3.4. Coordination degree index of water pollution emissions
intensity and per capita GDP
In this section, we discussed the coordination degree index as
shown in Fig. 7. The coordination degree index captured the difference
in coupling degree for regions in the stage analysis. Using Fig. 7
(a) as an example, the coordination of industrial water pollution
emissions intensity and per capita GDP in Hainan is better than that
in Hebei. Shandong and Guangdong have the highest coordination
degree of industrial water pollution emissions intensity and per
capita GDP in the transitional stage. Beijing has the highest coordination
degree of industrial water pollution emissions intensity and
per capita GDP in the “less polluted, more developed” stage. We can
conclude that our coordination degree index is a reliable indicator
to compare the sustainability performance among different regions
in the same level of development stage.