The Sprawl Research On Valley City Based On Cellular Automata

With the rapid development of economy and social, the urban population is increasing more and more as well as a necessary urban expansion. This thesis takes Lanzhou as the study area, applies SLEUTH model to rebuild the expansion process based on remote sensing and GIS, and then predicts the urban expansion in the future. Considering the expansion characteristic of valley city, the thesis finds out the driving forces of urban expansion in Lanzhou and makes suggestions on urban development. The content of thesis is as following:Firstly, the thesis introduces the research background, research progress and trend and urban expansion model, then refers to main study area, method, technique and what's Cellular Automata.SLEUTH model includes four growth rules: spontaneous growth, new spreading center growth, edge (organic) growth, road-influencing growth. There are five growth coefficient of model: diffusion coefficient, breed coefficient, spread coefficient, slope coefficient, road-gravity coefficient. Input data of the model and calibration method is the focus in this thesis.Taking remote sensing image as the main data sources and combining with urban planning maps, topographic maps and other maps, with the support of GIS technology, the author gains maps about urban area and roads in different periods, and also gains maps about slope and shadow of Lanzhou city from the DEM. Then combining with socio-economic statistical data, the author builds the spatial and attribute database of the study area.Based on SLEUTH model, the author simulates and predicts the urban expansion, and explains the rebuilding and predicting results under the consideration of statistics. Considering the possible driving forces, analysis about Lanzhou city expansion is got.It is proved that SLEUTH Model algorithm is simple and intuitive which can be suitable for the dynamic simulation of urban expansion. The results indicate that the left land for urban expansion is quite limited; urban expansion is mostly influenced by road and traffic; slope is a major limitation for urban expansion. Lanzhou city expansion has different driving forces in different time, including natural environment, historical reasons, population growth, economic development, traffic conditions, policy factors and so on. This study will contribute to the development of the spatio-temporal simulation of geosystem, especially for the theory and methods, to promote the theoretical study of the evolution of urban expansion, to promote the application of Cellular Automata in urban expansion, and to advance a further study on the dynamic evolution model of urban space. At last, the author hopes what he did can be significant for urban planning and the sustainable development of Lanzhou city.