Construction Land Expansion Characteristics Analysis And Simulation In Mountain City

The global urbanization process entered the stage of accelerated development and land use/cover change has become the hot topics in the study of global environmental change since the 21 st century.The urbanization process in China has entered the stage of accelerating In recent years, land use/cover change has become the focus of global environmental change research. As the most violent and the most visually forms of land use change of land used for urban construction,its extension study also become an important aspect in the research of land use. Rapid urbanization has led to the development of urban construction land increasingly tight,Supply and demand of land for construction is particularly prominent, particularly for the mountainous city. Research shows that urban construction land is mainly composed of agricultural land, especially surrounding the cities of farmland conversion, which leads to cultivated land decreasing and environmental pollution etc. As a result, if not controlled and management, not only will have a negative impact on the development of social economy, and will have more serious consequences for the environment. How to maintain a healthy fast urbanization and promoting economic development and ecological environment of sustainable common development, achieve society and environment, the harmonious development of man and nature, the purpose, has become a topic of many scholars attention.Based on the terrain gradient change of urban construction land expansion.Using the 2001, 2007 and 2014 remote sensing image data of the main urban area in Chongqing.to extract the urban construction land by using the method of decomposition of mixed pixels.Computing the fractal dimension of construction land,compact index and the radial index to analyze the main urban construction land expansion form change characteristics of horizontal direction.Combined urban construction land with the regional elevation and relief, Analyse the construction land differentiation characteristics of terrain.Using CA- Markov model combined with construction land expansion limit constraint conditions and influence factors in the study area, Compare the situation simulation of construction land expansion in 2014 and the actual situation in 2014, Kappa coefficient of 0.81 that the model is valid.The results show that the city scale expanding rapidly, and the area of construction land was increased from 237.62 km2 to 818.85 km2 during the period of2001 to 2014. From the simulation results,the area of construction land was increased from 818.85km2 to 1442.25km2 during the period of 2014 to 2020.Comprehensive fractal dimension index, compact city index, the radial index in general, Urban expansion is compact extension type, but in 2007-2014 phase shift for epitaxial extension type.Urban expansion appears as compact extension type in 2001-2007, but it was turn to epitaxial extension type in 2007-2014.the southwest and southeast area epitaxy expand and other parts is given priority to with compact extension in2014-2020.the urban construction land in low elevation area was grown in saturated state,while high elevation area is a growing momentum,From the point of rolling degree analysis, construction land are unable to expand to larger area.