This paper explored the impacts of the changing urban form on the ecological efficiency of administrative areas and urban agglomerations in China under different regional scales using the slack-based measure of efficiency model. It also measured the morphological characteristics of cities across several regions using the Largest Patch Index (LPI), Patch Density (PD), and Fractal Dimension (FD). Using the threshold regression model, the impact mechanism of urban form on ecological efficiency was examined. Results show that the ecological efficiency of the regions show an “N” type change over time. LPI and PD show a significant impact in promoting ecological efficiency while FD inhibits ecological efficiency but is not significant until the regional scale reaches 1,352 km². We conclude that the development of urban agglomeration is more conducive to improving regional ecological efficiency, which will give policymakers some inspiration in developing a regional development strategy.

In order to explore the differential impacts of various types of surface water bodies on urban expansion, Taking the data in 2000, 2010, and 2020 of Tianjin as research subjects, this paper establishes the Autologistic regression models to investigate the influence of factors such as proximity to different types of surface water bodies, presence within flood storage and detention areas, and their association with aquatic ecological corridors on urban expansion. The results show that 1) flood storage and detention areas are significant constraining factors for urban expansion and the primary rivers are a more pronounced driving effect compared to other surface water bodies; 2) over the period from 2000 to 2020, the driving effect of surface water bodies on urban expansion exhibits a declining trend; 3) The delineation of urban construction land boundaries and the establishment of ecological protection zones are identified as the principal external factors shaping urban expansion. The results further explained the relationship between cities and water, and can provide a theoretical basis for the harmonious coexistence of cities and water environment.