Sustainable evaluation of the eco-economic systems in the π-shaped Curve Area of the Yellow River basin of China: a study based on the 3D ecological footprint model.

Sustainable evaluation of the eco-economic systems is crucial to resolve the contradiction between environmental protection and economic development and promote healthy urban development. This paper constructed an SEC framework for sustainable development index (SDI) evaluation of the eco-economic systems in the π-shaped Curve Area in the Yellow River basin based on the 3D ecological footprint (EF) model. The study was conducted from three aspects: the capital utilization scale and equity during the ecological supply and demand process, the development efficiency and capacity of the eco-economic systems, and the relations between the systems embodied by the coordination and security evaluation. Also, the SDI and its influence mechanism were studied using the fully arrayed polygon diagram and geographic detector. Findings include the following: EF depth is higher in cities with poor natural resources, while EF size is higher in cities with vast territories and rich resources. The arrangement of EF depth and EF size presents nearly a reverse trend, and the consumption of capital flow and capital stock complements each other. Cities can be classified as heavy utilization type, moderate utilization type, mild utilization type, and low stock appropriation type. From 2005 to 2019, the area's SDI and the three aspects presented evident spatial heterogeneity and formed clusters. The role of government, energy consumption, scientific innovation, industrial structure, urbanization rate, population, economic level, and openness level impact SDI differently. This study proposed a new insight for the sustainability evaluation of eco-economic systems.