Study On Urban Spatial Evolution And Optimization In The Area Around Dianchi Lake

Urban space is the place where urban population depends on survival and development.At present,with the accelerating process of urbanization,the interaction between human activities and natural environment factors has a more profound impact on the evolution and development of cities.The urban spatial evolution of Plateau Lake area is different from that of plain and mountainous lake area.The formation process and evolution mechanism of Plateau Lake area have their own particularity,and the optimal control strategies are also different.Based on this,this paper chooses the area around Dianchi Lake,a typical area with the superimposition of multiple characteristics,such as "ecologically fragile plateau lake area,active urban economic development area,multi-cultural integration area,lake ecological environment and urban development are not in harmony",and the paper also discusses the pattern,mechanism and optimization of urban spatial evolution in the area around Dianchi Lake.The study enriches the theory of urban geography,serves the development needs of local cities,and provides empirical reference for ecologically fragile plateau lakeside cities to achieve green development.Based on human geography,historical geography,econometrics,urban and rural planning,management science and other disciplines,This paper as an applied research mainly uses system theory,human-land relationship theory,sustainable development theory,synergy theory and urban-rural development theory,uses ENVI5.2 remote sensing image processing,ArcGIS 10.2 spatial number,analyzes the environmental foundation for urban development,the process and characteristics of urban spatial evolution,restores the basic pattern of urban space in different periods,analyzes the internal mechanism of urban spatial evolution in the area around Dianchi Lake,and evaluates the urbanization and ecological environment in the area around Dianchi Lake.On the basis of coupling and coordinated development,this paper analyzes the existing problems in urban planning,industrial layout,structure and function of the area around Dianchi Lake,and finally puts forward a series of urban space optimization control strategies.The main results and conclusions of the study are as follows:(1)The spatial expansion of urban land is obvious.During the 27 years(1990-2017),the urban land has expanded 5.29 times,with an average annualexpansion rate of 15.24 km.At the same time,within the circle of 2-4 km and 4-6 km away from the coast of Dianchi Lake,the urban land expansion intensity is the highest,which is the main expansion area.(2)The evolution process and characteristics of urban scale structure in Dianchi Lake area are characterized by the transfer from the South Bank of Dianchi Lake to the North Bank of Dianchi Lake,the change from single center to multi-center,and the obvious distribution of traffic arteries around the lake along the river.Before the founding of New China,from 1949 to 1990,from 1991 to 2002 and from 2003 to now,the urban space around Dianchi Lake has undergone obvious structural changes and characteristics changes in different types of space,such as commerce,industry,residential life,public services,transportation and ecological green space.The evolution process of urban spatial morphology around Dianchi Lake in different periods is as follows: single center structure around Cuihu Lake(before 1949),single center concentric circle layer structure around Cuihu Lake(1949-2002),and multi-center concentric circle layer structure around Dianchi Lake(since 2003).(3)Linear regression analysis showed that: the proportion of the added value of secondary and tertiary industries to GDP,the green coverage rate of built-up areas,the proportion of employed persons in secondary and tertiary industries,the proportion of non-agricultural population,the total retail sales of consumer goods per capita,and the discharge of industrial wastewater per capita have significant impacts on the urban air space around Dianchi Lake.(4)The coupling and coordinated development of urbanization and ecological environment from 1990 to 2015 is manifested as follows: during the 26 years,the overall level and quality of urbanization have been improved,the level of population urbanization has been raised rapidly,the level of spatial urbanization has been raised slowly,the level of economic urbanization has been rising rapidly,and the level of social cities has been rising rapidly.The level of urbanization fluctuates sharply and rises slowly;the pressure of urban ecological environment fluctuates as a whole;the supporting capacity of urban resources fluctuates and is unstable;and the urban ecological security capacity is becoming stronger and stronger.But in recent years,the urban environmental threat is increasing rapidly,and the urban environmental response index fluctuates greatly;urbanization and ecological environment The co operation of environmental coupling has experienced three stages: "basic incompatibility-basic coordination-advanced coordination".(5)At present,there are some problems in the urban space around Dianchi Lake,such as imperfect urban planning,unreasonable industrial spatial layout,contradiction between urban spatial scale and urban development speed,optimization and adjustment of urban spatial function and structure.(6)In the future,urban space optimization in the area around Dianchi Lake should be combined with the top-level design strategy of urban space,focusing on the optimization of urban ecological green space structure and ecological management,the optimization of urban public service space layout,the construction of urban "fast-slow three-dimensional" traffic network system,and the further optimizing urban economic space,so as to improve the quality of urban space development.