Detection of Wetland Degradation and Restoration in Urbanizing Zhuhai City based on Google Earth Engine

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Wetlands play a crucial role in maintaining ecological balance and promoting sustainable social development. Accurately detecting the spatio-temporal changes of wetlands is essential for coastal ecological conservation and management. Taking Zhuhai City as a case study, we employed a methodology combining random forest classification and recursive feature elimination to classify long-term scale wetlands using the Google Earth Engine cloud platform. Landscape pattern indices were introduced to detect the spatial and temporal evolution of wetlands over the past 35 years. The degradation and restoration of wetlands between 2013 and 2022 were evaluated by examining landscape changes. The results indicate that incorporating seasonal variation features can effectively distinguish between mangroves and paddy fields. Feature selection has significantly improved the classification accuracy. From 1988 to 2022, the area of wetlands in Zhuhai City decreased by 11.88%, with natural wetlands continuously declining. Human activities have escalated fragmentation, decreased homogeneity, and reduced interconnectivity of wetland landscapes. Between 2013 and 2022, the total area of degraded wetlands exceeded that of recovered wetlands. Although the extent of functional wetlands with high degradation rates has decreased since 2018, the area of recovered wetlands has also declined. Urbanization and natural environmental change factors are conducive to the wetland degradation. This study proposes a generic approach for monitoring wetland dynamics, providing data support and a scientific basis for wetland conservation and risk management in coastal regions. In the future, it is advisable to implement multi-departmental coordination mechanism in the management of wetland resource, strictly restrain the activities of reclamation and aquaculture, establish protection red lines, maintain existing protection areas, and enhance public awareness on wetland conservation. These measures aim to balance economic growth with wetland conservation, ensuring the long-term health of Zhuhai's vital wetland ecosystems.