Urban Water Supply And Demand:System Dynamic Model And Simulation Based On Production Function

The complex influence of economic development and social progress leads to the imbalance of supply and demand of urban water resources.In order to meet the requirements of building a water-saving society with sustainable development that put forward in the 13th five year's plan of China,this paper combines the production function with system dynamics to establish an optimization model for the supply and demand of industry,domestic and comprehensive water.When using the production function to calculate the water supply and the depreciation of fixed assets,the straight-line depreciation method and accelerated depreciation method are compared and analyzed.We hope to optimize the supply and demand management of urban water resources.Taking Suzhou as an example,this paper compares the supply and demand differences under different combinations,and designs the corresponding response methods to find out the plans that meet the requirements of water-saving society and are suitable for the future sustainable development of the city.Firstly,in the industrial water supply and demand system,the industrial water demand function is expressed as the sum of the general industrial water demand and the power industry water demand,the industrial water supply function is expressed as the Cobb Douglas production function.Starting from the supply side,this paper discusses the reasonable value range and regulation mode of industrial water supply.Secondly,in the domestic water supply and demand system,the domestic water demand is obtained by adding the urban domestic water demand and the rural domestic water demand.The domestic water supply is expressed by the C-D production function which is different from the industrial water supply,changing Total Factor Productivity in C-D production function from fixed value to variable.From the demand side,it is assumed that different water use modes of urban residents are different,and corresponding countermeasures are designed.Finally,in the comprehensive water supply and demand system,the comprehensive water demand is obtained by adding the domestic water demand,industrial water demand,urban public water demand and agricultural water demand,and the comprehensive water supply is represented by the fixed alternative proportion production function.Then suppose the different situation of urban water supply and demand,and analyze the suitable de velopment mode.The results show that:? For industrial water supply,the regulation can be realized by adjusting industry investment and labor input.The regulation range of investment should be controlled within 0.6I10?1.1I10,and the regulation range of labor input should be controlled within 0.5P10?1.2P10.?For domestic water system,if it is current type or saving water mode,it can reduce the investment and labor input to reduce the water supply.If the urban residents have enjoyment type water consumption mode,it can increase the investment and labor input to achieve supply and demand balance.? For the comprehensive water supply and demand,the sustainable development plan is most suitable for the future development of the city.In 2030,Suzhou can appropriately reduce the water consumption per 10000 yuan of industrial added value to 12m3,the average water consumption per mu for agricultural irrigation to 225m3,maintain the growth rate of industrial added value and the growth rate of tertiary output value at about 3%,set the urbanization rate to reach 85%in 2030,investment and labor input are set as 38×108 yuan and 600 people to achieve the balance of water supply and demand for sustainable development.In addition,the simulation results also show that the accelerated depreciation method has a high matching degree with the supply and demand water industry,which can provide a reference for the selection of depreciation methods for the supply and demand water industry in the future.The model of urban industrial,residential and comprehensive water use constructed in this paper is general,and can also be applied to other cities' water supply and demand management.