Quantitative Analysis of Spatial-Temporal Differentiation of Rural Settlements Extinction in Mountainous Areas Based on Reclamation Projects: A Case Study of Chongqing, China

Rural settlements in mountainous areas change slowly and are not easy to measure. Reclamation is an important spatial indication of their demise. To measure the spatial-temporal variation of rural settlements extinction from the perspective of regional reclamation projects, and to provide a reference for the scientific evolution of rural settlements in mountainous areas. Based on the data of reclamation projects in Chongqing, China, from 2017 to 2021, with the number of projects, the scale of construction and the scale of newly cultivated land as indicators, coefficient of variation, gravity center model and spatial autocorrelation were used to analyze the distribution characteristics, gravity shift and spatial pattern evolution characteristics of reclamation projects at different spatial scales. The results show that: (1) From the time dimension, the number of reclamation projects, the scale of construction and the scale of newly cultivated land all showed a downward trend, but the differences in the absolute and relative scales of each index gradually decreased, showing a spatiotemporal equilibrium trend. (2) Reclamation projects showed different agglomeration characteristics at different spatial scales. At the regional level, the reclamation projects are concentrated in the city cluster of the Three Gorges reservoir area in Northeast Chongqing. At the district/county level, the reclamation projects are mainly concentrated in Fengjie County (458), followed by Yunyang County (330) and Pengshui County (305), and the least is Wansheng District (32) with an average of about 165. (3) All the centers of gravity in the moving track of the reclamation project center of gravity are located in the city cluster of the Three Gorges reservoir area in northeast Chongqing, and the spatial distribution is geographically balanced. (4) There is a significant agglomeration in the distribution of reclamation projects at the district and county scales. The high-high agglomeration area was mainly concentrated in the city cluster of the Three Gorges reservoir area in northeast Chongqing, and the low-low agglomeration area was mainly distributed in the city proper of Chongqing. The extinction of rural settlements reclamation is affected by regional nature, economy and society, but the land policy is the main driving force. At the same time, we should carefully treat the counties where the rural settlements are disappearing too fast, so as to avoid the drastic changes in the amount and space of cultivated land associated with them.