Study And Case Analysis On Regional Land Carrying Capacity

Land carrying capacity can be defined as the super-threshold value of the scale and intensity of human activities which supported by land in a given period,a certain domain of rock mass,a certain social,economic and ecological environment,and it can be characterized by population and GDP.Because of the limited field area,the population is competing with GDP on the demand for land,and a population size corresponds to a GDP threshold.Under the development trend of our country’s population,the population of the region is predictable and variable,so we can calculate the maximum size of the economy the land can support on the basis of a certain population size.Based on the composition of the GDP,the comprehensive model framework of the economic part of the land carrying capacity is set up.In order to reification model and relate the land area and the economy,the paper introducing the parameter of land economy output rate.The comprehensive model includes population,crop output,consumption level,land economy output rate,etc.The calculation methods and models of these parameters can be sub models of the comprehensive model.Because the methods or models for parameter values are optional,and each of these will have a large effect on the results of the comprehensive model,the paper puts the focus on the model selection,precision verification and error transfer to study reliability of the results of model calculation,and finally,we can get the maximum amount of GDP that the area can support,and its 95%confidence interval under a certain population size in a target-year.Industrial land have the most impact in the land economic carrying capacity,an optimum redistribution to main industries of industrial land can enhance the land economic carrying capacity efficiently.In order to screen the main industries,the paper selected six indexes from industrial development,utilization of land resources and ecological environmental protection,then build up the calculating formula so that get the largest industrial added value,and emission intensity of COD、NH3-N、SO2、NOx are the constraint conditions,the result of the calculating formula is the result of optimal redistribution.Taking Yangzhou as an example,the result shows:(1)The population supported by land is 464.9087 ten thousand in Yangzhou in 2020,and the 90%confidence interval is 464.1210～465.696 ten thousand.In order to support the population in a high level of food consumption,the minimum demand for agricultural land is 1862.68 km~2,so that the maximum demand for construction land is 3638.06 km~2,the new available construction land is 686.86 km~2.With current development trend,the agricultural economic output will be 7.51x 106 yuan/km~2 and the construction land economic output will be 3.9668×108 yuan/km~2,the land economy carrying capacity will be 1.4571×1012 yuan,2.5027 times much more than the figure which with the current area distribution.The 90%confidence interval is 1.4188×1012～1.4954×1012 yuan.(2)According to the comprehensive ordering of the percentage of industry output value in gross value of industrial output,the rate of growth in industrial production,the industrial output per unit area,the rate of growth in industrial output per unit area,the SO2-emission efficiency,the NOx-emission efficiency,the COD-emission efficiency,the NH3-N-emission efficiency,the paper screen the 9 main industries:the electric equipment and machinery,the automobile industry,the special equipment,the computer,communications and other electronic equipment manufacturing industry,the metal products,the ordinary machinery,the industry of colored metals smelting and pressing,the chemical raw materials and chemical products manufacturing,the other Manufacturing.Under the constraint conditions of less than the emissions of COD,NH3-N,SO2,NOx in 2015,the paper redistribute the new available construction land.The industrial land economy carrying capacity is 1.9287×1012 yuan while the area is 686.86 km~2,the industrial land economy carrying capacity is 1.5584×1012 yuan while the area is 555.00 km~2,the industrial land economy carrying capacity is 1.1469×1012 yuan while the area is 408.45 km~2.