Virtual Water Flow Pattern Of Crops And Optimal Regulation Of Planting Structure In Henan Province

Water resources is one of the most important natural resources to ensure human normal life and maintain the normal operation of society.With economic development and population expansion,the contradiction between supply and demand of water resources gradually restricts the sustainable development of economy and society.The proposal of virtual water and water footprint expands the cognitive category of human beings on water resources.By calculating the trade and consumption of virtual water,a wider range of optimal allocation of water resources can effectively alleviate the pressure of regional water resources.Therefore,virtual water and water footprint theory are increasingly applied to the formulation of regional water resources management policies.China’s agricultural water consumption accounts for more than60%of the total water,and the imbalance between supply and demand of water resources is more prominent in agriculture.Excessive agricultural water consumption puts great pressure on regional water resources supply,improving agricultural water efficiency and reducing the water footprint per unit crop production play an important role in the sustainable development of agriculture.Therefore,this paper chooses to carry out the research on the virtual water flow pattern of crops and the optimal regulation of crop planting structure has important theoretical significance and practical value.Taking Henan Province as the research object,this paper selects eight crops of wheat,corn,rice,beans,oil,cotton,vegetables and potatoes,calculates the production water footprint of main crops in the region from 2006 to 2019,analyzes its temporal and spatial distribution characteristics,and analyzes the influencing factors of total water footprint of crops based on principal component analysis.Based on the production and consumption data of main grain crops in 31 provinces and regions in China,the minimum transportation cost method is used to calculate the grain trade between Henan Province and other provinces and regions,and the virtual water trade pattern of main crops in Henan Province is analyzed.Combined with STIRPAT model,ridge regression analysis is used to explore the driving factors of virtual water flow of crops in Henan Province;Build a multi-objective optimization model to explore the regional optimal planting structure adjustment scheme under the maximization of economic objectives,intensive and economical utilization of water resources and food security in Henan Province.The main research results and conclusions of this paper are as follows:(1)Based on the Water Footprint Evaluation Manual,the temporal distribution law and spatial pattern of water footprint per unit yield of crops in Henan Province from 2006 to 2019are analyzed.The results show that the average annual water footprint per unit production of the eight crops is cotton,beans,oil,rice,wheat,potato,corn and vegetables from large to small.In time,the water yield footprint of each crop shows a downward trend,and the areas with large water yield footprint in space are concentrated in the West and south of Henan Province.(2)The temporal and spatial distribution characteristics of the total water footprint of eight main crops from 2006 to 2019 were calculated and analyzed,and the influencing factors of the total water footprint were analyzed by principal component analysis.The results showed that the total annual water footprint of the eight crops was wheat,corn,vegetables,oil,rice,beans,cotton and potato from large to small.In terms of time,the total water footprint of wheat,corn,rice and vegetables shows an upward trend,while the total water footprint of beans,oil,cotton and potato shows a downward trend.In terms of space,the areas with high total water footprint are concentrated in the central and southern part of Henan Province.The first and third principal component factors affecting the total water footprint are mainly crop planting area,and the second and fourth principal components are mainly meteorological factors.(3)Based on the minimum transportation cost method,the virtual water flow structure and spatial pattern of crops in Henan Province in 2019 are analyzed,and the driving mechanism of virtual water output is discussed by using the extended STIRPAT model.The output of wheat and Maize in Henan Province is large,and the output of wheat and oil is large;The outflow of rice and oil is small,and the virtual water output is small,which is mainly determined by the difference of planting area of each crop.The model selects population index,economic development index and agricultural technology level index as independent variables,and the virtual water output of main crops from 2011 to 2019 as dependent variables.The results show that the positive driving factors of virtual water output in Henan province include population,per capita mechanical power,sowing area and the proportion of primary industry,and the negative driving factors include per capita GDP,residents’consumption level,the proportion of tertiary industry and urbanization rate.(4)The multi-objective optimization model was used to explore the optimal planting structure of eight crops in Henan Province.The objective function of the model includes the maximum economic benefits and the minimum blue water footprint.Constraints include cultivated land area constraints,agricultural available water constraints,food security constraints and minimum demand constraints for vegetables.The results show that the planting area of wheat,corn,rice,beans,oil,cotton,vegetables and potato after adjustment becomes5.51 million hm~2,4.17 million hm~2,0.47 million hm~2,0.14 million hm~2,1.3 million hm~2,10000hm~2,1.88 million hm~2 and 0.52 million hm~2.Economic benefits increased by 18.7 billion yuan;The blue water footprint of eight crops decreased by 1.0 billion m~3;The grain trade volume decreased by 2.49 million tons,and the virtual water flow embedded in crops decreased by 1.6billion m~3.