## 4 Results
### Spatiotemporal Interaction Effects of HF and EQ  
#### 4.2.1 Coupling Coordination Level of HF and EQ  
Given the high complementarity between the HF and EQ patterns in China's lake-ring urban agglomerations, this section employs the CCD model to determine their coupling coordination level. Figure 5a presents the proportion of each CCD category for the five lake-ring urban agglomerations. Overall, the moderate CCD category accounted for the most significant proportion in China's lake-ring urban agglomerations. The Level V and higher proportions remained relatively low but exhibited an increasing yearly trend. For each urban agglomeration, (1) DTU was dominated by CCD categories III and IV, with Level IV maintaining the highest long-term proportion (38.30%), indicating a relatively good level of human-environment coordination. From 2000 to 2020, the overall CCD pattern in DTU remained stable. Level III showed the highest decrease (\(-\)13.12%), while the high-CCD areas of VI and VII levels had a low proportion but grew rapidly. (2) PYU's CCD primarily consisted of Levels II-IV, with Level III exhibiting the highest multi-year average proportion (31.99%). Over time, Levels I-III displayed a decreasing trend, while Levels IV-VII showed annual increases. (3) CHU's CCD category proportions resembled those of DTU, but the proportion of Grade IV was higher (50.45%). From 2000 to 2020, Level III exhibited the most substantial decline (\(-\)46.63%), while the proportions of Levels V-VII rose markedly, indicating an overall improvement in coordination. (4) HZU mainly consisted of CCD Levels IV and V. Level IV exhibited an overall declining trend followed by a rebound, dropping from 50.23% to 25.36% before rebounding to 34.45%. In contrast, Level V became the dominant category after 2010. (5) THU had the highest CCD level among the five urban agglomerations. Between 2000 and 2020, the proportion of levels below IV decreased, while levels above VI expanded significantly, indicating a gradual improvement in human-environment coordination.  
Visualization techniques allowed for a more precise observation of the spatiotemporal evolution process of CCD (Figure 5b). Overall, the multi-year average CCD values of the five lake-ring urban agglomerations from west to east were 0.3740, 0.3371, 0.4485, 0.4930, and 0.5143, respectively, indicating a gradual upward trend over the years. For each category, (1) high-CCD zones (Levels V-VII) formed a belt or ring-like pattern around the built-up areas of each urban agglomeration. The high-value areas continued expanding, especially in the peripheral transportation corridors of CHU, HZU, and THU, which formed distinct connections. (2) CCD buffer zones (Level IV) were primarily located in lakeside croplands and low-altitude plains, forming well-connected transitional layers. Notably, some city centers also exhibited moderate CCD levels due to overdevelopment. With the intensification of urbanization, the buffer zone has borne the burden of industrial relocation and ecological intervention, showing a trend of transitioning into high-value areas. This trend is particularly evident in the buffer zones of CHU, HZU, and THU plain croplands. (3) Low-CCD zones were concentrated in low-density forested regions distant from the lakes, such as the edges of DTU and PYU and the southern parts of CHU, HZU, and THU. These areas retained relatively intact ecological functions, experienced minimal human activity pressure, and consistently maintained low CCD levels. In summary, the overall CCD of China's lake-ring urban agglomerations exhibited a positive development trend. The interaction between policy guidance and land use patterns was pivotal in influencing its spatiotemporal differentiation.