Coupling Research On Water-food Relationship Of Ecosystem Services Based On System Dynamics

Water resources and food are the most important and basic resources of human beings and society.In recent decades,due to various factors such as global population and economic growth,changes in human lifestyles,and global climate change,human demand for water resources and food has continued to increase.As a result,the shortage of water resources,the deterioration of aquatic ecosystems and the related re-shocks of other ecosystems have become the main challenges facing the world,and the food shortages closely related to them have also become global resource issues.In this context,the significance of exploring the water-food relationship of ecosystem services is becoming more and more significant.At the same time,it is especially important to study the impact of changes in population and economy on the supply and demand of water resources and food in the ecosystem.Therefore,this article tries to explore the relationship between water and food in ecosystem services of the Jinghe River Basin and provide scientific reference for the optimization of the spatial pattern of ecosystem services in the Jinghe River Basin.The main research contents of this paper are as follows:The SWAT model and the spatial model of food production are used to quantitatively evaluate the water supply resources and food supply in the Jinghe River Basin from 2000 to 2015.Based on statistical data,the water demand and food consumption of the Jinghe River Basin in 2015 are spatialized.Based on this,two indicators of water supply-demand ratio and food self-sufficiency rate were introduced to reflect the supply and demand situation of water resources and food in the Jinghe River Basin in 2015.According to the above-mentioned processing process of supply and demand on water resources and food,this paper introduces a system dynamics model,using spatial population data and economic data as a link,to establish a causal relationship circuit diagram of ecosystem services that conforms to the actual water-grain relationship in the Jinghe River Basin.The system dynamics model of watershed ecosystem services is presented.Then use the model to analyze the changes in the water supply-demand ratio and the self-sufficiency rate of food to explore the coupling mechanism of water-food relationship in the ecosystem services of the Jinghe River Basin.Based on the recent development of the Jinghe River Basin,nine different population and economic development scenarios are set up to simulate the development of the ecosystem-serving water-food relationship in the River Basin in 2030.(1)The differences in spatial distribution of water resources and food supplies in the Jinghe River Basin are obvious,and they are increasing in time.Water supply services increased from 2000 to 2015 as a whole.The areas with abundant supply were concentrated in the middle and lower reaches of the south,with loess remnants,mountain forests,and Mountain Rivers.It is mainly distributed in the southern areas of Chongxin County and Xichuan County of Pingliang City,Lingtai County,Fengxiang County of Baoji City,Changwu County,Bin County and Xianyang County of Xianyang City.The overall food supply in the Jinghe River Basin mainly shows an increasing trend.Although the high supply value has become smaller,it is widely distributed and concentrated in the lower reaches of the south,mainly in Baoji City and Xianyang City.(2)In 2015,the water supply-demand ratio and food self-sufficiency rate in the Jinghe River Basin were different in the upstream and downstream areas.The supply-demand ratio of water resources was higher in the middle and upper reaches of the northern and eastern parts of the river basin,as well as in some parts of the lower reaches of the Jinghe River Basin,such as Xichuan County and Lingtai County,reaching up to 3.52551.That is to say,the supply and demand of water resources in these areas is relatively good and can meet the demand for water resources.However,the water supply in the northernmost part of the basin,the western mountainous region,and the mountainous region in the southeast cannot meet the demand.Food self-sufficiency rates are high in parts of Dingbian County,Huachi County,and Huanxian County,Yanchi County,and Fengxiang County,Xunyi County,and Chunhua County in the lower reaches of the river basin,with a maximum value of 3.69666.The areas with poor self-sufficiency are mainly distributed in the loess remnants in the middle of the basin.(3)Coupling the water-food relationship between ecosystem services in the Jinghe River Basin,and found that changes in the ratio of water supply and demand and the rate of self-sufficiency in food interact with each other,showing a clear synergistic relationship.(4)Introduce system dynamics model,construct a causality circuit diagram of the ecosystem services in Jinghe River Basin under the water-food relationship,and establish a system dynamics model to simulate the development of ecosystem services in Jinghe River Basin.The main features of this paper are:(1)With the help of system dynamics models,water resources and food supply and demand are combined with population and economic data through two indicators of water supply and demand ratio and food self-sufficiency ratio,and ecosystem services are connected to human society.(2)Set scenarios of population and economic development at different development rates to predict the supply and demand of water resources and food in the river basin,and fully consider the impact of human and social factors of population development and economic development on water resources and food security in the Jinghe River Basin.