Coupled ecological pressures in urban environments: regional heterogeneity and drivers of carbon and water footprints

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A synergistic assessment of carbon and water footprints is essential for capturing the complexity of compound ecological pressures in rapidly urbanizing cities. However, their spatial distributions and integrated mechanisms at the district scale remain insufficiently explored and quantified. This study develops a spatially explicit analytical framework that integrates carbon and three types of water footprints (on-site blue water, runoff blue water, and road runoff gray water) with spatial autocorrelation and the Optimal Parameters-based Geographical Detector (OPGD) method. The analysis focuses on six central districts in Guangzhou, China, and evaluates spatial clustering patterns alongside the joint effects of natural and human drivers. The results reveal significant intra-urban clustering and a distinct core–periphery gradient in ecological footprints. This pattern is shaped primarily by urbanization intensity, human activities, and natural features, and interactions among these drivers generate marked nonlinear amplification. Consequently, ecological burdens are concentrated in densely populated and intensively developed districts, exacerbating spatial inequality and exposing specific areas to elevated environmental risks. The convergence of high urbanization levels with overlapping ecological pressures underscores the urgency of targeted urban sustainability strategies. The study proposed a district-scale multi-footprint framework that identifies nonlinear synergistic drivers and demonstrates its applicability for ecological risk identification in rapidly urbanizing regions. Moreover, these findings provide practical implications for the strategic deployment of green infrastructure and nature-based solutions, with potential relevance for other metropolitan regions experiencing similar developmental pressures.