Study On Dynamic Characteristics Of LUCC And Urban Expansion In Cheng Du City Based On GIS And RS

In recent years, the city and its suburbs have the rapidest change speed of the earth’s surface.Great changes have taken place in urban land use types and the structure of land using. As the engine cityof western development，with great location advantages, LUCC Chengdu city has changed a lot sincethe1980s with the fast development of the social economy. Urban land expands significantly, triggering aseries of problems, such as traffic congestion, environmental degradation, etc. The objectives in this paperanalyzed the LUCC and expansion in Chengdu from1978to2010based on Landsat MSS/TM/ETM+imagery, following the remote sensing and GIS technology, fund the driving forces of the expansion,revealed urban expansion tendency, and provided a scientific basis for decision-making departments inChengdu city. The main conclusions are as follows:（1）Dramatic changes have taken place in LUCC of Chengdu in nearly30yearsIn past nearly30years, land use in Chengdu changed dramatically. The general characteristic is thatthe non-agricultural land continuous increased and agricultural land reduced. The largest increase ofnon-agricultural land is urban built-up land with increased1956.0716km2in32years from98.1421km2in1978to2054.2137km2in2010, the average annual increased area was61.1272km2. Maximum reduction ofagricultural land area is woodland with the decreased2812.3828km2in32years from4989.8884km2to2177.5056km2in1978to2010, and the average annual reduced area was87.8870km2. The cultivated landarea in Chengdu shows a trend that increasing in first period then decreasing during the1978-2010, withthe average annual growth of55.6241km2from1978to2002and the annual average decrease53.8212km2year in2002-2010.There are significant differences between the conversions of land use types at different times inChengdu. Both the he conversions of land use types between the woodland, grassland and cultivated land in1978-2002and from the cultivated land, forest and urban land to construction land in2002-2010has a bigdifference. The composite index of LUCC increased56.3in1978-2010, and reflected a very intense changeof LUCC in Chengdu.(2) Urban expansion showed significant spatial and temporal change patterns in the recent30yearsThe analysis results based on spatial analysis technique of GIS and application of the model of urbansprawl showed that urban expansion was in the process of significant spatial and temporal change patterns in same period. Average annual expansion rate both the period of1978-2002and2002-2010was10.71%and47.73%, respectively. The main expansion direction in Chengdu is northwest, west and southwest area，but the fastest expansion is north, northeast and east area. Urban expansion showed the extended mode of“compact circle style", the main directions of the city center expansion was the northwest, west andsouthwest area.(3) The main driving forces of urban expansion is economic development and urbanizationFactor analysis showed that economic development and urbanization are the main driving forcesleading to the expansion of Chengdu city. There was an upward trend in Chengdu’s GDP, industrial output,the output value of the three major industries, the actual use of foreign capital and fixed asset investmentin1999-2010; Chengdu city has made remarkable achievements with the fast economic development.Meanwhile, non-agricultural population, traffic areas, the per capita living space of urban residents andurban green space area also showed an upward trend; and this greatly improve the level of urbanization.Further more political system and the natural environmental factors also contribute to urban expansion inChengdu.(4) The relevant suggestions was proposed based on Chengdu LUCC and urban expansion analysis,such as recommendations to strengthen the protection of land resources, the development of urbanmultidimensional space, energy conservation, protection of special land. This will help to improve theLUCC efficiency and quality of city, provide reference information for the city overall planning forsustainable city development.