Quantitative evaluation and analysis on the coordinated development of the urbanization and ecological environment in Xining city

: Taking Xining City as the research area, the index system of coordinated development of urbanization and ecological environment in Xining City is constructed by combining qualitative and quantitative methods. The index and comprehensive index scores are obtained by using analytic hierarchy process and weighted summation method, and the coordination degree between urbanization and ecological environment in Xining City whose evolution trend is evaluated and analyzed is quantified by combining the coordination degree model. The results show that the urbanization level of Xining has been on the rise in the past 10 years from 2008 to 2017, and after the urbanization level of Xining has been improved, the eco-environmental quality index, although which has a characteristics of fluctuation, has been also on the rise as a whole. From the analysis of coordination degree, the coordination degree showed a downward trend year by year from 2008 to 2012, in which the coordination value in 2010, 2011 and 2012 were below 0.4, showing a moderate imbalance state; from 2013 to 2017, the coordination degree showed a rising trend year by year, and showed a relatively stable state.


Introduction
Urbanization is also called City and town-rization in China. It means that with the development of social productivity, the progress of science and technology and the adjustment of industrial structure in a country or region, its society has changed from a traditional rural society dominated by agriculture to a modern city dominated by non-agricultural industries such as industry (secondary industry) and service industry (tertiary industry). The historical process of the gradual transformation of the type society. [1]. But while urbanization promotes economic development, it also makes the ecological environment pay an irreversible price. In recent years, the urbanization construction of Xining City is fast. The built area of Xining City has expanded from 57.17 km2 in 2002 to 90.00 km2 in 2017. It is estimated that by 2030, the planned area of Xining City will reach 196.84 km2 [2,3]. The annual increase of urban population indicates that Xining City has gradually entered the stage of rapid urbanization. However, there will be an inevitably conflict between the development of rapid urbanization and the ecological environment such as water, atmosphere, land and biology. The increasingly scarce resources and increasingly highlighted environmental problems have become the constraints of urban development. Therefore, how to coordinate the construction and development of urbanization and ecological environment has become the urgent task of the sustainable urban economic and social environment. development [4].
Through the construction of coordinated development model, we analysis the coordination status of Xining's urbanization and ecological environment compound system, and provide the main theoretical basis for promoting Xining to build a national innovative pilot city and promote sustainable development. Through quantitative analysis of the urbanization and ecological environment construction in Xining from 2008 to 2017, the relationship between urbanization and ecological environment is clearly understood, so as to provide suggestions for the harmonious development of urbanization and ecological environment in Xining, promote the sustainable development of Xining, and promote the construction of Xining as a national innovative pilot city.

Data Sources and Standardization Processing
Environmental Protection. " Environmental protection planning, in order to eliminate the influence caused by the difference of magnitude and dimension of data, requires standardized data processing [5], the formula is: In the formula: I is the year; J is the index serial number; x is the index data. In order to unify the change direction of indexes, some indexes need to be processed by changing direction. The formula of changing direction processing is zij=1-Zij. After processing, the value range of data is between [0-1].

Establishment of Evaluation Index System
Based on the conceptual model of PSR, which was put forward by the Organization for Economic Cooperation and Development (OECD) and the United Nations Environment Programme (UNEP) at the end of 1980s, this paper establishes an index system reflecting the comprehensive development level of the ecological environment from three levels, namely, the pressure of the ecological environment, the state of the ecological environment and the response of the ecological environment. After standardization, the hierarchical analysis method and Delphi method (also known as expert consultation method) are used for hierarchical assignment to determine the weights of each level and index (Table 1)

Urbanization and Comprehensive Development Level of Ecological Environment
The comprehensive development index of urbanization and ecological environment in Xining City from 2008 to 2017 is obtained by weighted summation of layers. The formula is [6]: In the formula, y is the index of urbanization or comprehensive development of ecological environment; yi is the index of the Ith index; Zi is the index of the Ith index processed by the above standardized data; ti is the weight of the Ith index.

Quantitative model of coordination degree between urbanization and ecological environment in Xining
Coordination is a kind of benign interrelation between two or more systems or system elements. It is a relationship of proper coordination, perfect harmony, and benign circle between systems or elements within systems. Coordination degree is a quantitative index to measure the degree of coordination between systems or elements [7]. We uses the following coordination degree model to quantify the coordination degree between urbanization and ecological environment in Xining. The model is as follows [8]: In the formula: C is the degree of coordination between urbanization and ecological environment, C <(0,1), U1 and U2 represent the urbanization subsystem and the ecological environment subsystem respectively.
In order to more clearly reflect the coordinated development degree of urbanization and ecological environment in Xining, the coordination degree between the two systems is graded [9], as shown in Table 2.

3.1Test results of comprehensive level of urbanization and ecological environment in Xining
By using formula (2), the comprehensive index values of urbanization system and ecological environment system of Xining City from 2008 to 2017 are calculated (Table  3), and the comprehensive index changes of urbanization and ecological environment of Xining City in recent 10 years ( Figure 1) are drawn.   Figure 1 shows that the ecological environment of Xining City has been in good condition in the past 10 years, and since 2011, the comprehensive ecological development index of Xining City has shown a dramatic growth trend. In 2016, the ecological environment development index has reached more than 0.4, which is in line with the approval of Xining City as a national innovative pilot city. This is inseparable from the green development, paying more attention to the construction of ecological environment, strengthening the protection of ecological environment, with the high-speed economic development. Coordination index

Particular year
Coordination index