ABSTRACT

Topographic data is increasingly available from LiDAR (Light Detection and Ranging) surveys. This research evaluates the limitations and capabilities of a LiDAR Digital Terrain Model (DTM) regarding catchment topography representation and river drainage network derivation, considering high-resolution (1 m) and resampled versions (2, 5, 10, and 30 m), and the Garças river basin (4,100 km²; Pernambuco state) as a study case. The terrain representation of the 1m-DTM and the derived network present outstanding quality, and its coarsening up to 30m resolution still outperforms the results obtained with SRTM data. LiDAR DTM coarsened to 2, 5, 10 and 30 m led to river length shortening of 0.1%, 0.3%, 1.2%, and 4%, respectively, while the difference between LiDAR 1m and SRTM was about 12%. The computational cost for 1m-DTM processing was prohibitive when using a typical low-cost computer, while some algorithms proved to be largely efficient (100 times faster) when running on a more powerful machine. DTM coarsening is an alternative to achieving a better balance between data quality and computer requirements.

Keywords:
Digital terrain model; Resampling; Flow directions; Digital elevation model; Computational cost