THE SPATIOTEMPORAL EVOLUTION OF LAND USE IN THE NANJING METROPOLITAN AREA AND DELIMITATION OF URBAN DEVELOPMENT BOUNDARIES BASED ON THE PLUS MODEL

Abstract

This study focuses on the spatiotemporal dynamics of land use in the Nanjing Metropolitan Area and the scientific delimitation of its development boundaries. Based on land use observation data from 2000 to 2020, the study found that the Nanjing Metropolitan Area underwent rapid urban expansion over the two-decade period. The built-up area increased significantly from 2,318 square kilometers, reaching nearly double the 2000 level by 2020, while farmland—the land use type that shrank the most—decreased by a total of 4,171 square kilometers. By incorporating the PLUS model, this study identified the drivers of land expansion and conducted multi-scenario projections of land use patterns for 2025 and 2030. The results indicate that under natural evolutionary trends, construction land will continue to encroach upon farmland and ecological spaces. To curb the disorderly sprawl of urban areas, the study established a delineation approach centered on “ecological priority, farmland protection, and coordinated development.” Using GIS spatial analysis techniques and incorporating the rigid constraints of ecological and farmland red lines, the study preliminarily delineated the rigid urban development boundary for the Nanjing Metropolitan Area. The delineation results indicate that the total area of the rigid development boundary within the study area is 93,474.54 hectares, accounting for 65.45% of the total land area, primarily encompassing basic farmland protection zones and ecologically sensitive areas. The framework established in this study provides quantitative evidence and spatial constraint schemes for the optimization of territorial space and sustainable development at the metropolitan level.