Integrating ICESat-2 altimetry and multi-source satellite imagery to track annual changes of Jiangsu central tidal flat topography over 2009–2024

• A novel satellite-driven framework for high-resolution, long-term tidal flat DEMs. • A 16-year annual topographic dataset of the tidal flats in Central Jiangsu. • A cost-effective and powerful tool for global coastal tidal flat applications. Tidal flats, as highly dynamic transitional zones between land and sea, are crucial for ecological balance and socio-economic development. Mapping their annual topographic dynamics is essential for coastal sustainability and tidal flat utilization. However, accurately tracking topographic evolution of tidal flats remains challenging due to the lack of up-to-date, high-frequency Digital Elevation Model (DEM). This study developed a novel satellite-driven framework to generate annual, 30-m resolution DEMs spanning 2009–2024 for Jiangsu central tidal flat-the largest and most dynamic tidal flat system in China, characterized by highly complex hydrodynamics. Specifically, we achieved this by integrating Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) altimetry with 1,047 scenes of multi-source optical imagery (Landsat-5/7/8/9, Sentinel-2, GF-1, HJ-1A/B, and HJ-2A/B). Our DEMs, validated against airborne lidar data, achieved a mean root mean square error (RMSE) of 0.34 m in 2024 and a RMSE of 0.37 m in 2019. Critically, our method increased mapped tidal flat area by 14.36% and improved elevation accuracy by 38.32% compared to the conventional single-sensor approach. Moreover, our generated DEMs outperformed three existing regional datasets in temporal coverage and eight global DEM products in both accuracy and spatial coverage. The analysis revealed that Jiangsu central tidal flat experienced a net area loss of 116.62 ± 12.28 km 2 over the past 16 years. Elevations showed a decreasing trend at a rate of −0.02 ± 0.01 m year −1 , with 79.94% ranging from −0.7 to 2.1 m. 95.06% of elevation changes occurred within the −1.0 to 1.0 m range, with a net volume increase of 9.39 ± 0.06 × 10 7 m 3 . Tiaozini and adjacent Gaoni areas experienced pronounced erosion and deposition during the 2014–2020 period. This proposed satellite-based framework eliminates the need for in-situ measurements, providing a robust and cost-effective tool for generating long-term tidal flat topography. The resulting high-resolution DEM time-series offers critical data for hydrodynamic modeling and sustainable coastal development, demonstrating large potential for global-scale applications.