Research On The Determination Of Urban Development Boundary Under The Dual Restriction Of Ecology And Scale

The study of the development boundary has a long history for 50 years in abroad.The study has been 10 years since 2006 in our country for the development of the boundaries.But there is still no uniform on how to determine the boundary.In 2014 the Ministry of Homeland joint Ministry of housing,National Development and Reform Commission and other departments to start the development of the boundaries of the delimitation.In the next five years,more than 600 small and medium-sized cities to determine the development of the boundary.In this situation,we urgently need a set of complete and easy to operate the boundaries of the development of the method,providing a reference to complete the development of small and medium-sized city boundaries.From the current practice point of view,urban development boundary demarcation work almost all in large and medium cities to complete,small and medium cities practice is relatively less,especially in plain area.Plain areas relative to the mountains,plateaus and basins,the terrain is relatively simple,the general height difference and slope will not be too much.This paper takes the Central District of Xiaogan City as an example to carry out the delimitation study of the development boundary in order to provide a way for delimiting the development of the boundary in the small and medium-sized cities in the plain area.Urban development boundary as an effective method of government control of urban growth,limiting the city's endless expansion,change the way of thinking,forcing the city transformation.Urban development boundaries can be divided into two types: rigid boundary and flexibility boundary.Rigid boundary is the safety of urban development bottom line,meeting the city's largest sustainable development largest scope line.Flexibility boundaries limit the extent of urban land expansion within a certain period of time,can be dynamically adjusted.This paper summarizes the domestic and foreign theories and practices,and puts forward the determination of the boundary of urban development from the perspective of ecology and scale.Abandon the single element to determine the boundaries of urban development,the ecological and scale into the same position,not only to maintain the ecological balance,but also to meet the needs of urban development land.Based on the theory of astronomical growth and landscape ecology,this paper analyzes the urban spatial expansion and the evaluation of urban land ecology,and puts forward scientific basis for the delimitation of urban development boundary.Refer to some success stories,we establish the ecological sensitivity evaluation system for the land of Xiaogan Central District Evaluation,classification evaluation level,which is extremely high,highly sensitive areas as the basis for determining the rigid boundary of the city.The forecast of flexibility boundary is based on the demand of urban construction land,and the forecast of scale becomes the key step.The article combs the current forecasting method of the future demand of urban construction land,and selects the simple and accurate gray system Prediction method,the GM(1,1)model was established to complete the land scale forecast of 2030 in Xiaogan Central District.On the basis of grading evaluation of land suitability,the flexibility boundary is determined by considering the trend of urban spatial evolution and the direction of urban land expansion.