Monitoring the Different Types of Urban Construction Land Expansion (UCLE) in China's Port City: A Case Study of Ningbo's Central City

The internal structure of urban construction land expansion (UCLE) is closely related to urban sustainability, and the UCLE in China's port city has a unique pattern. This study attempted to monitor the internal structure evolution of UCLE based on construction land transfer data in Ningbo's central city from 2002 to 2015. Equality fan analysis and kernel density analysis were applied to characterize the spatial-temporal dynamics of different types of UCLE and to summarize their evolution patterns. The results revealed that in the whole study area, the rank of the expansion size and intensity of construction land was: industrial land > traffic land > residential land > public land > commercial land. The dominant directions of all types of UCLE were the directions of the port zones. In the port zones, there were more apparent expansion trends and higher expansion intensities of industrial, traffic and public lands, which meant that the port had significant impact on UCLE, especially in terms of industrial land. Additionally, commercial and residential land expansions showed a circle-shaped gradient pattern; industrial land sprawl was in a leapfrog pattern; public and traffic land sprawl was illustrated in a bi-centric pattern. In the future, local government should encourage the development of residential and public land rather than industrial land, and shift the present industry structure which dominated by industry to a more balanced structure, in order to achieve sustainable development.