Temporal-spatial changes and driving forces of built-up land structure in Chengdu City based on information entropy and gray correlative degree analyses

Uses information entropy theory model, this study examined temporal-spatial changes and driving forces of built-up land structure of Chengdu City using land use and concurrent socio-economic data (1996-2010). The results indicated that the information entropy and equilibrium degree of Chengdu had slightly decreased from 1996 to 2010. In contrast, the dominance degree had slightly risen. Furthermore, a downward trend in information entropy was observed in the main city and uptown areas while upward trend was observed in outer suburbs during the study period. In addition, the changes in information entropy in the uptown areas were obvious polarized. Results from the grey correlation analysis demonstrated that the changes of the information entropy were directly cause by the increasing of urban built-up land, transportation land and the reduction of rural residential land, mining land, water conservancy facilities and other built-up land. Furthermore, social and economic development of Chengdu was the root cause of the changes of information entropy. Lastly, there were also close relationships between built-up land structure information entropy and policy planning, geographic conditions and natural disasters.