Urban waterlogging resilience assessment and postdisaster recovery monitoring using NPP-VIIRS nighttime light data: A case study of the ‘July 20, 2021’ heavy rainstorm in Zhengzhou City, China

In recent years, with the acceleration of urbanization and abnormal changes in the overall climate, cities have been increasingly threatened and affected by disasters. Assessing and improving urban resilience, as well as postdisaster recovery monitoring, are of great significance for relevant municipal departments. Taking the heavy rainstorm event that occurred on July 20, 2021, in Zhengzhou City as an example, this study explored the resilience and postdisaster recovery of Zhengzhou City based on remote sensing data and other multisource data. First, we calculated the resilience assessment index and built an assessment model. Then, we analyzed and evaluated the resilience. Finally, based on NPP-VIIRS nighttime light data, we verified the accuracy of the resilience results and dynamically monitored the postdisaster recovery process. The results show that the overall resilience of Zhengzhou City to waterlogging disasters is low in the southwest and high in the northeast. The changing trend of the nighttime light brightness following the disaster was consistent with the resilience assessment results. Then, due to rescue work, the light index increased briefly in July; Due to the serious impact of the disaster, the facilities were damaged, and the light index was reduced in August. With the development of recovery work, the disaster-influenced and light index areas gradually recovered and exceeded the predisaster level. Corresponding urban resilience strategies were proposed based on the assessment results. This study can provide a scientific basis and reference for relevant aspects such as disaster prevention, recovery, and reconstruction in Zhengzhou City and other cities.