Mapping Urban Impervious Surface and Measuring Its Spatio-temporal Dynamics in Zhengzhou, China

Information on urban dynamics is crucial for tracking expansion and investigating urbanization-related environmental impacts. Accurate and timely monitoring of long-term urbanization trends, however, presents significant challenges. Leveraging impervious surface area as a primary metric, this research analyzes spatio-temporal urbanization dynamics and landscape pattern responses in the Zhengzhou metropolitan region between 1990 and 2019, using a novel dual-analytical approach. The total ISA of Zhengzhou increased from 71.12 km ² in 1990 to 523.34 km ² in 2019, with an annual growth area of 15.59 km ² . There was significant positive spatial autocorrelation in the expansion speed of ISA between different regions, and the hot spots with rapid development varied from period to period, namely Erqi, Zhongyuan, and Huiji districts from 1990 to 2000, Huiji, Jinshui, and Guangchegn districts from 2000 to 2010, and Zhongyuan, Huiji, and Guancheng districts from 2010 to 2019. Overall, the impervious surface expansion presented a pattern dominated by the direction of "southeast to northwest". The ISP of each level increased or decreased to varying degrees during the study period, and the change of ISP levels indicated significant change of the pattern of urban landscape, and the overall landscape shape showed a trend from simple to complex. The depiction of the urban impervious surface development trajectory could provide a meaningful resource for urban managers and policy makers implement the national central city construction strategy in Zhengzhou metropolis.