Study on Urban Development and Climate Change of Lanzhou City from 1978 to 2000

Regional development and environmental change has been one of the most frequently discussed issues among various intergovernmental conferences since cities have proved to be the biggest carbon source of the world Greenhouse Gases. Based on meteorological observation data and socio-economic statistical data from 1978 to 2000, this paper gained the spatial-temporal distribution features of urban climate change and urban development level of Lanzhou City, one of the most typical valley-basin cities in the northwest of China. The main conclusions are as follows: From 1978 to 2000 in Lanzhou City, the Urban Heat Island Effect of winter was more prominent than that of all the other three seasons. The Urban Dry Island Effect of spring stood out most obviously and could be regarded as the fast drought signal of fast urban form sprawl and rapid urban economy expansion. The difference of wind speeds between Lanzhou City and Yuzhong County had a peak in 1982 and a valley in 1994 which divided the whole period into three sub-periods. Fast population growth coupling with fast urbanization would lead to fast heat emission with the help of the unique valley-basin urban form. Fast urbanization made a great deal of natural lands turn to urban concrete lands so as to restrain the water exchange between land soil and above atmosphere, which resulted in the decrease of Relative Humidity and the enhancement of UDIE. In addition, the bad correlation between population and wind speed was mainly due to the block of high-rise buildings in urban areas when it was passing through the city, which was the common fact of most cities in China. The whole study was greatly dependent on statistic analysis and urban-rural comparison, both of which helped to make the final results logical and credible. At last, the perspectives of this study were also discussed.