Study On The Delimitation Of Urban Development Boundaries Under The Constraints Of Urban Expansion Simulation And Ecological Spatial Quality

It has been 40 years since reform and opening up.China has been in the rapid development stage of urbanization,which not only represents the urbanization of the population,but also shows the disorderly expansion of urban land under the effects of natural,economic,transportation and policy factors,and it will still present the trend of expansion in the future.The lack of reasonable control will inevitably lead to the disorderly spread of the city,and bring a series of trouble such as environmental degradation,waste of land resources,the weakening and degradation of the ecosystem services,and other problems of ecological and resource management.However,due to the serious imbalance between the urbanization and the development of land urbanization,the existing land control policy has failed to protect the basic farmland,the ecological sensitive area,the water source area and also failed to effectively guide the rational expansion of the city.In this regard,the Chinese government has proposed that the overall planning of the city should be gradually shifted from"expansionary planning" to "overall planning",to delimit the boundary of urban development,to limit the scope of urban expansion,to promote the intensive and economical use of land,and to optimize the spatial distribution.At present,the method of delimiting the boundary of the urban development is mainly based on the city expansion simulation,in order to build the suitability or evaluate the potential of regional expansion,and to outline the urban development boundary,only considering the non ecological factors such as economy and policy,which is slightly inadequate for the quality of ecological space.In the long run,urban land will occupy important ecological resources and bring about the incompatibility between urban development and ecological protection.Therefore,this paper,taking Changwu area with high urbanization level and ecological resource protection demand,has built a comprehensive evaluation method of regional ecological space quality with the principle of "ecological priority".On the basis of high precision urban land use expansion simulation,combined with scale constraints and ecological constraints and a boundary delineation model for urban development is designed and implemented under the constraint of urban expansion simulation and ecological spatial quality.The main research contents and conclusions of the paper are as follows:(1)Spatial expansion and driving force analysis of urban land useThrough three aspects of scale change,layout change and morphological change,the spatial growth and change of urban land use in the study area is analyzed and evaluated,and the spatial temporal evolution characteristics and regional differences of urban land expansion in the study area for 1995-2015 years are reflected.The results show that the speed of expansion of the research area has experienced a process of high and low,mainly in the early stage of research,mainly with high speed expansion,and the latter is mainly medium and low speed expansion.In the whole research period,the growth of edge,filling type,satellite city growth and urban land use tend to be centralized.Through the construction of grey correlation analysis,and selecting 10 driving factors of three categories,nature,location and social economy,the driving force mechanism of urban land expansion in each period is explored.The results show that the dominant driving force varies with time,but during the whole study,the development intensity,distance from the roads and the GDP have always been an important factor to promote the urbanization process of Changzhou.(2)Evaluation of ecological space qualityFrom the aspects of "ecological quality" and "environmental sensitivity of ecological land",a method for evaluating the quality of ecological space and environment was constructed.The InVEST geographical evaluation method was used to evaluate the habitat quality of the research area for 1995-2015 years,and the results of the ecological sensitivity evaluation of the study area were obtained by the index construction,and the ecological space quality of the study area was evaluated.From the result of the evaluation,the river waters,the ecological forest and the wetland park have maintained high ecological space quality and should be protected,and in the central urban area,the ecological space quality has gradually declined because of the interference of more and more human development activities which is also an important potential area for the expansion of the city in the future.(3)Simulation of urban land expansionBy constructing the SLEUTH model,the urban land in the study area is simulated and forecasted in 2030,and the scale of urban land use in the target year is obtained through the grey prediction model.Combined with the evaluation results of ecological spatial quality,the simulation results are revised under the dual constraints of scale and ecology.Assuming that the expansion probability exceeds 50%as a 2030 expansion plan,the target year is expected to expand by 295.50km2,of which the expansion probability is 91-100%,accounting for 54.07%,which is mainly distributed around the existing urban land in methods of internal filling and edge growth.(4)Delineation of urban development boundariesAccording to the simulation results of urban land use expansion predicted by the SLEUTH model in 2030,the urban extended boundary was extracted.Combined with the results of ecological space quality evaluation,the urban land expansion simulation results of Changzhou urban area in 2030 were corrected.According to the revised results,the urban expansion boundary was corrected,and the area statistics and edge detection were used to extract the urban development boundary of Changzhou City in 2030,the land area covered by the urban development boundary was designated as 593.65km2,and the space spread outward from the center of Changzhou City as a center,mainly in the northwestern and southeastern regions of the New North District and in the northern area of Wujin District.Urban development boundary delineation model based on the concept of "ecological priority"avoids the reverse control of random events such as policies and investment introduction.It is more in line with the concept kernel of urban development boundary than the traditional boundary demarcation method,and has obvious advantages in the protection of ecological resources.