Environmental effects of urban expansion in medium-sized cities of China: A case study in Mianyang city

Urban expansion continues to accelerate and herewith changes profoundly the Earth surface and results in many environmental consequences, such as affecting ecological sustainability in the rapid urbanized area of China. Therefore, it is of significance to map the intensity and spatial pattern of urban expansion and assess its environmental effects. The objectives of this paper are three-folds: (1) using two-period Landsat TM/ETM images from 1988 to 2000, urban expansion in Mianyang prefecture of China was mapped out. Results showed that urbanization in Mianyang increased dramatically with an expansion rate of 76.8%. Most of the new urban development was done at the cost of arable land. (2) The study found determinants of urban expansion, and concluded that urban expansion was constrained by biophysical as well as social-economic factors. The change of industrial structure in downtown area and the improvement of transportation were predominant drivers for urban expansion. (3) Combining with statistical environmental-data, the paper analyzed environmental effects of urban expansion in Mianyang, such as urban heat island effect (UHI), water pollution and acid rain.