A remote sensing-based approach for spatiotemporal refined assessment of freshwater wetland ecological risk in coastal zones: A case in Jiangsu's coastal zone

Rapid, long-term, and robust wetland ecological risk assessment is critical for managing coastal zones. In view of the characteristics of frequent human activities and broken plots in the coastal zone, the traditional assessment method is not fine enough. Satellite earth observation provides an unparalleled source of data for rapidly monitoring and assessing coastal wetland ecological risks through time and across a large spatial range. With the support of multi-source remote sensing data such as precipitation, temperature, night light, land cover products, etc., a wetland ecological risk assessment method is established in this paper, and the wetland ecological risk is evaluated year by year by a grid. The evaluation results indicate that the ecological risk level of coastal wetlands in Jiangsu Province has shown an upward trend since 2015, with a high ecological risk in the north and a low ecological risk in the south, and the source area mainly appears in the northwest. Meanwhile, the year-by-year grid assessment can not only accurately describe the spatial and temporal distribution of wetland ecological risks but also clarify the spatial and temporal characteristics of risk source areas. Additionally, the results obtained by year-on-year assessment of consecutive years and clustering and zoning according to the time-series can better represent the risk status of the time period and exclude the impact of accidental factors on the evaluation results. Although optimization for different types of wetlands can improve the accuracy of assessment, more wetland risk assessment with a longer term and a larger scale, combined with carbon emissions, will provide a basis for global wetland management.