Characterizing Long-Term Urban Impervious Surface Dynamics and Landscape Pattern Evolution Through an Integrated Area–Density Perspective

Impervious surface expansion is a defining manifestation of urbanization, but changes in total area alone cannot reveal how transitions in development density reshape landscape structure. Adopting an integrated area–density perspective, this study examined impervious surface expansion and landscape reconfiguration in Zhengzhou, China, using Landsat observations from 1990, 2000, 2010, and 2019. Impervious surface fractions were estimated using dynamic endmember linear spectral mixture analysis. Impervious surface area (ISA) was assessed using expansion statistics, spatial autocorrelation, and standard deviational ellipses, while transitions among six impervious surface percentage (ISP) classes were analyzed using transition matrices and landscape metrics. Total ISA increased from 71.12 to 523.34 km2. Absolute expansion peaked during 2000–2010, whereas annual expansion intensity declined from 14.70% in 1990–2000 to 4.07% in 2010–2019. ISA expansion exhibited significant positive spatial autocorrelation (Moran’s I = 0.404–0.663), and the footprint retained a southeast–northwest orientation. Natural surfaces declined from 92.16% to 12.75%, accompanied by growth in high-density and fully impervious classes. Decreasing CONTAG and increasing SHDI indicated weakened landscape continuity and greater configurational diversity. Urban development shifted from outward land conversion toward heterogeneous density reconfiguration. Sustainable planning should prioritize reconnecting residual natural surfaces, managing growth in fragmented transition zones, and promoting redevelopment in high-density areas.