Fusion of Copernicus and ALOS World 3D DEMs for Watershed and Stream Network Delineation

EasyChair Preprint 7994

Abstract

The terrain representation and hydrological correctness of DEMs can be improved through fusion, but very few researchers have demonstrated this. In this study, we compare watersheds and drainage networks delineated from Copernicus GLO-30 and AW3D DEMs, a fused version of both DEMs, and a 10m aerial LIDAR DEM. The DEMs were co-registered, and the LIDAR DEM was resampled to 30m. The fusion of Copernicus and AW3D was achieved through weighted averaging. The watersheds and stream networks were generated across different terrain contexts in the Table mountain, Cape Town Peninsula and cultivated fields in the Western Cape Province of South Africa. Basic watershed properties such as stream length and watershed area were calculated and compared. The terrain visualisation shows that the fused DEMs are more consistent with the LIDAR DEM. The narrow drainage stems in the Diep River floodplain are not precisely depicted by Copernicus and AW3D due to their coarse resolution. In the Cape Peninsula, the hydraulic lengths of the streams from the fused DEM are closest to the LIDAR DEM, whereas in the cultivated fields, the streams delineated from Copernicus are closer to the LIDAR DEM, followed by the fused DEM. In the cultivated fields and Cape Peninsula, Copernicus and AW3D overestimate the actual stream lengths, whereas in the Table mountain, both DEMs underestimate the lengths. There are no differences in the watershed areas from all DEMs in the cultivated field, and the stream lengths from the fused DEM are more closely aligned with the LIDAR DEM. Summarily, through the fusion of Copernicus and AW3D, the hydrological characterisation was improved.

Keyphrases: ALOS World 3D, Copernicus GLO-30, DEM fusion, Digital Elevation Model, stream networks, topographic mapping, watersheds

@booklet{EasyChair:7994,
  author    = {Chukwuma Okolie and Jon Mills and Julian Smit},
  title     = {Fusion of Copernicus and ALOS World 3D DEMs for Watershed and Stream Network Delineation},
  howpublished = {EasyChair Preprint 7994},
  year      = {EasyChair, 2022}}