Mapping Lotus Wetland Distribution with the Phenology Normalized Lotus Index Using SAR Time-Series Imagery and the Phenology-Based Method

Lotus wetland is a type of wetland that can efficiently purify water. Therefore, rapid and accurate remote sensing monitoring of the distribution of lotus wetland has great significance to their conservation and the promotion of a sustainable and healthy development of ecosystems. The phenology-based method has proven effective in mapping some different types of wetlands. However, because of the serious absence of remote sensing data caused by cloud coverage and the differences in the phenological rhythms of lotus wetlands in different areas, achieving high-precision mapping of different regions using a unified approach is a challenge. To address the issue, this article proposes a Phenology Normalized Lotus Index (PNLI) model that combines SAR time-series imagery and the phenology-based method. The results of this study demonstrate that the PNLI model shows good applicability in different areas and has high mapping accuracy. The model can map the lotus wetland distribution in large areas quickly and simultaneously with high precision.