Study On Coupling Relationship Between Urbanization And Water Use In Xi'an City

Urbanization is a comprehensive change of social economic structure and population structure, which is accompanied by economic development.It generally performances as a high concentration of population, resources, information, production materials and other economic factors in a certain area. By the end of 2016 China's urbanization rate has reached 57.35%.The rapid growth of the city scale and amount has brought tremendous pressure on the water supply.Xi'an is located in the semi-arid and semi humid area with shortage of water resources.Water resources per capita is only 1/11 of Chinese average per capita water resources. The shortage of water resources has restricted the urbanization of Xi'an obviously.This paper analysed the relational characteristics between the process of urbanization and urban water use by discussing their relationships, finding out the interation between them and some quantitative results. The main contents and conclusions of this paper are as follows(1)The trend of household water consumption, agricultural water consumption, industrial water consumption and public water consumption in Xi'an city were analyzed by using Mann-Kendall method. Based on urbanized population, the process of urbanization is divided into three stages. The results shows that the agricultural water consumption was significantly reduced, and the industrial water consumption experienced a process of first increasing and then decreasing.Household water consumption and public water consumption both increase significantly.(2)Constructed a coupling coordination model, an evaluation index system was established to determine the coupling coordination level of urbanization system and water use system in Xi'an city.From the view of the level of coupling coordination, the urbanization system and water system of Xi'an city have gone through mild disorder, barely coordinated, primary coordination,intermediate coordination, good coordination, and ultimately achieve high quality coordination.It can be seen that the relationship between urbanization and urban water use in Xi'an city is benign and sustainable.(3)Taking water resources as a main constraint, this paper established a multi objective decision model of city's appropriate scale.Grey prediction model GM(1,1) and secondary exponential smoothing method are used to predict the relevant indexes in the model. The time path equation of urbanization level in Xi'an city is derived by using the two phase calculation method proposed by the United Nations. Finally, using the multi-objective genetic algorithm to solve the model under different water supply conditions. The results show that under the conditions of water diversion the appropriate population of Xi'an city in 2025 is 9.2 million,GDP is 1080 billion.By the year of 2030,the population is 9.47 million, GDP is 1258 billion.