The Urban Expansion Simulation Of Mountainous City Based On Ecological Security

China is a typical mountainous country, and mountain area occupy about two-thirds of all the land area. Hilly and mountainous cities are widely distributed and the ecosystems are diversified. Nowadays, as the promotive power of the urbanization and industrialization, the Hilly and mountainous cities rapid expand and formed various city development models. Such as polycentric and group model (FAR), apart model of the new and old urban, green core or ring model etc. are forming because of the different geographical conditions. On the other hand, the mountain environment are most related with rapid urban construction, the traffic construction destroy the natural landscape pattern, the urban sprawl make the Impervious surface replace urban green area as well as intricate ecological problems. Based on the analysis of the natural conditions and the FAR, we chose ten indices to assess the degree of ecological security, taking a case of metro Chongqing. We got two majnt. The built environment factor were most related with FAR, road density and population density as well as Air Quality Index. The natural environment factor were related with vegetation ratio and soil loss. We classified the study areas into five ecological zones:extremely fragile area, more fragile area, less fragile area, less suitable area and more suitable area. Among which, extremely fragile area most distributed in several commercial areas in urban core area, and more fragile area located in the areas around urban core and along two big rivers and four mountains.The intense development of Chongqing leads to various ecological effects, such as landscape fragmentation, urban heat island intensification and pollution release. By the assessment of Ecological Security, we analysed the land use types and got the connection between the ecological security and land use types. With the help of the shortest-distance model, ARCGIS and the hydrology model, we construct the frame of land pattern and the the ecological security area. Based on the assessment of Ecological Security and classification of ecological zones, we refine the ecological restricts to define the different exclusions in SLEUTH. And then, five scenarios were generated:Maintain Status Quo (MSQ), Moderate Farmland Protection (MFP), Ecological Forest Protection (EFP), Ecological Wetland Protection (EWP) and Slope-limit Development (SD). By evaluating the simulated results from urban expanding and ecological importance, we get the conclusion:(1) The present urban expansion spread around seriously, and the each groups come into being the whole. (2) Each ecological scenarios managed to the respective targets, controlling the expanding of the building land, restricting decrease of the farmland, protecting ecological wetland and forest as well as reducing the development of the low area between mountains. (3) Although the ecological protection as the urban developing is forcefully emphasized in the present city planning, some ecological details needed to be pay paid attention. Such as the protection of the north of Tongluo mountain, the degenerate ecological wetland because of the development along the rivers and farmland protection etc. In a word, we should consider of the geographical conditions, landscape pattern, ecological protection and so on.