Dynamics in construction land patterns and its impact on water-related ecosystem services in Chengdu-Chongqing urban agglomeration, China: A multi-scale study

Water-related ecosystem services (WES) are paramount for the development of sustainable urban agglomerations. The impact of construction land pattern (CLP) changes on WES varies by spatial scale; however, a comprehensive multi-scale analysis of CLPs and their impact on WES in urban agglomerations is still lacking. Focusing on the Chengdu-Chongqing urban agglomeration (CCUA) within the Yangtze River Economic Belt, China, this study investigated the CLPs using multidimensional measures (intensity, complexity, and aggregation) at various scales: watershed, county, township, and grid. Using geographically weighted regression (GWR), the multi-scale impacts of the multidimensional CLP on WES (including water yield, soil retention, water purification, and habitat quality) were assessed and the scale effects and spatial heterogeneity were explored. The key findings include the following: (1) Significant changes in the CLPs within the main stream of the Qingyi and Minjiang watersheds have been observed over the past two decades. (2) The CCUA forms a network of construction land connecting all cities, with Chengdu and Chongqing as the main nodes. (3) Construction land complexity demonstrates a concentric distribution, with increasing complexity from the center outward and simplification toward unurbanized areas. (4) Substantial local and regional impacts of the CLPs on WES were found across multiple scales within the CCUA. (5) Increasing the complexity and aggregation of construction land facilitates the protection of WES in rapidly urbanizing areas (e.g., megacities), whereas the opposite is true in small cities and remote mountainous areas. This research enhances our understanding of construction land dynamics and their implications for WES, contributing vital insights into water-related ecological safeguarding and fostering sustainable regional development in urban agglomerations.