Construction of Digital Elevation Models on the Intertidal Flats Using TanDEM-X Bistatic Observations 

Coastal environments, including intertidal flats, are ecologically important systems that might be threatened by rising

sea levels or anthropogenic activities. Topographic information is a useful resource for managing coastal regions. This letter suggests a suitable method for constructing high-accuracy digital elevation models (DEMs) using bistatic observations during the TanDEM-X (TDX) Science phase. Almost zero temporal and large geometric (1.5?2 km) baseline configuration is optimal for deriving intertidal flats’ low topographic relief. The results effectively capture the low-lying elevation in intertidal flats. 

Validation with the Ice, Cloud, and Land Elevation Satellite2 (ICESat-2) altimetry measurements shows good agreement (R2 : 0.65?0.85). 

The smallest height of ambiguity (HoA) yields the minimum root mean square error (RMSE) of 0.22 m with the highest correlation. However, a large perpendicular baseline degrades interferometric correlation, even in agricultural or bare land, owing to volume decorrelation. Our findings suggest that frequent TDX bistatic observations will be helpful in better understanding the coastal environments. 

Index Terms― Digital elevation model (DEM), height of ambiguity (HoA), synthetic aperture radar interferometry (InSAR), intertidal flats, TanDEM-X (TDX).