Evolution and Drivers of Wetland Types in China's Coastal Wetlands (1990-2020)

China's coastal wetlands are ecologically rich but lack long-term, high-resolution maps, impeding research on wetland change drivers. To address this, we developed a 1990-2020 wetland dataset using Google Earth Engine (GEE) and geospatial artificial intelligence (GeoAI), based on Landsat imagery (30 -meter resolution), to analyze spatiotemporal dynamics and driving forces across 12 coastal provinces (Liaoning, Hebei, Tianjin, Shandong, Jiangsu, Shanghai, Zhejiang, Fujian, Guangdong, Guangxi, Taiwan, Hainan). Results show a total wetland area decline of approximately 8.67 %, from 61,932 km<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> to 56,543 km<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>. High-value wetlands (e.g., rivers, lakes, tidal flats) decreased by 22.45 %, while medium-value wetlands (e.g., agricultural ponds, coastal breeding ponds) increased by 46.27 %. Non-wetland areas (e.g., forests, built-up land) were slightly reduced by 1.03 %, though impervious surfaces surged by 150.28 %. Wetland changes followed three main patterns: stability, primarily in ecologically protected areas (e.g., Fujian, Hainan); degradation, driven by urbanization, industrialization, and agriculture (e.g., Jiangsu, Zhejiang); and limited recovery, such as through mangrove planting. Key direct drivers include urbanization converting wetlands to built-up areas, agricultural expansion encroaching on high-value wetlands, and climate change (e.g., sea-level rise) affecting stability. Indirect drivers encompass policy interventions (e.g., wetland protection laws) promoting stability and recovery, economic growth intensifying degradation, and technological advances enhancing monitoring capabilities. These findings highlight pressing challenges for coastal wetland conservation, emphasizing the need for integrated policies that balance ecological protection and economic development. By aligning with global biodiversity and sustainability frameworks, this study provides actionable evidence to guide national and regional policy-making and advance the achievement of SDG targets.