1. Introduction
1.1 The Urbanization in China
It is believed by many experts that the urbanization process follows an "S" shape (Northam, 1975; Davis and Golden, 1954; Graves and Sexton, 1979). Northam even came to the conclusion in his book Urban Geography that urbanization generally goes through three stages, namely, gradual growth, explosive taking off, and maturity (Northam, 1975). In the first stage, the urban population experiences a gradual growth after it accounts for 10% of the total population. After this proportion being 30%, urbanization process accelerates until urban population reaches 70%, which is called the second stage. This is followed by the third stage, where the urban population stops growing or even starts decreasing. In 2008, urban population in China was 45.7% of the total population (National Bureau of Statistics, 2009). Considering the fact that the correlation between China's urbanization and per capita GDP growth has been the same as that of numerous other countries in history (Feng, 2006), China is in the second stage of urbanization process, which can also be proven by the increasing number of migrants moving from rural areas to urban areas. This demographic change has become the most significant feature in Chinese society. However, urbanization in China has some different characteristics than the western world. In western countries, urbanization is propelled by industrialization, which drives labors, capitals, technologies, land and other means of production to flow into urban areas. In China, on the other hand, urbanization is far beyond the industrialization, which is called "over-urbanization" (Marshall, 1998). This "over-urbanization" is supposed to have come about because rural migrants have been pushed rather than "pulled" into the urban areas (Sovani, 1964). Because of low industrialization level, urban employment capacity cannot satisfy the need of rural migrants; when more and more rural cultivated land is transformed into urban construction land, a new group of "land-lost" farmers have emerged. In rural China where there is hardly any pension system and housing guarantee, "land-lost" farmers have lost their housing guarantee and old-age living …