[Spatial-temporal differentiation and influencing mechanism of green development efficiency in three major urban agglomerations in Zhejiang Province, China.]

Improving the green development efficiency of the three major urban agglomerations in Zhejiang is an important way to faster build the pilot demonstration area of beautiful China. Based on county panel data from 2000 to 2019 of 41 counties (cities) included in the three major urban agglomerations, we combined the super-efficiency SBM model with window analysis to evaluate the efficiency, and used spatial econometric analysis method to study the spatial distribution and the differences in regional difference. Furthermore, the fixed panel fixed effect model was used to explore the differential influencing mechanism. The results showed that green development efficiency of the three major urban agglomerations increased gradually with fluctuations during the study period. The distribution of efficiency values gradually shifted from a situation of 'high in the north and low in the south' to a 'relatively common and coordinated' development in the various regions. There was a significant spatial agglomeration effect in green development efficiency of the three major urban agglomerations, but it presented fluctuating phenomenon among cities which were at the similar level. The average green development efficiency of central Zhejiang urban agglomeration was the highest. The development within the three major urban agglomerations was relatively stable. The annulus Hangzhou Bay urban agglomeration came next, with stable development. The Wenzhou-Taizhou coastal urban agglomeration was the lowest, but the efficiency enhancement was the largest. The increases in population density, along with the proportion of added value of tertiary industry in GDP, per capita industrial added value, local fiscal expenditures, education expenditures and per capita actual use of foreign capital could improve the efficiency of green development. However, the increases in industrial electricity consumption and fixed asset investment in kennels would inhibit the improvement of green development efficiency. The impacts of per capita industrial added value, local fiscal expenditure, education expenditure and per capita actual use of foreign capital on urban agglomerations were heterogeneous among different cities.