## 4 Results  
### Spatiotemporal Evolution Patterns of HF and EQ  
4.1.1. Spatiotemporal Evolution Characteristics of HF  
Figure 3a shows the numerical development trend of HF in China's lake-ring urban agglomerations from 2000 to 2020. Overall, HF values in the lake-ring urban agglomerations exhibited a marked increase over the 20 years. The proportion of low-value areas (Levels I and II) decreased progressively from 74.64% to 62.41%. The buffer zone (Level III) remained stable, fluctuating between 11.70% and 12.58%. The proportion of high-value areas (Levels IV and V) rose from 12.79% to 25.89%, with Level V exhibiting the highest growth rate of 169.11%. For each urban agglomeration, (1) in DTU and PYU, low-value areas predominated, with multi-year average proportions of 87.71% and 90.17%, respectively. Although the high-value areas remained low in proportion, they experienced rapid growth, increasing by 236.20% and 315.71%, respectively. This trend suggests an increasing risk of potential human-environment conflict. (2) CHU and HZU showed significant growth in the buffer zone proportion. The proportion of low-value areas in CHU declined markedly compared to DTU and PYU, approaching the regional average (63.25%). HZU had the highest proportion of buffer zones (30.08%), indicating a marked tension between urban expansion and ecological protection. (3) THU represented the only urban agglomeration where high-value areas form the absolute majority, demonstrating a continuous expansion trend. The Level V increased from 29.19% to 64.03%. This urban agglomeration contributed 119.38% to the increase in V-level areas, making it a critical zone for controlling the further intensification of HF in China's lake-ring urban agglomerations.  
Based on the numerical analysis results, this section further examines the spatiotemporal evolution characteristics of the HF pattern in lake-ring urban agglomerations (Figure 3b). Overall, the mean HF values from west to east across the urban agglomerations were 0.0525, 0.0452, 0.1052, 0.0928, and 0.2509, respectively, forming a distribution pattern of \"higher in the east and lower in the west.\". The HF distribution within the study area demonstrates three distinct spatial patterns among five lake-ring urban agglomerations: (1) DTU and PYU displayed an HF distribution featuring a distinct point-like radial structure, dominated by low-value forested areas at high inland altitudes, with high-value urban centers near the lakeshore interspersed as radiating nodes. This spatial pattern has become increasingly polarized over time. (2) The spatiotemporal distribution pattern of CHU and HZU exhibited a multi-level clustering structure, with dominant central cities as the primary core and prefectural government seat locations as secondary nodes. In CHU, the dominant city was Hefei, the provincial capital located on the western shore of Chaohu Lake, while in HZU, it was Huai'an, a transportation hub city situated north of Hongze Lake. The spatial uniformity of HF became more evident over time. (3) THU displayed an HF distribution featuring a ring-shaped spatial pattern, with clusters of high-value areas around TaihuLake extending toward the built-up coastal urban areas in the east. In summary, the HF values of the lake-ring urban agglomerations indicate an increasing intensity of human intervention. The spatial development demonstrates a strong hydrophilic tendency, primarily characterized by outward growth from the lake center along river corridors.