National-Scale Tidal Flat Elevation Dataset of China Derived from SWOT Altimetry (100 m Resolution)

This dataset presents a national-scale tidal flat elevation product for China’s coastal region derived from Surface Water and Ocean Topography (SWOT) altimetry data at a 100 m spatial resolution. Multi-temporal SWOT observations were aggregated at each grid cell to capture tidal-stage variability across intertidal and supratidal zones.

A tide-constrained percentile-based framework was applied to estimate representative tidal flat elevations from repeated SWOT water surface measurements, reducing the influence of transient noise and unstable extreme values in intermittently flooded areas. The processing workflow integrates SWOT quality filtering, tidal flat masking from the GWL_FCS30 wetland dataset, and coastline refinement using OpenStreetMap data, ensuring spatial consistency at the national scale.

The resulting dataset constitutes the first systematic SWOT-derived tidal flat elevation product covering China’s entire coastal region. Validation against independent elevation references, including airborne LiDAR, GNSS-RTK surveys, and ICESat-2 laser altimetry, demonstrates good agreement and supports its applicability for large-scale coastal analysis.

This dataset provides a consistent topographic baseline for studies of coastal geomorphology, sediment dynamics, sea-level rise impacts, and tidal flat vulnerability assessment.