What drives urban growth in China? A multi-scale comparative analysis

Driving forces of urban growth differ across spatial scales, but most previous studies have been done for single cities of different sizes. Multi-scale analysis of urbanization drivers is still lacking. In this study, we investigated the drivers of urban growth in the central Yangtze River Delta, China from 1990 to 2008, using a hierarchical patch dynamics (HPD) approach that consisted of three spatial scales or hierarchical administrative levels of county, prefecture, and the region. Logistic regression, partial least square regression, and Pearson correlations were used to identify specific drivers. Our results show that the main drivers of urban growth differed between hierarchical levels and over time. First, urban growth occurred frequently next to existing urban land for most cities at all the hierarchical levels, while accessibility to railways, waters and prefectural cities became unimportant to urban expansion over time. Second, GDP, non-agricultural population proportion, gross industrial output and foreign investment in actual use were the top four important socioeconomic factors influencing urban growth for the majority of cities at both the prefectural and county levels, but the relative importance of the key influencing factors of urban growth differed across different hierarchical levels. Third, economic policies and institutional shifts by the central and local governments also played an important role in urban growth especially for cities of Wuxi and Changzhou. These multiscale relations of urban growth to potential drivers, revealed via the HPD approach, are useful for strategic planning to curb excessive urban expansion in the study region. Although the geographical and socioeconomic variables could independently explain more than 75% of variations of urban growth across spatial and temporal scales, the impacts of their interactions on urban growth need further studies in the future.