Study On Several Core Problems In Ecological City Construction

Ecological city is the product of times in transition from industrial civilization to ecological civilization, a new form of spatial organization for human social activities and a human settlement corresponds with the era of ecological civilization where human and the nature are in harmonious coexistence in a certain space. Ecological city is a municipal administrative unit where social economy and ecological environment achieve harmonious win-win development. Development of all aspects within the administrative region of ecological city meets the requirements of sustainable coordinated development. The proposal on the concept of ecological city marks ecological awareness in the process of the urbanization. Ecological city is the advanced form of future urban development, the inevitable result of sustained survival and development of humanity and the inevitable direction of city development.Urban ecological carrying capacity, urban economic-ecological-social coordination degree, urban ecological security and urban ecological function zoning are the basis and premise of ecological city construction planning. We can only conduct diagnosis of a city, know the city well and thus develop scientific, reasonable and feasible plan for ecological city construction for guiding ecological city construction only after we thoroughly understand ecological carrying capacity, urban economic-ecological-social coordination degree, urban ecological security level and urban ecological function zoning of a city. Based on ecological cities home and abroad and relevant research, the paper studied on core problems in ecological city construction, such as urban ecological carrying capacity, urban economic-ecological-social coordination degree, urban ecological security and urban ecological function zoning of Pingliang City of Gansu province located in China’s Loess Plateau. Summary of the main contents is as follows:(1) Analysis of ecological carrying capacity of Pingliang City. The comprehensive urban ecological index system comprising of economy-resources-environment-society was established and the method of principal component analysis was adopted for analyzing the ecological carrying capacity of Pingliang City, and the results showed that:Ecological carrying capacity of Pingliang City gradually increased from year 2002 to 2011, changing from the state of not bearable to bearable state. In each bearing subsystem, economic carrying capacity and resources carrying capacity have relatively large impact on the overall ecological carrying capacity and their weighting coefficients were respectively 0.288 and 0.276, indicating that the contradiction among economic development, resource conditions and ecological environment has a direct impact on urban ecological carrying capacity. It also fully showed that in the past few years of economic development, there was a serious shortage of resources and the issue of recycling of resources was neglected. Meanwhile, environmental pollution was serious, resulting in a big ecological pressure. The state of ecological carrying capacity is not bearable.(2) Analysis of economic-ecological-social coordination degree of Pingliang City. The urban coordination degree evaluation index system covering economic development, ecological environment protection and social progress was established and the economic-ecological-social coordination degree of Pingliang City was evaluated and analyzed by using entropy evaluation method and coordination degree model.①During the period from 2002 to 2011, the overall coordination degree of ecological city construction in Pingliang City presented a rising tendency, growing from 0.2420 of year 2002 to 0.7588 of year 2011, at an annual average growth rate of 0.05168. This indicated that the level of ecological construction was constantly improved following the progressive development model of "uncoordinated-incongruously-basic coordination".②In detail, in terms of all subsystems, in 10 years, ecological environment protection and coordination degree of social progress subsystems presented a gradually rising tendency, ecological and environmental quality were gradually improved, public satisfaction to the environment and degree of social harmony improved constantly; The coordination degree among economic subsystems reduced gradually. It is necessary to work hard on reducing energy and water consumption.③In year 2011, the economic-ecological-social coordination degree index ranking of all counties of Pingliang City from high to low:Huating County, Chongxin County, Kongdong District, Jingchuan County, Zhuanglang County, Jingning County, and Lingtai County.④For clustering, seven counties of Pingliang City are classified into four types, Huating County and Chongxin County as highly coordinated; Kongdong District as well coordinated; Jingchuan County, Zhuanglang County and Jingning County as moderate coordinated; and Lingtai County as generally coordinated.(3) Analysis of urban ecological security of Pingliang City. The urban ecological security evaluation and analysis indicator system based on the pressure-state-response model was established. From the perspective of component interaction dynamics in complex systems, build urban ecological security evaluation model based on the maximum entropy (MIEP). The model is used for evaluating the urban ecological security state of Pingliang City from 2002 to 2011 and five-level evaluation grading standard is established. The results show that urban ecological security state of Pingliang City presented an increasing improvement state and the ecological security level of Pingliang City improved steadily. The urban ecological security state of Pingliang City was in a criticality safety status from 2002 to 2009, a relatively safe state in 2010 and 2011 and the value λ was the highest in 2011, reaching up to 1.3726. However, there is still a gap compared with ideal security level.(4) Combined with the function orientation of Pingliang City established by the state and Gansu Province, comprehensively consider the spatial economic and social development of Pingliang City and the integrity of administrative division; on the basis of Loess Plateau agricultural ecological area, divide Pingliang City into the western Hulu River Basin loess hills agricultural ecological sub-region, the central Liupan Mountain water conservation and mineral development ecological sub-region, the eastern Jinghe River upper middle reaches Loess Plateau agricultural and urban ecological sub-region three ecological sub-regions and 18 ecological function areas and establish ecological protection and economic development direction for each ecological sub-region. All these provided reference for ecological city construction and development.