Spatial-Temporal Dynamics and Driving Mechanisms of Urban Construction Land in Mega Cross-River Mountain Cities: A Case Study of Chongqing's Central Urban Area, China
Authors: 王 福海 , CHEN Dan , LI Hui 
Published: October 2023

Abstract
The dynamics of urban construction land in terms of scale and structural changes constitute the foundational pillars of research in territorial spatial development and planning. However, prior investigations have predominantly fixated on the patterns and models of horizontal expansion within urban construction land, paying comparatively scant attention to the regulatory patterns and impacts concerning the three-dimensional gradient of construction land "ascension.". Therefore, this study, based on high-precision land change survey data, elevation data, and administrative district data from 2010 to 2020, employs methodologies including construction land slope analysis, intensity analysis framework, LISA temporal pathways, spatiotemporal transitions, and the PLUS model. From the perspectives of both two-dimensional and three-dimensional expansion of construction land, the research delves deeply into the intensive analysis of the spatial growth process and driving factors of construction land in the central urban area of Chongqing, which experienced the most drastic expansion in urban construction land in China. The research findings indicate the following: (1) From the perspective of vertical expansion of construction land, in the central urban area of Chongqing, from 2010 to 2012, there was a gradual expansion of construction land into lower-slope areas, whereas from 2012 to 2020, it gradually extended into higher-slope regions. Furthermore, the intensity of construction land ascent significantly heightened after 2012, reaching its pinnacle between 2014 and 2016.(2) During the period from 2010 to 2020, there was a systematic inclination towards the transformation of arable land into construction land. Conversely, grassland to construction land, forestland to construction land, water bodies to construction land, and other land types to construction land exhibited tendencies of both absolute and relative shifts away from construction land. Additionally, there was a systematic tendency observed in the conversion from construction land to arable land. In contrast, the transformation from construction land to grassland, forestland, water bodies, and other land types exhibited a systematic inhibitory pattern.(3) Since 2010, there has been a steady increase in construction land expansion intensity in the central urban area of Chongqing. This progression has evolved from slow and balanced growth to rapid and uneven growth, leading to a gradual expansion of spatial disparities. The intensity changes in expansion across various townships exhibit spatial alternation. High-intensity areas are gradually converging towards the eastern part of Jiangbei District, the southern part of Yubei District, and Shapingba District, while low-intensity areas are concentrated in Beibei District and Baxian District.(4)In the central urban area of Chongqing, the majority of regions remain in a relatively stable spatial state, without undergoing noticeable leaps or transitions. This highlights a spatial locking characteristic in the intensity of construction land expansion.(5) The expansion of construction land in the central urban area of Chongqing is significantly influenced by factors such as topography, rivers, tunnels, and rail transportation, among others. The research findings can serve as a scientific foundation and decision-making reference for the rational planning of similar mountainous cities spanning riverbanks.