Evaluation of the Newly Released Worldwide AW3D30 DEM Over Typical Landforms of China Using Two Global DEMs and ICESat/GLAS Data

This paper evaluates the accuracy of newly released global 1 arc-second advance land observing satellite (ALOS) world 3D-30 m (AW3D30) digital elevation model (DEM) over five validation samples of typical landforms across China using ICESat/GLAS (ice, cloud, and land elevation satellite/geoscience laser altimeter system) data. In comparison, shuttle radar topography mission (SRTM) 1-arc second (SRTM1) and global DEM version 2 (GDEM2) are also considered. The result reveals that the RMSEs of mean horizontal shifts compared with SRTM1 and GDEM2 are 5.30 and 10.07 m in x-direction, 5.64 and 11.75 m in y-direction, respectively. The vertical accuracy analysis shows that the AW3D30 offers the highest accuracy with RMSE of 4.81 m, followed by SRTM1 (5.86 m), and then by GDEM2 (14.14 m). Our result reveals that the vertical accuracy can be improved by horizontal alignment. The analysis suggests that terrain slopes and land cover types jointly affect the vertical accuracies of AW3D30 and the former is likely to have a greater impact than the latter. The results of hydrological potential assessment reveal that the drainage network derived from AW3D30 is more accurate than that from SRTM1 and GDEM2. However, all the DEMs exhibit river extraction limitations over the flat area due to the unresolved flow direction based on local elevation information alone. This study provides a comprehensive understanding of the AW3D30 and recommends that applications requiring accurate Earth surface depictions should utilize AW3D30 over SRTM1 and GDEM2, as it presents the best accuracy among the freely available DEMs.