The Discussion Of Urbanization In China Based On DMSP/OLS Data

Urbanization is a revolutionary process until today, and a natural process driven by all kinds of opportunities provided by the city to a large extent and closely combined with economic development, social development and environmental protection. The city is the engine of economic growth and cultural development, which can provide numerous benefits for the residents, but the spontaneous development of the city will have a negative effect. There are large differences between China and other countries, the interior differences in the process of urbanization of our country make the characteristics of China’s urbanization unique. It is expected that China will increase nearly 290 million urban population from 2014 to 2050. To meet on such a scale population settled, China needs a certain scale of land capacity in the future. So, it’s necessary to understand the process of urbanization in our country to a certain degree. This paper discussed the urbanization process in eight regions of China and two sample cities during 1992-2012 based on the light data, the goal is to provide some references for China’s urbanization.Based on DMSP/OLS nighttime stable lights, we discussed the expansion trends and features of urban land areas in eight regions in three periods when threshold values were 8, 20, 41, which were determined by natural breaks classification method. The results show that the urban land area is inversely related to the threshold and has a high reliability when DN≥20. The urban land area reaches 326 thousand km2 and occupies about 3.4 percent of the total land area in 2012 when DN≥20. The proportion of urban land area is high in the coastal region, middle in the central region and low in the western region. The trend of annual average expansion intensity index of urban land area is similar to the proportion of urban land. The land urbanization is faster than population urbanization and the urban population density tends to be sparse. The population density is low in coastal region because of its flat terrain and high in some Midwest region where is limited by terrain and water resource. The population elasticity coefficient of urban land expansion has its own characteristic that the coefficient is high in the Northeast region owing to low urban population increase and low in coastal region because of the high population aggregation ability. The annual growth rate of secondary industry and the tertiary industry output value of eight regions in the phase I is lower than that in the phase II, indicating that China’s overall economic is slowing down. The economic expansion elasticity coefficients of middle reaches of the Yangtze River and the northeast region in the second stage are higher than the phase I and the difference is large, however, other regions are relatively stable. The density distribution of urban space directly display and can be roughly divided into high, medium and low dense area. The population economy urbanization correlation coefficient of 30 provinces(city) is decreased because of more factors affect the urban population.The trend and characteristic of urban land use in Lanzhou city and Jiuquan city in 1992 and 2012 were analyzed based on statistical data, TM image and light data. The conclusions are as follows. There are differences among the three kinds of data sources in two cities, the statistical area of Lanzhou city is larger than the extraction area from TM image and less than the area when DN≥20. The situation in Jiuquan City is relatively complicated. Lanzhou has small base area, so the proportion and the expansion intensity index are higher than that of Jiuquan City, but its annual growth rate is less than Jiuquan city. The growth rate of non-agricultural population and the population expansion elasticity coefficient in Jiuquan city are greater than these in Lanzhou city, maybe because of the agricultural population settled in small city has lower threshold, indicating the urban land expansion in Lanzhou city is more reasonable than Jiuquan city. The annual growth rate of second and tertiary industries in Jiuquan city is more than that in Lanzhou city, the economic expansion elasticity coefficient is reverse. The results show that despite the land area in Jiuquan city grow fast, the new land use efficiency is inferior than Lanzhou city. The gravity center of Lanzhou city were Xigu district and Chengguan district in the early stage. After 20 years, the four districts develop together, however, Honggu district is a neglected area. Jiuquan city core area is based on the old city, although a new growth pole was found, its development level was less than the level of the old city.In the process of promoting new urbanization, it is necessary to properly deal with the relationship between improving people’s living condition and the land conservation and build appropriately compact urban. Also, a series of integrated policies to improve the living standards of urban and rural residents is needed.