The Prediction Of Urban Growth Boundary Using GANN And CA

China is in the rapid development period of urbanization, the pace of construction of the city is accelerating, and more and more people are pouring into the cities and towns, which not only bring the rapid economic development, but also bring the disorder spread of the city, urban spatial structure chaos and other issues. Urban spatial growth is in urgent need of changing from quantity to quality. The urban growth boundary is an effective means to solve the urban sprawl, and it can guide the rational expansion of the city and the protection of the ecological sensitive area. Beijing, as the capital of China, has a common problem of metropolitan areas; urban sprawl is in disorder, it is urgent to delineate the urban growth boundary to guide the rational expansion of the city.Based on the theory of urban growth boundary, this paper deeply understands the genetic algorithm, BP neural network and cellular automaton method, and analysis the influence factors of urban growth boundary in Beijing, and select the suitable for the Gann- CA model 18 influencing factor, establish the urban growth boundary model, carries on the simulation model with the 2005 and 2015 the status data, and the construction land suitability evaluation, Beijing in 2025, urban growth boundary are predicted, and finally Beijing urban growth boundary by boundary rigidity and elastic boundary together. The main conclusions are as follows:(1)Through the analysis, we selected 18 factors which are suitable for the urban growth boundary model, respectively: Elevation, slope, slope direction and distance to the road, the distance to the railway, to the administrative center of the distance, the distance to the green, distance to the building, area students GDP, population, adjacent to all kinds of unit number, land use types and policy planning layout.(2)Model number test results are: Area matching value is 96%. The test results for the number of spatial positions are as follows: the numerical value of kappa system is 0.812.Overall model accuracy is higher. According to this model, the elastic boundary area is 1738.98 square kilometers in 2025. The District is relatively small in the northwest direction. Also there is the largest expansion to Fangshan District in southwest direction. And Beijing expands more to Tongzhou District and Chaoyang District in the southeast of district. In general, the largest increase area is in Tongzhou District, which is 43.22 square kilometers.(3)At the time of construction land suitability evaluation, selected slope, elevation, park water, land using types, urban land and nature reserve as an evaluation factor and level analysis method to determine the weight, the final delimitation of Beijing rigid boundary area of 3297 square kilometers.(4)Through the study of Beijing urban growth boundary demarcation, the demarcation methods and recommendations can provide certain reference function for other cities in the delineation of urban growth boundary, and can provide guidance for the formulation of urban planning and urban development policies.