Coupling and coordination evaluation of digital economy and green development efficiency in eight urban agglomerations in China

Promoting the coupling and coordinated development of the digital economy and green development efficiency within urban agglomerations is of vital importance for the construction of "Digital China" and "Beautiful China", and is also significant for achieving regional sustainable development. This paper uses the relevant data of 140 cities in the eight urban agglomerations in China from 2011 to 2023 to comprehensively measure the development levels and coordination degrees of the digital economy and green development efficiency from the perspective of urban agglomerations. Furthermore, by applying multi-index evaluation methods, the EBM-DEA model based on Pearson correlation coefficient, and the coupling coordination degree model, the systematic evaluation and relationship analysis of the digital economy and green development efficiency were carried out. The research results are as follows: (1) The overall coupling coordination degree of two systems in the eight major urban agglomerations in China shows a fluctuating growth trend, achieving a transformation from near imbalance to good coordination, but there are obvious phased characteristics and regional imbalances. (2) In the eight urban agglomerations, the overall Gini coefficient of the coupling coordination degree of these two systems shows a fluctuating downward trend, presenting a "rising-falling" inverted "V" shape feature, and the spatial differences gradually narrow. (3) The stability of the coupling coordination degree at all levels in the eight urban agglomerations is relatively high, with obvious solidification phenomena. The improvement process is gradual, and there is a certain risk of grade decline. These conclusions provide scientific basis for urban agglomerations to formulate precise policies, balance economic and ecological development, and achieve high-quality development.