Assessing the Effect of Urban Growth on Surface Ecological Status Using Multi-Temporal Satellite Imagery: A Multi-City Analysis

Quantification of Surface Ecological Status (SES) changes is of great importance for understanding human exposure and adaptability to the environment. This study aims to assess the effect of urban growth on spatial and temporal changes of SES over a set of neighboring Iranian cities, Amol, Babol, Qaemshahr, and Sari, which are located in moderate and humid climate conditions. Firstly, the built-up footprint was prepared using Landsat images based on the Automatic Built-up Extraction Index (ABEI). Then, the surface biophysical characteristics were calculated. Secondly, the SES was modeled using the Remotely Sensed Ecological Index (RSEI), and the spatio-temporal changes of the SES were evaluated. The results revealed that the average RSEI for these cities increased from 0.48, 0.51, 0.53, and 0.55 in 1986 to 0.69, 0.77, 0.75, and 0.78 in 2022, respectively. The proportion of the poor ecological condition class in these cities rose from 10%, 3%, 5%, and 1% to 74%, 64%, 54%, and 41% during the 1986-2022 period. Our findings indicate that the SES of these cities significantly decreased while they experienced large physical growth. The findings and the methodical approach of the study provide a data-driven approach for monitoring SES in fast growing regions, which is required for studying the impact of climate change on society.