Abstract: Based on the road network data of 1990, 1994, 2000, 2005 and 2009 and urban integrated power index measured by factor analysis in the Pearl River Delta, this paper estimates county potential index using expanded potential model, and explores the spatio-temporal association structure and evolution of county potential using spatio-temporal autocorrelation techniques, and the validity of spatio-temporal association structure is verified in comparison of spatial association pattern and cross correlation function. The main results are obtained as follows: (1) The global spatio-temporal association of county potential showed a positive effect. But this positive effect was not strong, and it increased slowly from 1994 to 2005 and presented a decreasing trend from 2005 to 2009. The local spatio-temporal association characteristics of most counties' potential kept relatively stable and focused on a positive autocorrelation, however, there were obvious transformations in some counties among four types of local spatio-temporal association which are HH, LL, HL and LH. (2) The distribution difference and its change of local spatio-temporal association types of county potential were obvious. Spatio-temporal HH type units were located in the central zone and Shenzhen-Dongguan region of the eastern zone, but the coverage of the spatio-temporal HH area of the central zone shrunk to the Guangzhou-Foshan core metropolitan region only after 2000; the spatio-temporal LL area in the western zone kept relatively stable with a surface-shaped continuous distribution pattern, new LL type units began to emerge in the central and southern zones in 2005, the LL area in the eastern zone expanded from 1994 to 2000, and then gradually shrunk and scattered at the eastern edge in 2009; the spatiotemporal heterogeneity (HL and LH) area changed significantly. (3) The diversity of local spatiotemporal association of county potential among the three zones showed significant imbalance. The difference between the eastern and central zones tended to decrease, whereas that between the western zone and the central and eastern zones further expanded. (4) Spatio-temporal autocorrelation methods can efficiently mine the spatio-temporal association patterns of county potential, and can better reveal the complicated spatio-temporal interaction between counties than ESDA methods.

Key words: urban potential, spatiotemporal autocorrelation, spatio-temporal association structure, spatio-temporal Moran’s I, Pearl River Delta