,ignoring the external influence of cultivated land use change on agricultural water and soil resources matching,and the optimization of water and soil resources matching only stays at the level of putting forward optimization strategies for cultivated land use,this paper introduces gray water footprint,constructs a water and soil resources matching index that takes into account both water quality and water quantity,and reveals the temporal and spatial pattern of agricultural water and soil resources matching in the Yangtze River Economic Belt.On this basis,the internal and external influence paths of cultivated land use change on the matching of water and soil resources are clarified,and the positive and negative effects of cultivated land use change on the matching of agricultural water and soil resources in the Yangtze River Economic Belt are explored through hydrological analysis.Finally,the linear programming model is used to optimize the layout of cultivated land use,and the positive impact of cultivated land use change on the matching of agricultural water and soil resources is the greatest.The results and conclusions of this research are as follows:(1)The matching pattern of water and soil resources in the Yangtze River Economic Belt presents obvious spatial differences,and the main problem of agricultural water and soil resources matching is water shortage.From 2000 to 2019,the matching of water and soil resources in the cities along the Yangtze River Economic Belt in Sichuan,Hubei and Jiangsu was relatively good,while the matching of water and soil resources in Hunan and Jiangxi was relatively balanced,and the matching of water and soil resources in most cities in Anhui,Jiangsu and Guizhou was relatively poor.The matching of water and soil resources in Hubei,Jiangsu,southern Anhui,Sichuan,Chongqing,Yunnan and other places is getting worse.The main problem in areas with poor matching of water and soil resources is water shortage.Water-deficient areas are mainly distributed in Sichuan,Hubei,Yunnan,Guizhou,Zhejiang and other places,among which severe water-deficient areas are mainly distributed in Sichuan and Hubei,while dual water-deficient areas and water-deficient areas are mainly distributed in Anhui and Jiangsu.(2)The change of cultivated land use in the upper reaches of the Yangtze River Economic Belt has a wide range and a large degree.The change of cultivated land use in most cities has a small internal impact on the matching of water and soil resources,while the middle and lower reaches of the Yangtze River have a large external impact.Judging from the comprehensive impact of cultivated land use change on water and soil resources matching,cultivated land use change in Sichuan and Hubei in the upper reaches of the Yangtze River Economic Belt has a greater impact on water and soil resources matching,while cultivated land use change in the middle and lower reaches has a similar impact on water and soil resources matching.Specifically speaking,the changes of cultivated land use in Ganzi Tibetan Autonomous Prefecture,Panzhihua City,Aba Tibetan and Qiang Ethnic Group,Xiantao City,Hubei Province,Yangzhou City,Jiangsu Province and other cities have great influence on the matching of water and soil resources,while the changes of cultivated land use in upstream Chongqing City and downstream Shanghai City have little influence on the matching of water and soil resources.From the internal impact of cultivated land use change on the matching of water and soil resources,it can be seen that the cities in the Yangtze River Economic Belt that have great internal impact on the matching of water and soil resources are mainly concentrated in Sichuan,Hubei and Jiangsu,while the changes of cultivated land use in most cities in Yunnan,Jiangxi,Zhejiang and Hubei provinces have little internal impact on the matching of water and soil resources;The change of cultivated land use in Sichuan,Chongqing,Hubei and Hunan in the middle and upper reaches of the Yangtze River Economic Belt has a great external impact on the matching of water and soil resources,while the change of cultivated land use in Yunnan,Jiangsu and Anhui has a little external impact on the matching of water and soil resources,and the areas with a great external impact are mainly concentrated in the middle and lower reaches of the Yangtze River.(3)The optimized cultivated land layout can effectively promote the coordinated development of cultivated land protection and water and soil resources matching,and guide the direction of cultivated land use change.The optimized layout of cultivated land takes precedence over the cities along the Yangtze River Economic Belt and the areas of Guizhou,Hunan and Jiangxi south of the Yangtze River to reduce cultivated land,while increasing cultivated land in the cities of Yunnan,Chongqing,eastern Sichuan,Hubei and northern Anhui.Increasing the city area of cultivated land has little negative impact on the matching of water and soil resources,while reducing the city area of cultivated land has a higher positive impact on the matching of water and soil resources.On the premise of the total balance of cultivated land,the Yangtze River Economic Belt has less reserve resources,and the changeable space of cultivated land is greatly limited.The three scenarios without reserve resources tend to lay out cultivated land in the middle and lower reaches.Guizhou,Hunan and Jiangxi in the south of the Yangtze River can provide space for the occupation of cultivated land,while Hubei,Jiangsu and Anhui in the north of the Yangtze River Economic Belt can provide space for the replenishment of cultivated land.With the improvement of the expandable space of cultivated land in the city,the number of cities that can increase cultivated land decreases,and the number of cities that can reduce cultivated land increases,and the positive impact of cultivated land use change will be greater.Therefore,in the process of cultivated land utilization,it is necessary to take targeted control measures according to the spatial characteristics of agricultural water and soil resources matching,the degree of influence of cultivated land use changes on agricultural water and soil resources matching,and the results of optimal layout of cultivated land.First of all,water-quality-oriented water-deficient areas need to reasonably control the input of production factors,water-oriented water-deficient areas need to pay attention to the adjustment of crop planting structure,and dual-type water-deficient areas need to rely on scientific and technological innovation and technological progress to reduce the risk of mismatch between agricultural water and soil resources;Secondly,in areas where the change of cultivated land use has a great influence on the matching of water and soil resources,the input of agricultural production factors can be reduced and the cultivated land area can be reduced appropriately;Finally,the results of the optimal layout of cultivated land use based on the matching of agricultural water and soil resources guide the direction of cultivated land use change,and it is clear whether the area can increase or decrease cultivated land.