Studyon Urban External Morphology Evolution And Spatial Expansion Prediction

The urban spatial form has a direct impact on the optimization and layout of urban structure.Sichuan is in the rapid development of urbanization,and Guanghan is in the rapid economic and social development in recent years,urban scale expansion rapidly.Based on the analysis of history spatial morphology evolution characteristic,through the analysis of the evolution of the city by the number of strength characteristics and evolution of the spatial form of city characteristics,city spatial evolution of the internal driving force analysis,to achieve the following objectives:(1)Comprehensive analyzed the evolution characteristics of expansion quantity,morphological evolution,extension direction,urban center of gravity moving distance,determining the evolution of the morphology of the expanding period and period of backfill designated standard,and obtain the 1990-2015 of each Guanghan city space form period.(2)In the view of Guanghan spatial form of the internal driving force,designated the expansion-backfill period for further confirmation,forecasting the period,number and direction of spatial extension in Guanghan City.In research methods,using the expansion intensity index to reflect the number of city expansion intensity evolution,using the compactness and fractal dimension to reflect the morphological evolution and using sector analysis and focus shifted to reflect the expansion and evolution,the comprehensive evolution characteristics designated the "expansion backfill" period of Guanghan?s form,and constructed the city space form internal drive index to divide the expansion-backfill period,predict the future development period,number and direction of Guanghan City.The results show that:(1)The inflection point of spatial evolution quantity strength characteristics in 1999-2016 appeared in 1999 and 2009,the change trend of 1990-1999 in Guanghan city was high speed,rapid expansion of built-up area of the city,city spatial intensity evolution trend of rising;1999-2009,slowing down the pace of expansion of Guanghan city,strength index of space expansion showed a steady decline trend,the overall level of city spatial intensity was low;Extension strength of the spatial shape evolution of Guanghan city was high and city area expansion rapidly in 2010-2016.At the same time,city spatial intensity fluctuations rose significantly.(2)1990-1999,Guanghan city had a high compactness,low fractal dimension,gravity transfer largely,urban form changed greatly,city expansion direction concentrated in the northern area of Guanghan City,the spatial form of Guanghan was discrete,urban form was in the expansion period;1999-2009,Guanghan city had a low compactness,high fractal dimension,gravity transfer less,urban form changed little,the propagation direction of city in the south of the area,the spatial form of Guanghan was completed,Guanghan city form developed in backfill period;2010-2016,Guanghan city had a low compactness,low fractal dimension,gravity transfer largely,urban form changed greatly,the direction of city expansion concentrated in the northern area of Guanghan City,the spatial form of Guanghan was discrete,urban form was in the expansion period.(3)In Guanghan,the main driving force of evolution is the increased non-agricultural population units construction land,the rate of annual growth amount,city non-agricultural population growth,GDP annual growth rate of construction land,construction land fixed assets investment factor,and the drive in urban morphology in the expansion period is higher than over the linear driving force return level,backfill period driving force below historical levels of linear regression.(4)In the future,the expansion of Guanghan urban spatial form belongs to the expansion period and its expansion area is 2626.6153hm2.The direction of expansion is mainly in the northeast and southwest.The final forecast to 2020 Guanghan urban spatial form will be in the expansion period,new added urban area is 2626.6153hm2.The area of new added area is the largest in the northeast,the second in the southwest,the least in the northwest and Southeast.Finally,this paper provides some suggestions for the future development of Guanghan city.