Evaluation And Analysis Of Ecological Carrying Capacity Of Huainan City Based On System Dynamics

China is now the world's largest producer and consumer of coal.The coal industry plays an important role in social and economic development.But coal consumption in the proportion of energy gradually declined.For the resource-oriented city with a single development mode,it faces an urgent task of transformation and upgrading.As a coal resource-based city,Huainan city's primary task is to seek new growth points,realize urban transformation and sustainable development.In addition,the urban ecological carrying capacity is an important basis to measure the urban sustainable development capacity.Therefore,it is of great practical significance to evaluate and improve the urban ecological carrying capacity for the economic transformation and sustainable development of coal resource-based cities.By using system dynamics,this paper systematically analyzes the components of urban ecological bearing capacity,and predicts and analyzes the urban ecological bearing capacity of coal resources.By sorting out the concept of urban ecological carrying capacity and combining with the development status of the research objects in this paper,four key factors that play a key role in urban development are selected.It is divided into four sub-systems: resources,ecology,economy and society to construct an evaluation index system of urban ecological carrying capacity.Mean-variance decision method was used to evaluate the bearing capacity and analyze the change trend between 2008 and 2016.Secondly,the Vensim DSS 5.8software was used to build the system model,and the sensitivity test was carried out to verify and modify it.According to sensitivity analysis,variable parameters were determined and four different future urban development schemes were set.They are the continuation of the status quo,economic restructuring,environmental protection and coordinated development.The dynamic simulation prediction and optimization of the four schemes are carried out.The main research results and conclusions are as follows:(1)Establish the ecological carrying capacity evaluation index system of Huainan city.Based on the analysis of the development status of coal resource-based cities and the influencing factors of ecological carrying capacity,the system is divided into four subsystems.It is resource subsystem,social developmentsubsystem,economy and technology subsystem,ecological environment subsystem respectively.According to the mutual relations between evaluation factors,26 evaluation indexes were selected to distinguish bearing pressure and bearing potential.Finally,the ecological carrying capacity evaluation index system of Huainan city was constructed.(2)Establish the dynamic model of Huainan city's ecological bearing capacity system.Based on the established evaluation index system of bearing capacity,the causality of each subsystem and its parameters is analyzed.The key structure diagram,causality cycle diagram and stock flow diagram were drawn,and the dynamic equation of the system was determined.Finally,the dynamic model of ecological bearing capacity system in Huainan city was established.Sensitivity test and correction were carried out to determine the variable parameters.In this way,four different future urban development plans are set up,namely,continuation of the current situation,adjustment of economic structure,environmental protection and coordinated development.The dynamic simulation prediction and optimization of the four schemes are carried out.(3)Based on the calculation results,the variation trends of the four subsystems from 2008 to 2016 were analyzed.Although the bearing capacity curve of the environmental subsystem fluctuates greatly,the overall bearing capacity curve shows an upward trend.In 2016,the bearing capacity index reached the higher state of0.8183.The bearing capacity of the resource subsystem has a relatively flat trend and steady growth,reaching a relatively intermediate level of 0.6800 in 2016.The bearing capacity of the economic subsystem fluctuated twice from 2008 to 2016.The former dropped from 0.1467 in 2008 to 0.0750 in 2009,and the latter reached the peak of the curve 0.6893 with an annual growth rate of 15.65% from 2009 to 2013.The index then fluctuates due to fluctuations in energy market prices.It stabilized at0.7090 in 2016 and was at a intermediate bearing capacity.The social subsystem has been steadily improving.From 2008 to 2015,the annual growth rate was 10.97%,rising from 0.0816 in 2008 to 0.8488 in 2015.However,in 2016,the bearing capacity index of the social subsystem showed a significant decline and stabilized at the standard score of 0.5770,indicating that social development was greatly affected by unstable factors.It is urgent to transform resource-oriented cities and improve their carrying capacity.(4)From the perspective of overall ecological carrying capacity,the ecological carrying capacity of Huainan city increased from 0.1659 to 0.6961 in 2008 to 2016.Its ecological carrying capacity has been greatly improved.In 2016,its ecological carrying capacity was at a relatively intermediate level.However,this is still far from the bearing capacity level required by sustainable urban development.Therefore,it is still necessary to take corresponding measures to improve the bearing capacity of each subsystem.According to the simulation prediction and optimization results of the coordinated development scheme,the ecological carrying capacity index of Huainan city in 2025 reached the advanced state of 0.9108.The best plan to improve the ecological carrying capacity of Huainan city in the future is the coordinated development plan.Because it can moderately control urban expansion and population size,improve the proportion of land use and ecological environment,optimize the structure of resource utilization and improve its utilization efficiency.Finally,it can gradually realize the coordinated and sustainable development of society,economy,energy and environment.